Getting to Grips with Aircraft Weight and Balance 1SYSTEMS A. Cargo Systems .......................................................................... 9 1. Type of ULDs and Configuration........................................................................................... 9 1.1. History............................................................................................................................ 9 1.2. IATA identification code for Unit Load Devices (ULDs)................................................. 10 1.3. ULDs among the AIRBUS fleet .................................................................................... 14 2. Cargo Holds descriptions.................................................................................................... 19 2.1. Bulk cargo system........................................................................................................ 19 2.2. Cargo Loading Systems (CLS):.................................................................................... 21 2.3. Cargo loading system failure cases.............................................................................. 28 2.4. Additional Cargo holds related systems ....................................................................... 29 B. Fuel Systems ........................................................................... 38 1. Generalities ........................................................................................................................ 38 2. The Single-Aisle family (A318/A319/A320/A321) ................................................................ 40 2.1. Tanks and capacities ................................................................................................... 40 2.2. Fuel System................................................................................................................. 43 2.3. CG travel during refueling ............................................................................................ 45 2.4. In-flight CG travel ......................................................................................................... 48 3. The Long-Range Family (A330/A340) ................................................................................ 49 3.1. Tanks and capacities ................................................................................................... 49 3.2. Fuel systems................................................................................................................ 52 3.3. CG travel during refueling ............................................................................................ 55 3.4. In-flight CG travel ......................................................................................................... 59 4. The Wide-Body Family (A300-600/A310) ........................................................................... 64 4.1. Tanks and capacities ................................................................................................... 64 4.2. Fuel Systems ............................................................................................................... 65 4.3. CG Travel during refueling ........................................................................................... 66 4.4. In-flight CG travel ......................................................................................................... 67 4.5. CG control system........................................................................................................ 67 C. Less Paper in the Cockpit Weight and Balance system.......... 69 1. Generalities ........................................................................................................................ 69 2. User interface – general presentation................................................................................. 70 2 Getting to Grips with Aircraft Weight and Balance WEIGHT AND BALANCE ENGINEERING A. Generalities.............................................................................. 75 1. Definitions........................................................................................................................... 75 1.1. Center of Gravity (CG) ................................................................................................. 75 1.2. Mean Aerodynamic Chord (MAC) ................................................................................ 75 2. Forces applied on flying aircraft .......................................................................................... 76 3. Influence of the CG position on performance...................................................................... 77 3.1. Impact on the stall speed ............................................................................................. 77 3.2. Impact on takeoff performance..................................................................................... 79 3.3. Impact on in-flight performance.................................................................................... 84 3.4. Impact on landing performance.................................................................................... 87 3.5. Summary ..................................................................................................................... 88 3.6. Conclusion................................................................................................................... 88 4. Certified limits design process ............................................................................................ 89 4.1. Certification requirements ............................................................................................ 90 4.2. Take-off Limitations...................................................................................................... 91 4.3. Aircraft stability and maneuverability Limitations .......................................................... 93 4.4. Final Approach Limitations........................................................................................... 98 4.5. Landing Limitations ...................................................................................................... 99 4.6. Limitation summary...................................................................................................... 99 4.7. Certified limits definition ............................................................................................. 100 4.8. SUMMARY : CG ENVELOPES.................................................................................. 104 B. Weight and Balance Manual .................................................. 108 1. Section 1 : Weight and balance control............................................................................. 108 1.1. 1.00: GENERAL......................................................................................................... 108 1.2. 1.10: LIMITATIONS.................................................................................................... 109 1.3. 1.20: FUEL................................................................................................................. 111 1.4. 1.30: FLUIDS............................................................................................................. 114 1.5. 1.40: PERSONNEL.................................................................................................... 114 1.6. 1.50: INTERIOR ARRANGEMENT ............................................................................ 115 1.7. 1.60: CARGO............................................................................................................. 115 1.8. 1.80: ACTIONS ON GROUND................................................................................... 117 1.9. 1.90: Examples .......................................................................................................... 117 2. Section 2 : Weight Report................................................................................................. 118 Getting to Grips with Aircraft Weight and Balance 3 WEIGHT AND BALANCE ENGINEERING C. Balance Chart Design............................................................ 121 1. Moment and Index definitions........................................................................................... 121 1.1. Moment...................................................................................................................... 121 1.2. Index.......................................................................................................................... 123 2. Index variation calculation (∆Index) .................................................................................. 125 2.1. ∆Index for one item.................................................................................................... 125 2.2. ∆Index for additional crew member ............................................................................ 125 2.3. ∆Index for additional weight on the upper deck .......................................................... 126 2.4. ∆Index for passenger boarding................................................................................... 127 2.5. ∆Index for cargo loading............................................................................................. 128 2.6. ∆Index for fuel loading................................................................................................ 130 3. operational limits determination ........................................................................................ 135 3.1. Calculation principle................................................................................................... 135 3.2. Margins determination method................................................................................... 135 3.3. Inaccuracy on initial data (DOW and DOCG) ............................................................. 138 3.4. Inaccuracy on items loading on board the aircraft (passengers, cargo, fuel) .............. 140 3.5. Inaccuracy due to CG computation method................................................................ 162 3.6. Item movements during flight impacting the aircraft CG position ................................ 167 3.7. Total operational margins determination .................................................................... 175 3.8. Takeoff, Landing, In-Flight operational limits determination........................................ 176 3.9. Zero Fuel limit determination...................................................................................... 178 4. Balance Chart Drawing principle....................................................................................... 181 4.1. ∆index scales or tables for loaded items .................................................................... 182 4.2. Operational limits diagram.......................................................................................... 184 5. The AHM560 .................................................................................................................... 186 5.1. Generalities................................................................................................................ 186 5.2. PART A: COMMUNICATION ADDRESSES............................................................... 186 5.3. PART B: GENERAL INFORMATION......................................................................... 187 5.4. PART C: AIRCRAFT DATA........................................................................................ 187 5.5. PART D: LOAD PLANNING DATA............................................................................. 189 D. Load and Trim Sheet software .............................................. 191 1. Introduction....................................................................................................................... 191 2. Objectives......................................................................................................................... 191 3. Software description......................................................................................................... 192 3.1. Unit system: ............................................................................................................... 192 3.2. Aircraft modifications: ................................................................................................. 192 3.3. Aircraft configurations: ............................................................................................... 193 3.4. Cabin layout: .............................................................................................................. 194 3.5. Operational margins customization ............................................................................ 195 4 Getting to Grips with Aircraft Weight and Balance LOADING OPERATIONS A. Loading Generalities.............................................................. 201 1. Load control...................................................................................................................... 201 1.1. Loading constraints.................................................................................................... 201 1.2. Load control organization and responsibilities............................................................ 201 1.3. Load control qualification............................................................................................ 204 2. Aircraft Weight .................................................................................................................. 205 2.1. Regulation.................................................................................................................. 205 2.2. Aircraft Weighing........................................................................................................ 206 3. Passenger weight ............................................................................................................. 207 3.1. General ...................................................................................................................... 207 3.2. Survey........................................................................................................................ 207 4. Loading Operations .......................................................................................................... 210 4.1. Preparation before loading......................................................................................... 210 4.2. Opening/Closing the doors......................................................................................... 215 4.3. On loading ................................................................................................................. 216 4.4. Off loading ................................................................................................................. 217 5. Loading Limitations........................................................................................................... 218 5.1. Structural limitations and floor panel limitations.......................................................... 218 5.2. Stability on ground – Tipping...................................................................................... 223 6. Securing of loads.............................................................................................................. 225 6.1. Introduction................................................................................................................ 225 6.2. Aircraft acceleration ................................................................................................... 225 6.3. Tie-down computation................................................................................................ 227 B. Special Loading ..................................................................... 241 1. Live animals and perishable goods................................................................................... 241 1.1. Generalities................................................................................................................ 241 1.2. Live animals transportation ........................................................................................ 243 1.3. Perishable goods ....................................................................................................... 246 2. Dangerous goods ............................................................................................................. 249 2.1. Responsibility............................................................................................................. 249 2.2. References................................................................................................................. 249 2.3. Definitions .................................................................................................................. 249 2.4. Identification............................................................................................................... 250 2.5. Classification.............................................................................................................. 250 2.6. Packing...................................................................................................................... 254 2.7. Marking and labeling.................................................................................................. 255 2.8. Documents................................................................................................................. 256 2.9. Handling and loading ................................................................................................. 258 2.10. Special shipments.................................................................................................... 259 Getting to Grips with Aircraft Weight and Balance 5 LOADING OPERATIONS C. Operational Loading Documents........................................... 263 1. Load and volume information codes ................................................................................. 263 1.1. Load Information Codes............................................................................................. 263 1.2. ULD Load volume codes............................................................................................ 263 1.3. Codes used for loads requiring special attention........................................................ 264 2. Loading Instruction / Report (LIR)..................................................................................... 265 2.1. Introduction 265 2.2. Manual LIR 266 2.3. EDP LIR..................................................................................................................... 269 3. Container/Pallet distribution message (CPM) ................................................................... 271 4. Loadsheet......................................................................................................................... 273 4.1. Introduction................................................................................................................ 273 4.2. Manual loadsheet....................................................................................................... 274 4.3. EDP Loadsheet.......................................................................................................... 278 4.4. ACARS loadsheet ...................................................................................................... 279 5. Balance calculation methods ............................................................................................ 280 5.1. Introduction................................................................................................................ 280 5.2. Manual balance calculation method ........................................................................... 280 5.3. EDP balance calculation methods 288 A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 7 S Y S T E M S SYSTEMS CARGO SYSTEMS INTRODUCTION Airbus aircraft are designed for passenger civil air transport with a passenger cabin on the upper deck. The lower deck of the airplane is dedicated to passenger luggage as well as additional freight transportation. So at the end of the 60’s, the A300 was originally designed to accommodate, with a semi-automatic, electrically powered cargo loading system, the Unit Load Devices that were already standardized at that time for the B747, considering that the cargo area was too great for it to be loaded manually. This solution was later used for to all the other long- range programs. On the single aisle family two cargo loading solutions are proposed to the operators either manual bulk loading or semi-automatic, electrically powered cargo loading system accommodating Unit Load Devices derived from the larger aircraft ULDs. The following chapter describes the cargo loading areas on Airbus aircraft and the systems related to cargo holds. As an introduction the first paragraph is dedicated to Unit Load Devices description. A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 9 S Y S T E M S A. CARGO SYSTEMS 1. TYPE OF ULDS AND CONFIGURATION 1.1. History When the first Boeing 747 went into service in 1970, the air transport industry faced a dramatic change of ground-handling culture. In fact, the lower-deck capacity of the 747 was too great for it to be loaded manually. Baggage and cargo had to be accommodated in Unit Load Devices (ULDs), which had previously only been used for freighter aircraft. The 747 was originally designed to accommodate the 96in square cross-section of the ISO standard ‘marine’ containers on the main deck, which determined the overall shape and size of the fuselage. The space remaining in the lower deck, after satisfying the main deck requirement determined the basic dimensions and shape of the lower-deck containers. Most carriers at that time used 88in x 125in pallets on freighter aircraft. The 747s lower-deck system was required, therefore, to be able to accept the 125in dimension across the width of the lower deck. Then the lower deck height dictated the maximum height for ULDs (64in). For ease of handling, the new baggage containers were smaller than cargo containers and were loaded in pairs, each unit occupying half the width of the compartment floor. The baseplate dimensions of the half-width container were set at 60.4 x 61.5in. Having been of such service to the industry in developing a ‘standard’ for lower deck ULD equipment, Boeing then, unaccountably, introduced the 767, which first flew in 1981, which used several completely different sizes of ULD. With this background of evolution and airframe manufacturer influence, although many of the ULD sizes in use are ‘standard’ in terms of certain critical dimensions, incompatibilities do still exist and many different ULD types are in service. The basic reference document for ULD base sizes is a National Aerospace Standard produced by the Aerospace Industries Association of America, in accordance with the requirements of federal Aviation Regulation-Part25 (FAR25)-Airworthiness Standards: Transport Category Aeroplanes. This document, drafted with input from the major U.S. airframe manufacturers, was designated NAS3610. The document was approved by the Federal Aviation Administration (FAA) in 1969 and entitled: minimum Airworthiness requirements and test conditions for Certified Air Cargo Unit Load devices. The primary objective was to provide requirements designed to ensure the ability of ULDs and their in-aircraft restraint-systems to contain their load under the influence of in-flight forces. Although NAS3610 is an airworthiness certification document, the fact that it reflects mandatory requirements and details the baseplate dimensions of all ULDs types dictate that all ULD standards should refer to it. NAS3610 only considers the ULD baseplate. There are a variety of different contours that may be attached to any one baseplate size. It is the responsibility of the owner of an aircraft ULD to have provisions for the maintenance of such units to the effect that they are kept in an airworthy condition. Airbus does not differentiate between so-called certified or non-certified containers. It is not required that a container actually undergoes a certification process, however the container has to fulfil the same requirements as a certified container. A. CARGO SYSTEMS 10 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 1.2. IATA identification code for Unit Load Devices (ULDs) There is a large number of ULDs in operations today. Taking into account all the characteristics corresponding to a particular ULD has therefore developed an identification Code. This Code contains essential data to describe each ULD and for further technical information the reference is the IATA ULD Technical Manual. The purpose of the following paragraph is to explain quickly the method of ULD marking and numbering. • IATA Identification Code The Identification Code gives each unit an individual identification and allows the easy exchange of the information contained in the marking of units. The IATA Identification Code consists in nine characters composed of the following elements: Position Type description 1 ULD Category 2 Base Dimensions 3 Contour and Compatibility 4,5,6 and 7 Serial number 8 and 9 Owner/Registrant Only the three first letters are necessary to identify the ULD. • TYPE CODE (Positions 1,2 and 3) • Position 1 Position 1 is used to describe the general type of the unit considering only the following characteristics: − Certified as to airworthiness or non-certified. − Structural unit or non-structural. − Fitted with equipment for refrigeration, insulation or thermal control or not fitted for refrigeration, insulation or thermal control. − Also considering specific units: containers, pallets, nets, pallet/net/non-structural igloo assembly. Code Letter ULD Category A Certified aircraft container D Non-Certified aircraft container F Non-Certified aircraft pallet G Non-Certified aircraft pallet net J Thermal non-structural igloo M Thermal non-certified aircraft container N Certified aircraft pallet net P Certified aircraft pallet R Thermal certified aircraft container U Non-structural container H Horse stalls K Cattle stalls V Automobile transport equipment X Reserved for airline internal use Y Reserved for airline internal use Z Reserved for airline internal use A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 11 S Y S T E M S • Position 2 This position makes reference to the Base Dimensions of the ULD. Series Base dimensions (and compatible nets when applicable) length width length width A 2235 x 3175 mm 88 x 125 in B 2235 x 2743 mm 88 x 108 in E 1346 x 2235 mm 53 x 88 in F 2438 x 2991 mm 96 x 117.75 in G 2438 x 6058 mm 96 x 238.5 in H 2438 x 9125 mm 96 x 359.25 in J 2438 x 12192 mm 96 x 480 in K 1534 x 1562 mm 60.4 x 61.5 in L 1534 x 3175 mm 60.4 x 125 in M 2438 x 3175 mm 96 x 125 in N 1562 x 2438 mm 61.5 x 96 in P 1198 x 1534 mm 47 x 60.4 in Q 1534 x 2438 mm 60.4 x 96 in R 2438 x 4938 mm 96 x 196 in X Miscellaneous sizes largest dimension between 2438 mm and 3175 mm (between 96 in and 125 in) Y Miscellaneous sizes largest dimension lower than 2438 mm (96 in) Z Miscellaneous sizes largest dimension above 3175 mm (125 in) A. CARGO SYSTEMS 12 Getting to Grips with Aircraft Weight and Balance S Y S T E M S • Position 3 The Position 3 corresponds to the type of contour and describes if the ULD is forklift compatible or not. The loading contours have been sequentially numbered and the individual aircraft ULDs are coded and marked according to the type of aircraft in which they can be carried. A full description of the aircraft contours is contained in the IATA ULD Technical Manual. Here are the main contours and their letters. 9 6 i n ( 2 4 3 8 m m ) 9 0 i n ( 2 2 8 6 m m ) 48in (1219mm) M A / B A - Non-Forkliftable B - Forkliftable M 2.12 in(54mm) 79 in(2007mm) 92 in(2337mm) 6 4 i n ( 1 6 2 6 m m ) 4 6 i n ( 1 1 6 8 m m ) G E / N C E-Non-Forkliftable N-Forkliftable G C 2.12 in(54mm) or 4.25 in (108mm) 96 in(2438mm) 80 in(2032mm) 6 4 i n ( 1 6 2 6 m m ) 4 6 i n ( 1 1 6 8 m m ) H A / B U / F / H U F 93 in(2362mm) A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 13 S Y S T E M S 62.5 in(1588mm) 6 4 i n ( 1 6 2 6 m m ) P P 41.3 in (1049mm) 15.3 in (389mm) 62.5 in(1588mm) 6 4 i n ( 1 6 2 6 m m ) K Z Z / K 8 2 i n ( 2 0 8 3 m m ) A. CARGO SYSTEMS 14 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 1.3. ULDs among the AIRBUS fleet ULD Type CONTAINERS Base Dimension ATA IATA Length Width Height Typical Volume (without shelves) LD3 AKE (V3) 60.4 in (1534 mm) 61.5 in (1562mm) 64 in (1626mm) 4.3 m 3 - 151 ft³ LD3-46 AKG 60.4 in (1534 mm) 61.5 in (1562mm) 46 in (1168mm) 3.1 m 3 - 109 ft³ LD3-46W AKH 60.4 in (1534 mm) 61.5 in (1562mm) 46 in (1168mm) 3.68 m 3 – 130 ft³ LD1 AKC (V1) 60.4 in (1534 mm) 61.5 in (1562mm) 64 in (1626mm) 4.7 m 3 - 166 ft³ LD6 ALF (W3) 60.4 in (1534 mm) 125 in (3175 mm) 64 in (1626mm) 8.9 m 3 - 314 ft³ s t a n d a r d LD3-40/45 H 39.75 in (1010mm) 61.5 in (1562mm) 40 - 45 in (1016-1143mm) 2.42 m 3 - 96 ft³ LD2 DPE 60.4 in (1534 mm) 47 in (1194 mm) 64 in (1626mm) 120 ft³ LD4 DQP 60.4 in (1534 mm) 96 in (2432 mm) 64 in (1626mm) 202 ft³ o p t i o n LD8 DQF 60.4 in (1534 mm) 96 in (2432 mm) 64 in (1626mm) 245 ft³ PALLETS Base Dimension ATA IATA Length Width Height Vol. LD9 PMx 96 in (2438 mm) 125 in (3175 mm) 64 in (1626mm) 10.9 m 3 - 385 ft³ (contour P) 14.6 m 3 - 515 ft³ (contour F) LD7 PAx (A2) 88 in (2235 mm) 125 in (3175 mm) 64 in (1626mm) 10 m 3 - 353 ft³ (contour P) 13.4 m 3 - 473 ft³ (contour F) PLx 60.4 in (1534 mm) 61.5 in (1562 mm) 64 in (1626mm) 7.2 m 3 - 254 ft³ (contour F) s t a n d a r d PKx 60.4 in (1534 mm) 61.5 in (1562 mm) 46 in (1168mm) 3.5 m 3 - 123 ft³ (contour P) A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 15 S Y S T E M S Number of ULD per cargo hold FWD/AFT/BULK ULD Max weight ATA/ IATA A318 A319 A320 A321 A310 A300- 600 A330- 200 A330- 300 A340- 300 A340- 200 A340-500 A340- 600 8/6/1* 12/10/1* 14/12/1* 18/14/1* 14/12/1* 18/12 18/10**** 24/18 LD3 / AKE (V3) 3500lb (1587kg) 2/2**/0 3/4**/0 5/5**/0 8/6/1* 12/10/1* 14/12/1* 18/14/1* 14/12/1* 18/12 18/10**** 24/18 LD3- 46 / AKG 2500 lb (1134kg) 2/2**/0 3/4**/0 5/5**/0 4/3/1* 6/5/1* 7/6/1* 9/7/1* 7/6/1* 9/6 9/5**** 12/9 LD3- 46W / AKH 2500lb (1134kg) 4/3/0 6/5/0 7/6/0 9/7/0 7/6/0 9/6 9/5**** 12/9 LD1 / AKC (V1) 3500lb (1587kg) 4/3/0 6/5/0 7/6/0 9/7/0 7/6/0 9/6 9/5**** 12/9 LD6 / ALF (W3) 7000lb (3174kg) 0/1** s t a n d a r d LD3- 40/45 / H 1660lb (753kg) 0/8*** 0/10*** 0/8*** LD2 / DPE 2700lb (1224kg) 0/4*** 0/5*** 0/4*** LD4 / DQP 5400lb (2449kg) 0/4*** 0/5*** 0/4*** o p t i o n LD8 / DQF 5400lb (2449kg) 3/0 4/0 4/4 6/4 5/4 6/4 6/3**** 8/6 PMx 11250lb (5103kg) 3/0 4/0 4/4 6/5 5/4 6/4 6/3**** 8/6 Pax (A2) 10200lb (4626kg) 4/3/0 6/5/0 7/6/0 9/7/0 7/6/0 9/6 9/5**** 12/9 PLx 7000lb (3174kg) 2/2 3/4 5/5 8/6 12/10 14/12 18/14 14/12 18/12 18/10**** 24/18 P A L L E T PKx 3500lb (1587kg) *option : additional container in bulk cargo compartment. **option : the basic version is designed for bulk loading. ***option : eight (or ten) containers plus four LD3 in aft compartment. ****option : for A340-500 equipped with 7 frames Rear Center Tank (RCT) A. CARGO SYSTEMS 16 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 79 in (2007m m ) 60.4 in (1534m m ) 61.5 in (1562m m ) * 4 6 i n ( 1 1 6 8 m m ) CONTAINER AKG IATA ULD Code: AKG Classification ATA: LD3-46 Aircraft: A320 family and interlining Volume:110 ft³(3.1m³) Weight limitations: 2500 lb (1134 kg) 6 4 i n ( 1 6 2 6 m m ) 94 in (2337m m ) 61.5 in (1 56 2m m ) 60.4 in (1534m m ) CONTAINER AKC IATA ULD Code: AKC Classification ATA: LD1 Also known as AVC, AVD, AVK, AVJ. Aircraft: A310, A300, A330, A340. Volume: 159 to 173 ft³(4.5 to 4.9m³) Weight limitations: 3500 lb (1587 kg) CONTAINER AKH IATA ULD Code: AKH Classification ATA: LD3-46W Also known as DKH. Aircraft: A320 family and interlining Volume: 127 ft³(3.6m³) Weight limitations: 2500 lb (1134 kg) 96 in (2438m m ) * 4 6 i n ( 1 1 6 8 m m ) 6 1 .5 in (1 5 6 2 m m ) 60.4 in (1534m m ) Additional CONTAINER A319 IATA ULD Code: H Classification ATA: LD3-40/45 Aircraft: A319 Volume: 80 ft³(2.25m³) Certified MGW limit: 1660 lb (753 kg) 4 5 i n ( 1 1 6 8 m m ) 39.75 in (1010 m m ) 96 in (2438m m ) 6 1 .5 in (1 5 6 2 m m ) CONTAINER AKE IATA ULD Code: AKE Classification ATA: LD3 Also known as AVA, AVB, AVC, AVK, DVA, DVE, DVP, XKS,XKG. Aircraft: A310, A300, A330, A340. Volume: 145 to 158 ft³(4.1 to 4.47m³) Weight limitations: 3500 lb (1587 kg) 6 4 i n ( 1 6 2 6 m m ) 79 in (2007mm) 6 0 .4 in (1 5 3 4 m m ) 6 1 .5 in (1 5 6 2 m m ) CONTAINER ALF IATA ULD Code: ALF. Classification ATA: LD6 Aircraft: A310, A300, A330, A340. Volume: 316 ft³(8.9m³) Weight limitations: 7000 lb (3175 kg) 6 4 i n ( 1 6 2 6 m m ) 160 in (4064m m ) 1 2 5 in (3 1 7 5 m m ) 60.4 in (1534m m ) NB: * means that, for those two containers, this dimension varies between 44 in and 46 in. Some airlines prefer the 45 in container. A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 17 S Y S T E M S 6 4 i n ( 1 6 2 6 m m ) 61.5 in (1562mm) 4 7 in (119 4m m ) 6 0.4 in (15 34m m ) CONTAINER DPE IATA ULD Code: DPE Classification ATA: LD2. Also known as APA, DPA. Aircraft: A330, A340. Volume: 120 ft³(3.4m³) Weight limitations: 2700 lb (1224 kg) 6 4 i n ( 1 6 2 6 m m ) 9 6 in (2 4 3 8 m m ) 6 0 .4 in (1 5 3 4 m m ) CONTAINER DQP IATA ULD Code: DQP Classification ATA: LD4 Volume: 202 ft³(5.7m³) Weight limitations: 5400 lb (2449 kg) 96 in (1 1 94 m m ) 125 in (3175 m m ) 6 4 i n ( 1 6 2 6 m m ) 6 0 .4 in (1 5 3 4 m m ) CONTAINER DQF IATA ULD Code: DQF. Classification ATA: LD8 Also known as ALE, ALN, DLE, DLF, DQP. Volume: 245 ft³(6.9m³) Weight limitations: 5400 lb (2449 kg) 1 2 5 in (3 1 7 5 m m ) 6 4 i n ( 1 6 2 6 m m ) 9 6 in (2 4 3 8 m m ) PALLET PMx IATA ULD Code: PMx Classification ATA: LD9 Also known as P6P, P6A, P6Q, PMA, PMC, PMP, PQP. Aircraft: A310, A300, A330, A340. Volume: 407 ft³(11.5m³) Weight limitations: 11250 lb (5103 kg) 1 2 5 in (3 1 7 5 m m ) 6 4 i n ( 1 6 2 6 m m ) 8 8 in (2 2 3 5 m m ) PALLET PAx IATA ULD Code: Pax Classification ATA: LD7 Also known as PAA, PAG, PAJ, PAP, PAX, P1A, P1C, P1D, P1G. Aircraft: A310, A300, A330, A340. Volume: 372 ft³(10.5m³) Weight limitations: 10200 lb (4626 kg) 61 .5 in (156 2m m ) 4 6 i n ( 1 1 6 8 m m ) 60.4 in (1534m m ) PALLET PKx IATA ULD Code: PKx Volume: 85 ft³(2.4m³) Aircraft: A320 family Weight limitations: 2500 lb (1134 kg) Certified MGW limit: 3500 lb (1587 kg) A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 19 S Y S T E M S 2. CARGO HOLDS DESCRIPTIONS All Airbus aircraft lower decks are divided into 3 cargo holds : forward (FWD), AFT and BULK. FWD and AFT holds are divided into 1 or 2 compartments, each compartment being made of several loading positions defining the position of each type of ULD or the position of bulk cargo loads. The cargo holds position arrangement depends on the aircraft fuselage length. 2.1. Bulk cargo system For the A320 family aircraft the basic way to load cargo is to load it in bulk. For any Airbus aircraft the most rear cargo hold (BULK : compt 5) is also loaded in bulk. These holds are equipped with adequate cargo and lining components. 2.1.1. Cargo components a) Partition nets These nets are used for cargo loading areas separation. They have fixed locations in each cargo hold and dedicated attachment points on the ceiling and side-wall linings and on the floor panels. There is also a divider net separating AFT and BULK cargo holds. This divider net has to be linked with a tarpaulin. A. CARGO SYSTEMS 20 Getting to Grips with Aircraft Weight and Balance S Y S T E M S b) Door net These nets are used to delimit the entrance door area which must remain unloaded. c) Attachment point Attachment points are used to fasten the nets. They are located on the ceiling and side-wall linings and on the floor panels. Attachment points in the side-wall and ceiling linings are for nets fastening only. Attachment points on the floor panels that are not used for nets fastening can be used for load restraint. d) Tie-down point Tie-down points are used to restraint cargo item(s) movement in the cargo hold. 2.1.2. Lining components a) Floor panel b) Side wall lining c) Ceiling d) Partition wall Each panel has a defined maximum static area load. These loads are not exceeded if the maximum loads per position and per holds are not exceeded and if loads, which due to their geometry or weight may damage the panel, are tied down at loading. A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 21 S Y S T E M S 2.2. Cargo Loading Systems (CLS): The 2-aisle aircraft family is equipped with a semi-automatic, electrically powered cargo loading system in the FWD and AFT cargo holds. For A320 family, except for the A318, an option is available to have the cargo loading system installed. This cargo loading system is compatible with ULDs designed to meet the class II requirements of the specification NAS3610 and provides individual ULD baseplate restraint. It offers a real flexibility for loading as any position can be loaded or remain empty. Locking and unlocking of ULDs inside the cargo compartments is carried out manually. ULDs which do not fit into the restraint system due to their geometry can be loaded but they must be handled in such a manner that neither the ULD nor the items loaded on it will endanger the aircraft during the whole flight. The cargo loading system allows manual loading and offloading of the ULDs if the power drives are inoperative for any reason. Simultaneous loading and offloading of the FWD and the AFT holds is possible provided that the stability criteria are met. The cargo loading system is equipped with rollertrack mounted self-lifting electrical Power Drive Units (PDU) installed for the lateral and longitudinal movement of ULDs and controlled by a joystick located in the doorway. The following paragraphs provide detailed information about conveyance components, guides and restrains, power drive and control component. 2.2.1. Conveyance components: a) Ballmats and Ball Transfer units in entrance area: Ballmats and ball strips are installed in the forward and aft cargo door entrance area. The ballmats and strips are equipped with ball transfer units installed in a framework, they allow multi- directional and low friction movements of ULDs in the cargo door area. Ballmats and Ball Transfer units in entrance area of A330/A340 A. CARGO SYSTEMS 22 Getting to Grips with Aircraft Weight and Balance S Y S T E M S b) Roller tracks: The roller tracks are installed in longitudinal direction, used for longitudinal transport of ULDs. The roller tracks are extruded profiles, equipped with transport rollers, endstops and XZ-latches. At certain position, the roller tracks are additionally equipped with power drive units and proximity switches below the XZ-latches allowing powered transportation of ULDs. In these roller tracks braking rollers are also installed to prevent inadvertent ULD movement. Roller track Transport roller 2.2.2. Power drive and control components: a) Power drive units: The Power Drive Unit (PDU) consists of an electrical motor, a gear drive and a rubber coated roller, mounted on a rolling axle. It is used to move the ULDs in longitudinal and lateral direction. All PDUs are activated via signal from the control system. It provides a towing force, sufficient to drive the ULDs in different directions. When the PDU is switched off, the drive roller lowers automatically to its rest position, 3 mm below system height. Roller track PDU Drain outlet Ball mat PDU, “Self - lift” type PDU sensor Outside ball mat PDU, “Spring - Lift” type A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 23 S Y S T E M S b) Control components and control panel: Loading and offloading with the lower deck cargo loading system is managed by control panels located at FWD and AFT cargo doors, that are equipped with a power ON-OFF switch to activate the CLS and a joystick to determine the direction of movement of the PDUs. On A340-500 and A340-600 aircraft an additional joystick is installed on the roof of the entrance area. From this joystick it is possible to control the all PDUs except those in the ballmat area. In order to avoid any unexpected or dangerous ULD movement in the cargo hold some limitation systems are available : − limit switches below the XZ-latches stopping the PDU power when the ULD has reached its limit. − a switch at each door sill latch interrupting power supply for the CLS each when the latch is raised and preventing door operations when the latch is lowered. Additional joystick A. CARGO SYSTEMS 24 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2.2.3. Guides and restraints: a) Door sill: Door sill latch units are installed in the FWD and AFT cargo door areas. Each door sill latch consists of: − a YZ-latch, which allows to latch the ULDs positioned in the door entrance area. − an overrideable Y-latch which prevents inadvertent roll out of ULDs during loading and off-loading. − a guide roller which is used to transfer of ULDs between the loader and the ballmat area. Guide roller Overrideable Y-latch YZ-latch The YZ-latch is operated manually. It can be lowered by pressing a red lever at the side of the unit and can be raised by being pulled up by hand. Each lever of the door sill latch units is electrically monitored by a limit switch to ensure that the cargo door cannot be closed when the YZ-latch is in its lower position and that the CLS is not powered closed when the YZ-latch is in its up position. YZ-latch lowered YZ-latch in up position The overrideable Y-latches are spring loaded and operated automatically or manually. They are overrideable in loading direction, returning to the raised position once the ULD has passed over, to prevent inadvertent roll out. Before ULD offloading, the Y-latch has to be lowered manually by means of a handle located on the cargo loading system control panel. When the handle is pushed down, a hydraulic damper delays the Y-latch raising to allow ULD unloading. A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 25 S Y S T E M S b) Entrance guides: The door entrance guides provide a correct guidance on the ballmat during loading or offloading of ULDs and prevent impact to the doorframe. Entrance guides system is made of guides acting in different directions : − a mechanical Z-guide is installed for guidance of ULD baseplates under the endstops. − a spring loaded Y-guide is installed with a guide roller, which provides sufficient clearance between ULD’s baseplate and the door frame during loading and offloading. − retractable Y-guides prevent the ULD’s from turning while entering the compartment. To transport the ULDs to their final position those guides have to be unlocked by operating a toggle switch on the entrance control panel. Entrance guides AFT door Entrance guides FWD door Retractable Y-guides c) Fixed YZ-latches and side guides opposite of cargo door: The fixed YZ-latches serve to guide in X-direction and to lock ULDs in Y- and Z-direction. These latches are located at each frame on both sides of the cargo compartments. A vertical guide roller is installed in the YZ-latch. Each YZ-latch is equipped with a tie-down point, designed to a maximum load of 2000 lbs (890daN) or 4000 lbs for A340-500 and A340-600 in any direction. Additional side guides are basically installed opposite of each cargo door to align ULDs and optional continuous side guides are installed all along the cargo holds. Tie down point Fixed YZ-latch Optional Continuous Side Guides Fixed YZ-latch Tie down point A. CARGO SYSTEMS 26 Getting to Grips with Aircraft Weight and Balance S Y S T E M S d) Overrideable YZ-latches (A310, A300, A330, A340): Overrideable YZ-latches, also known as “butterfly”, are provided to lock half-size containers in Y- and Z-direction. These latches are attached to the structure at aircraft centerline. During loading of full size containers the latches are overridden. The two latch claws are spring loaded so they raise again when the ULD has moved on. Overrideable YZ-latches e) Overrideable Y-guide (splitter): The overrideable Y-guides are used to separate half-size ULDs during loading and offloading. They are located in the entrance area of AFT and FWD holds. When loading ULDs they can be lowered manually by foot beneath the level of the cargo loading system then when half size containers are loaded they can be pulled up using the control panel joystick in order to separate the ULDs. Overrideable Y-guide A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 27 S Y S T E M S f) XZ-latches: The XZ-latches are used to lock the ULDs in X- and Z-direction. They are fitted to the roller tracks. They are spring loaded and operated manually. Limit switches are installed underneath some of the XZ-latches. These switches serve to cut off the power supply of the associated PDUs when the applicable latch is in the locked (up) position and to restore PDU power supply when the latch is in lowered position. To unlock/lower the latch the pawl marked “Press to unlock” needs to be pressed this can be achieved by foot pressure. The latch is locked by hand by pulling the pawl upwards. Depending on the cargo hold configuration single, double or triple latches may be installed in order to accommodate any kind of ULD loading. Single latch Double latch Triple latch g) Endstops: The fixed XZ-endstops at the extremities of each cargo hold are used to lock ULDs in the X- and Z-direction. A. CARGO SYSTEMS 28 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2.3. Cargo loading system failure cases In case of failure or malfunctions of some of the cargo loading system equipments: nets; tie down points, latches; …, some limitations in the allowed cargo weight per position may appear. The WBM details these different limitations in chapter 1.10. In case of malfunctioning ULD’s and aircraft structure. Malfunctioning equipment should be replaced as soon as possible. Failure of a latch may require weight reduction of the ULD forward and aft of the latch of LH and RH of the latch. Example : A330-200 : In case of XZ-latch failure between position 13L and 21L, ULD weight must be reduced to 0 kg on both position. A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 29 S Y S T E M S 2.4. Additional Cargo holds related systems 2.4.1. Cargo hold doors In most Airbus aircraft there are three cargo doors: one for the forward compartment, one for the aft cargo compartment and one for the bulk compartment. However the shorter A318 and A319 do not have the bulk cargo door.The forward and the aft cargo doors open to the outside and the bulk cargo door opens to the inside. Bulk Cargo Door CLEAR OPENING DIMENSIONS A318 A319 A320 A321 A310/A300 A330/A340 F W D D O O R 1.24 x 1.28 m (48.8x50.5 in) 1.23 x 1.82 m (48.6x71.5 in) 1.23 x 1.82 m (48.6x71.5 in) 1.23 x 1.82 m (48.6x71.5 in) 1.69 x 2.70 m (66.8x106 in) 1.70 x 2.70 m (66.9x106 in) A F T D O O R 1.23 x 1.28 m (48.6x50.5 in) 1.23 x 1.82 m (48.6x71.5 in) 1.2 x 1.82 m (48.6x71.5 in) 1.23 x 1.82 m (48.6x71.5 in) 1.68 x 1.81 m (66.3x71.3 in) 1.68 x 2.72 m (66.1x107 in) B U L K D O O R No door No door 0.81 x 0.95 m (32 x 37 in) 0.88 x 0.95 m (34 x 37 in) 0.64 x 0.95 m (25.1x37.4 in) 0.64 x 0.95 m (25x37.4 in) A. CARGO SYSTEMS 30 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2.4.2. Lining and decompression (All Airbus aircraft): The ceiling, sidewalls and floors of the cargo compartment have fire and impact resistant linings complying with “JAR/FAR 25 Amendment 60”. The floor panels and the linings are of sandwich type, manufactured from honeycomb, prepreg layers and protection foil or metal sheet. The installed linings and floor panels are designed for the following: − Handling loads from loading personnel. − Surface finish in light color. − Quick release features necessary for accessibility. − Rapid decompression requirements according to FAR/JAR. − Leak proof requirements for class C compartments according to FAR/JAR. − Flammability requirements according to FAR/JAR. − Low smoke and toxicity requirements. The sidewalls and partitions are equipped with rapid decompression panels. Each decompression panel is enclosed within a frame and is held in place by decompression assemblies. Decompression panels In case of “blow in” spring loaded snappers are pushed back, in case of “blow out” the frame of the decompression panel brakes to allow decompression panel displacement. “Blow out” case “Blow in” case A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 31 S Y S T E M S 2.4.3. Drainage (All Airbus aircraft): To prevent accumulation of water in the cargo compartments, numerous drain-outlets are provided in forward and aft cargo compartments and in the bulk compartment floor. Drain funnels are installed in the roller tracks, in sumps and in the floor in front of slushing dam. The drain outlets consist of a mounting housing, acting as a coarse filter, which contains a sponge filter element. Hoses are connected to the drain outlets, leading to the bilge area, which is provided, with drain valves. 2.4.4. Cargo compartment lighting (All Airbus aircraft): A separate lighting system is installed in each cargo compartment. All lights are manually controlled by means of switches. The control switch is installed adjacent to the cargo door for the respective compartment. Each cargo hold is provided with a minimum light level of 50 lux at the hold floor. For the lighting of the loading area, a spotlight is installed in each door ceiling area. The loading area light is sufficient to allow reading of labels on the ground loading equipment, placed near to the cargo door. A. CARGO SYSTEMS 32 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2.4.5. Heating and ventilation a) in bulk cargo compartment (A310/A300/A330/A340): Cabin ambient air is supplied to the bulk cargo compartment through a distribution duct along the left-hand side of the compartment. On request, an electrical heater can heat the air. The air is extracted from the bulk compartment by an electrical fan through vents near ceiling on the right-hand side. The extracted air from the bulk cargo compartment is passed under the bulk compartment floor to provide floor heating. In the bulk cargo compartment, isolation valves are fitted in the inlet and outlet ducts to isolate the cargo compartment in case of smoke warning. BULK Overboard Cabin Ambient Air Inlet Isolation Valve Inlet Isolation Valve ELECTRICAL FAN HEATER Air Extraction Fan Air Extraction Fan A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 33 S Y S T E M S b) in FWD and/or AFT cargo compartment (all aircraft, optional): Ventilation system is based on air suction provided by an extraction fan or by a venturi tube in flight when the pressure difference is sufficient. In the case of temperature regulation, the air enters pressurized and conditioned. The air enters the compartment through one side wall and ceiling and is extracted on the other side. Temperature control is provided on top of the ventilation by adding cold or hot air respectively from the packs or hot air manifold. The hot air supply is controlled by a trim valve which regulates the temperature in the compartment. To decrease the compartment temperature, the cabin ambient air can be mixed with cold air from the packs via a cold air valve. This valve has three positions to adjust the quantity of cooled conditioned air. In the event of smoke detection, the isolation valves, trim air valve, cold air valve are automatically closed and the extraction fan is switched OFF. A cockpit temperature selector and a cockpit cooling mode selector control temperature. It is possible to select temperatures within the range of 5 DEG C and 25 DEG C (41 DEG F and 77 DEG F). FWD Overboard Cabin Ambient Air Cabin Ambient Air Trim air valve (hot air supply) Trim air valve (hot air supply) Cold air valve Cold air valve An additional option is available which ensures proper ventilation in the bulk and main cargo compartments during ground time when respective cargo doors are open. In the bulk cargo compartment, the basic fan heaters can be controlled by an ON/OFF switch on the aft compartment servicing panel in order to activate the blowing function when the aircraft is on ground and the cargo compartment door is fully open. The heating function is deactivated in this operation. In the main cargo compartment, this option uses the same ventilation as in flight nevertheless; the following aircraft conditions and activities are necessary: − Packs running − Forward cooling selector in cockpit overhead panel in "NORM" position. A. CARGO SYSTEMS 34 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2.4.6. Fire protection: We consider two airworthiness requirements: − Class “C” (FAR 25.857(c)): A class “C” cargo or baggage compartment is one in which: 1- There is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station 2- There is an approved built-in fire-extinguishing system controllable from the pilot or flight engineer station 3- There are means to exclude hazardous quantities of smoke, flames or other noxious gases from any compartment occupied by the crew or passengers 4- There are means to control ventilation and drafts within the compartment so that the extinguishing agent used can control any fire that may start within the compartment. 5- {Reserved} To sum up, it is a compartment, which has a smoke detection and an automatic fire extinguishing system and burn through resistant lining. A. CARGO SYSTEMS Getting to Grips with Aircraft Weight and Balance 35 S Y S T E M S • The fire protection system consists of two sub-systems: a) A dual loop smoke detection system: Ionization-type smoke detectors are installed in cavities in the ceiling of each compartment. Each cavity contains two detectors. Detectors are controlled and operated by the Smoke Detection Control Unit (SDCU) as a dual loop system using and/or logic principle requiring that, in each compartment, signaling from two detectors is required to produce a smoke warning. With a detector failure, the system reverts to a single-loop operating condition. Note: Smoke detectors: When combustion gazes enter the detector, they change the voltage of an ionization chamber, which the sampled air passes through. An electronic circuit inside the detector estimates this change, amplifies it and transmits the information to the flight deck) Smoke detectors and Extinguishing nozzle b) A Fire extinguishing system: This system consists of two fire suppression bottles (just one bottle for the A320 family) which are installed behind the sidewall lining, one without flowmeter and the second with flowmeter. The discharged cartridges are electrically ignited by guarded switches located on the overhead panel. When the bottle content is discharged, a pressure switch activates lamps in the cockpit to confirm that the agent has been discharged. The extinguishing agent (Halon 1301) is discharged to either the forward or aft lower deck holds.(see picture above). Discharge cartridges with flowmeter Discharge cartridges without flowmeter B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 37 S Y S T E M S FUEL SYSTEMS INTRODUCTION This part describes general aspects of the aircraft fuel systems such as fuel capacities, fuel control computers as well as the impact on CG position (CG movement during refueling and CG movement in flight). All Airbus aircraft fuel systems described in this part have some common characteristics, the most obvious being the location of the fuel tanks. These tanks are located in the wings, in the fuselage (center tank and additional center tanks – ACT) and in a trim tank located in the THS (except for A320 family and some A300/A310 aircraft). Due to some structural issues common to all aircraft, the refueling and defueling sequences follow the same guidelines. Fuel computers on board the aircraft manage the fuel sequence. B. FUEL SYSTEMS 38 Getting to Grips with Aircraft Weight and Balance S Y S T E M S B. FUEL SYSTEMS 1. GENERALITIES The main part of the aircraft weight and most particularly the payload is located in the fuselage. In flight, this weight is balanced by the lift created mainly on the wings. This distribution generates a bending moment around the wing root. This has a strong impact on the aircraft structure and leads to define a Maximum Zero Fuel Weight (MZFW) in order to limit the stress at these locations. Bending moments Important structural strain Lift 2 Lift 2 Weight = mg On the one hand, the weight of the fuel tanked in the wings balances the effect of the lift and thus reduces the bending moment. On the other hand, the fuel in the fuselage is an extra load the wings have to create lift for. So, fuel has to be kept in the wing as long as possible. Bending moments Lift 2 Lift 2 m fuselage g m fuel g m fuel g B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 39 S Y S T E M S This is the reason why the wing tanks are the first tanks to be filled and the last ones to be emptied and this no matter the aircraft type. Moreover, as the wing tanks are generally divided into outer and inner wing tanks (except on A321), the outer tank is filled first in order to bring the g m fuel vector further out. However, it is worth pointing out that this rule is only applicable to a certain extent : too much weight in the outer tanks creates some structural strain on the wings on ground (ie when not balanced by the lift). On top of this general considerations, each aircraft family (ie. A318/A319/A320/A321, A330/A340 and A300-600/A310) has its own characteristics. That is why this part presents the following aspects for each aircraft family separately: − Fuel tanks: location and capacities − Fuel systems: engine feed system, control and indication − CG travel during refueling: refueling sequence and resulting fuel vector − In-flight CG travel: defueling sequence, in-flight fuel transfers − CG control system (when applicable) B. FUEL SYSTEMS 40 Getting to Grips with Aircraft Weight and Balance S Y S T E M S Wing tank A321 A318/A319/A320 Optional additional center tanks for A319/A320 200/A321 2. THE SINGLE-AISLE FAMILY (A318/A319/A320/A321) 2.1. Tanks and capacities Compared with A318/A319/A320, A321 wings have been modified in order to support higher weights. As a consequence, contrary to all the other Airbus aircraft, there is no separation between outer and inner tanks on A321. 2.1.1. A318/A319/A320 Note : One or two optional additional center tanks can be fitted (on the A319 and A320-200 only) Fuel Capacity (Usable fuel) – density: 0.785kg/L Outer Tanks (x 2) Inner Tanks (x 2) Center Tank Total without ACT ACT Total with 1 ACT Total with 2 ACTs Liters 880 6925 8250 23860 2992 26852 29844 Volume US Gal 232 1830 2180 6304 790 7094 7885 Kg 691 5436 6476 18730 2349 21079 23428 Weight Lb 1523 11984 14277 41292 5179 46471 51649 Note: this does not apply to the A320-100, which has no center tank and slightly dissymmetrical inner tanks. Please refer to Weight and Balance Manual for relevant information. B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 41 S Y S T E M S 2.1.2. A319 Corporate Jet The A319 CJ can be fitted with up to six additional center tanks. Due to specific issues raised by this configuration, applicable information will be presented separately from other A319 aircraft. Fuel Capacity (Usable fuel) – density: 0.785kg/L Outer Tanks Inner Tanks Center Tank Total without ACT Liters 880 (x2) 6925 (x2) 8250 23860 Volume US Gal 232 (x2) 1830 (x2) 2180 6304 Kg 691 (x2) 5436 (x2) 6476 18730 Weight Lb 1523 (x2) 11984 (x2) 14277 41292 ACT 1 ACT 2 ACT 3 ACT 4 ACT 5 ACT 6 Total with 6 ACTs Liters 3104 2180 2180 3036 3104 3104 40568 Volume US Gal 820 576 576 802 820 820 10718 Kg 2437 1711 1711 2383 2437 2437 31846 Weight Lb 5372 3773 3773 5254 5372 5372 70207 Note: Two fuel operating sequences are available on A319 CJ. ACTs are fueled in the following order : • Seq A: 1, 2, 3, 4, 5 and 6 • Seq B: 1, 2, 4, 6, 3 and 5 and defueled in the reverse order. Please refer to the Weight and Balance Manual for applicable information. B. FUEL SYSTEMS 42 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2.1.3. A321 Note : One or two optional additional center tanks can be fitted (on A321-200 only) Fuel Capacity (Usable fuel) – density: 0.785kg/L Wing Tanks Center Tank Total without ACT ACT Total with 1 ACT Total with 2 ACTs Liters 7745 8210 23700 2992 26692 29684 Volume US Gal 2046 2169 6261 790 7052 7842 Kg 6080 6445 18605 2349 20954 23302 Weight Lb 13404 14208 41015 5178 46193 51371 B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 43 S Y S T E M S 2.2. Fuel System The standard body family has the simplest fuel systems, as it is neither equipped with a CG control system nor a trim tank. Indeed, the benefits of a CG control system on the much shorter missions of the A320 family aircraft would be negligible compared with the cost related to the installation of a CG control system (maintenance costs and extra weight on board). So, the fuel system only deals with fuel quantities and tank transfer issues. As explained above, some differences can be observed depending on the aircraft type and on the modifications fitted on the aircraft (e.g. ACTs) 2.2.1. Engine feed and fuel transfer On A318, A319 and A320 aircraft, there are six main pumps: two pumps in the center tank (except A320-100 which has no center tank) and two pumps in each inner tank. Each engine is fed with one pump in the center tank and with the two pumps in its own side inner tank. When inner tanks reach low level, valves between outer and inner open and an automatic gravity transfer occurs. On A321, each engine is supplied from two pumps in its own side wing tank. Fuel transfers from center tank to wing tanks are managed through a transfer valve. When aircraft are equipped with ACTs (Additional Center Tanks), fuel transfer is made by pressurization. ACTs are emptied one by one into the center tank. 2.2.2. Control and indication The A320 family aircraft are fitted with a Fuel Quantity Indication (FQI) system and three Fuel Level Sensor Control Units (FLSCU). The FQI provides the crew with information regarding fuel (total fuel mass, quantity and temperature in each tank) via the ECAM and based on data from: − A set of capacitance probes in each tank measuring fuel level and temperature, − One densitometer (cadensicon) sensor in each wing inner tank (in wing tank for A321) to measure density of fuel and, − One CIC (capacitance Index Compensator giving the dielectric constant of the fuel) to give the density in case of cadensicon failure. A318/319/320 ECAM fuel page A321 ECAM fuel page B. FUEL SYSTEMS 44 Getting to Grips with Aircraft Weight and Balance S Y S T E M S The FQI also controls the automatic refueling by determining the target levels in each tank. The FLSCUs include probes and temperature sensors located in the tanks during refueling and transfer to detect low and high fuel levels in tanks. They generate signals that are used to operate the valves during refueling and transfers (from center tank to wing tanks as well as from ACTs to center tank). On A319CJ, which can be fitted with up to 6 ACTs, specific units (AFMC - Auxiliary Fuel Management Computer and ALSCU - Auxiliary Level Sensor Control Unit) are dedicated to ACT fuel management. The following diagram presents the fuel system architecture: WING TANK PROBES & SENSORS REFUEL CONTROL PANEL FQI COMPUTER WING TANK PROBES & SENSORS REFUEL VALVES FLSCU (FUEL LEVEL SENSOR CONTROL UNIT) ADIRS ECAM UPPER DISPLAY ECAM FUEL DISPLAY FMGS FLIGHT CREW B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 45 S Y S T E M S 2.3. CG travel during refueling 2.3.1. A318/A319/A320 The refueling sequence and the resulting fuel vector are the same for A318, A319 and A320 aircraft: 1 Outer tanks (full). If an inner tank contains less than 750 kg of fuel, valves between the outer and inner tanks open and fuel spills from the outer to the inner tanks (2). 3 Inner tanks (full) 4 Center tank (full) 5 ACT1 then ACT 2 (if applicable) The graphs below illustrate examples of the fuel vector impact on the certified CG envelopes: 35 40 45 50 55 60 65 70 75 80 10 30 50 70 90 110 Index W e i g h t ( t o n n e s ) 35 40 45 50 55 60 65 70 75 80 10 30 50 70 90 110 Index W e i g h t ( t o n n e s ) A318 A319 (no ACT) 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 -15 -5 5 Delta Index F u e l W e i g h t ( k g ) 5 4 3 1 2 B. FUEL SYSTEMS 46 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 35 40 45 50 55 60 65 70 75 80 10 30 50 70 90 110 Index W e i g h t ( t o n n e s ) 35 40 45 50 55 60 65 70 75 80 10 30 50 70 90 110 Index W e i g h t ( t o n n e s ) A319 CJ (with 6 ACTs – Seq B) A320 (with 2 ACTs) Note: On A319CJ, due to the range of the fuel vector, specific ZF envelopes have been certified in order to ensure that CG is kept inside the limits in case of failure of the fuel transfer function from the ACTs to the center tanks. B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 47 S Y S T E M S 45 50 55 60 65 70 75 80 85 90 95 0 10 20 30 40 50 60 70 80 90 100 110 Index W e i g h t ( t o n n e s ) 2.3.2. A321 The refueling sequence for the A321 and the resulting fuel vector are the following: 1 Wing tanks (full) 2 Center tank (full) 3 ACTs (if applicable) The following chart presents the impact of the refueling vector on the certified CG envelopes. 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 -15 -10 -5 0 5 10 15 Delta Index F u e l W e i g h t ( k g ) 3 2 1 B. FUEL SYSTEMS 48 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2.4. In-flight CG travel 2.4.1. A318/A319/A320 The fuel burn sequence for the A318, A319, A320 is as follows: 1/ ACTs (ACT2 then ACT1) – fuel transferred into the center tank (if applicable) 2/ center tank (until empty) 3/ inner tanks (until 750kg left in each tank) 4/ outer tanks – all the fuel transferred to the inner tanks from where it is fed to the engines 5/ inner tanks (until empty) The only transfer that takes place is the transfer of fuel from the outer to the inner tanks when the fuel quantity in the inner tanks reaches a low level of 750kg. The valves between the outer tanks and the inner tanks open and are latched open until the next refueling. This does not necessarily occur simultaneously in both wings. This transfer brings the CG forward. As a consequence, the fuel vector for defueling is the same as for the refueling. 2.4.2. A321 On A321, only the wing tanks are fitted with engine feed pumps. All the fuel located in the center and auxiliary tanks have to be pumped into the wing tanks in order to be burnt. The fuel burn sequence is therefore the following: 1/ ACTs (ACT2 then ACT1) – fuel transferred to the center tank (if applicable) 2/ center tank – fuel transferred to the wing tanks 3/ wing tanks So, the fuel vector is the same for refueling and defueling. B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 49 S Y S T E M S 3. THE LONG-RANGE FAMILY (A330/A340) 3.1. Tanks and capacities 3.1.1. A330-200/-300 As far as fuel is concerned, the main difference between the models is that the A330-200 is fitted with a center tank in order to cover longer-range missions than the A330-300 The following table gives the detail of fuel tanks capacity on the A330. Fuel Capacity (Usable fuel) – density: 0.785kg/L Outer Tanks (x2) Inner Tanks (x2) Trim Tank Total A330-300 Center Tank Total A330-200 Liters 3650 42000 6230 97530 41560 139090 Volume US Gal 964 11096 1646 25767 10980 36748 Kg 2865 32970 4890 76560 32625 109185 Weight Lb 6316 72686 10780 168784 71925 240709 Note: These values are applicable to for all A330-200 and for A330-300 from MSN 256 and above. For relevant information, please refer to the Weight and Balance Manual or to the Aircraft Flight Manual. A330-200 only B. FUEL SYSTEMS 50 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 3.1.2. A340-200/-300 Note: One optional additional center tank can be fitted. Fuel Capacity (Usable fuel) – density: 0.785kg/L Outer Tanks (x2) Inner Tanks (x2) Trim Tank Center Tank Total Liters 3650 42775 6230 42420 141500 Volume US Gal 964 11301 1646 11207 37384 Kg 2865 33578 4890 33300 111076 Weight Lb 6316 74026 10780 73413 244878 ACT Total with ACT Liters 7200 148700 Volume US Gal 1902 39287 Kg 5652 116728 Weight Lb 12460 257339 Note: These values apply for all aircraft from MSN 179 and above and to some previous MSNs. For relevant information, please refer to the Weight and Balance Manual or to the Aircraft Flight Manual. B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 51 S Y S T E M S 3.1.3. A340-500/-600 Compared with A340-200/-300, A340-500/-600 inner tanks have been split into two inner tanks per wing, mainly for engine burst considerations. Moreover, an extra tank (rear center tank) has been installed on A340-500 Fuel Capacity (Usable fuel) – density: 0.785kg/L Outer Tanks (x2) Inner Tanks 1 & 4 (each) Inner Tanks 2 & 3 (each) Center Tank Trim Tank Total A340- 600 Rear Center Tank Total A340- 500 Liters 6310 24716 34805 55133 7986 194781 19873 214654 Volume US Gal 1667 6530 9195 14566 2110 51461 5250 56712 Kg 4953 19402 27322 43279 6269 152903 15600 168503 Weight Lb 10920 42774 60234 95413 13821 337088 34392 371480 Note: Some aircraft modifications may affect the tanks capacity on A340-500/-600. Particularly, two RCT sizes are available on A340-500 (5 or 7 frame). The information presented in this brochure is applicable to 5-frame RCT. Please refer to Weight and Balance Manual or to the Aircraft Flight Manual for relevant information. A340-500 only B. FUEL SYSTEMS 52 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 3.2. Fuel systems All the aircraft of the long-range family basically follow the same guidelines in terms of fuel system. The main differences between the models mainly result from the number of engines and from the tanks that actually equip the aircraft. In order to take advantage of the large amount of fuel on board and of the possible influence that this fuel position may have on the aircraft CG position, A330/A340 aircraft are fitted with a CG control system involving trim tank transfers that enables to keep the CG as aft as possible during the flight to optimize the fuel consumption. 3.2.1. Engine feed A dedicated collector cell located in the inner wing tanks feeds each engine: − On A330, there is one collector cell per inner tank. Each cell includes two main fuel pumps. One standby pump is installed in the inner tank outside the collector cell. − On A340-200/-300, two collectors cells are located in each inner tank. On A340- 500/-600, there is one collector cell in each of the four inner tanks. For all A340s, each collector cell consists in one main fuel pump and one standby fuel pump. Each collector cell contains about 1000 kg and is maintained full in order to protect the engine feed. A cross feed valve is associated with each engine. When the cross feed valves are open, any pump is able to supply any engine. 3.2.2. Fuel transfers This paragraph aims at briefly describing how the various fuel transfers are performed during the flight. The collector cells located in the inner tanks ensure the engine feed. That implies that the fuel from the other tanks has to be transferred in the inner tanks: − Two pumps enable the transfer from center tank (when applicable). They run continuously as long as there is fuel in the center tank. − Fuel transfer from outer tanks is done by gravity and controlled by transfer valves. For ACT (when fitted) and for RCT on A340-500, the fuel is transferred to the center tank by pressurization. The CG control system generates trim tank transfers during the flight: − Forward transfers: Some aircraft are equipped with one trim tank forward transfer pump for the fuel transfers from trim tank to the inner tanks or to the center tank. In case of the pump failure or if the aircraft is not fitted with it, these transfers are done by gravity. A340-500/-600 aircraft are basically fitted with two forward transfer pumps. − Aft transfers: Fuel is provided from the center tank through the two center tank pumps mentioned above The fuel from inner tank is transferred using the two engine feed pumps On A340-500/-600 aircraft, transfers to trim tank are performed via six dedicated aft transfer pumps (two in the center tank and one per inner tank). B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 53 S Y S T E M S 3.2.3. Control and indication On long range family aircraft, the fuel system (FCMS : Fuel Control and Monitoring System) is controlled by two Fuel Control and Monitoring Computers (FCMCs). Their main functions are: − Fuel transfer control − Aircraft gross weight and CG position calculation − Center of gravity control − Refuel control − Fuel quantity measurement and indication on ECAM and on refuel control panel. A340-200/-300 ECAM fuel page A340-500 ECAM fuel page In normal operation, one FCMC is active while the other is in stand-by. Fuel quantity calculation performed by FCMC is based on the following information: − Fuel volume from tank probes − Fuel density from densitometers − Horizontal stabilizer angle − Aircraft attitude − Fuel electrical characteristics from compensators On A340-500/-600, the tank data (volume, density, electrical characteristics and temperature) is provided to the FCMCs via two Fuel Data Concentrators (FDC). Fuel level sensors also provide the FCMC with information used to control transfers and to trigger warnings independently of the fuel quantity indication. B. FUEL SYSTEMS 54 Getting to Grips with Aircraft Weight and Balance S Y S T E M S The following diagram presents the fuel system architecture: FCMC FCMC 2 Functions ! Quantity indication ! Refuel control ! Transfer/cross feed control ! Center of Gravity Calculations, indication and control ! Level sensing ! Temperature indication ! Warnings ! Stop jettison operation Functions ! Quantity indication ! Refuel control ! Transfer/cross feed control ! Center of Gravity Calculations, indication and control ! Level sensing ! Temperature indication ! Warnings ! Stop jettison operation FCMC FCMC ! Valves ! Pumps ! Pressure switches ! Temperature sensors ! Level sensors (thermistors) ! Fuel quantity sensors, densitometers and compensator ! Valves ! Pumps ! Pressure switches ! Temperature sensors ! Level sensors (thermistors) ! Fuel quantity sensors, densitometers and compensator ECAM ECAM Cockpit overhead panel Cockpit overhead panel ACMS DMU ACMS DMU Refuel panel Refuel panel Fuel system Fuel system 1 FWC FWC FWC FWC ECAM ECAM FMGEC FMGEC AFT CG warning Gross weight AFT CG target/caution ZFW and ZFWCG TTD MCDU ADIRS ADIRS ADIRS ADIRS ADIRS ADIRS FADEC FADEC FCDC FCDC FCDC FCDC A/C attitude Recirculation THS position LGCIU LGCIU LGCIU LGCIU SFCC SFCC SFCC SFCC APU APU WBC WBC CMC CMC CMC CMC ACARS BLOCK FUEL, ZFW, ZFWCG Maintenance data (bite) Option Gross weight/CG Fuel system isolation Slats extended LDG gear up/down flight/ground FCMC INTERFACE WITH AIRCRAFT SYSTEMS B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 55 S Y S T E M S 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 110000 120000 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 Delta Index F u e l W e i g h t ( k g ) 2 3 4 5 6 7 8 1 3.3. CG travel during refueling During automatic refueling, once a fuel quantity has been selected, all the tanks are filled simultaneously according to a given fuel distribution. The following graph is published in FCOM 2.01.30 and enables to determine the fuel distribution in each tank at the end of refueling as a function of the total fuel quantity: Refueling distribution A340-300 FCMS 7.0 FCMS modifications have been introduced in order to optimize the fuel sequences by reducing the fuel vector range. The following information is based on FCMS 9.0 (10.0), which is the production standard at the date of the publication, and on the fuel tank capacities mentioned above. Please refer to the Weight and Balance Manual for applicable information. 3.3.1. A330-200-300 and A340-200/-300 The refueling sequence for A330 and A340-200/-300 is as follows: 1 inner tanks up to 4500 kg per side (to fill in the collector cells) 2 outer tanks (full) 3 inner tanks up to total fuel equals 36500 kg 4 trim tank up to 2400 kg 5 inner tank (full) 6 A330-200, A340: simultaneously trim tank (full) and center tank (full) 7 A340: ACT (if applicable) 8 A330-300: trim tank (full) B. FUEL SYSTEMS 56 Getting to Grips with Aircraft Weight and Balance S Y S T E M S The graphs below illustrates the fuel vector impact on the certified CG envelopes: 100 120 140 160 180 200 220 240 50 70 90 110 130 150 170 190 Index W e i g h t ( t o n n e s ) 100 120 140 160 180 200 220 240 20 40 60 80 100 120 140 160 180 200 Index W e i g h t ( t o n n e s ) A330-200 A330-300 120 140 160 180 200 220 240 260 280 40 60 80 100 120 140 160 180 200 Index W e i g h t ( t o n n e s ) A340-200/-300 (1 ACT) B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 57 S Y S T E M S 3.3.2. A340-500/-600 A340-500 and A340-600 have similar refueling sequences: 1 Inner tanks 1,2,3 and 4 up to up to 3000 kg per tank, Total fuel = 12000 kg (to fill in the collector cells) 2 Outer tanks up to up to 4500 kg per tank, Total fuel = 21000 kg 3 Inner tanks 1, 2, 3 and 4 up to up to 18200 kg per tank, Total fuel = 81800 kg 4 Inner tanks 2 and 3 up to 25700 kg per tank, center tank up to 17000 kg and trim tank up to 2400 kg, Total fuel = 116200 kg 5 Center tank up to 40000 kg and trim tank up to 5900 kg, Total fuel = 142700 kg 6 A340-500: rear center tank up to 14956 kg, Total fuel = 157656 kg 7 Inner tanks 1, 2, 3 and 4 (full), outer tanks (full), center tank (full), trim tank (full) and for A340-500: rear center tank (full) This sequence leads to the following refueling vectors: 0 20000 40000 60000 80000 100000 120000 140000 160000 -10 -5 0 5 10 15 20 Delta Index F u e l W e i g h t ( k g ) 0 20000 40000 60000 80000 100000 120000 140000 160000 -5 0 5 10 Delta Index F u e l W e i g h t ( k g ) A340-500 A340-600 1 2 3 4 5 6 7 1 2 3 4 5 7 B. FUEL SYSTEMS 58 Getting to Grips with Aircraft Weight and Balance S Y S T E M S The following graphs give an example of the fuel vector impact on the certified CG envelope. 160 210 260 310 360 40 60 80 100 120 140 160 180 200 Index W e i g h t ( t o n n e s ) A340-500 160 210 260 310 360 20 40 60 80 100 120 140 160 180 200 Index W e i g h t ( t o n n e s ) A340-600 B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 59 S Y S T E M S 3.4. In-flight CG travel 3.4.1. Fuel burn CG travel This paragraph deals with in-flight CG travel due to depletion with no consideration of CG control, which is detailed in the next paragraph. As described previously, engines are only fed from the inner tanks and so, all the fuel from the other tanks have to be transferred to the inner in order to be burnt. Besides, the fuel burn sequence for long-range family aircraft and the associated fuel transfers are in accordance with the basic structural constraints (wing root stress). As for refueling data, the following depletion sequence is applicable to FCMS 9.0 standard : a) A330-200/-300 and A340-200/-300 − 1/ ACT (if applicable) fuel transferred to the center tank − 2/ Center tank (if applicable) fuel transferred to the inner tanks − 3/ Inner tanks down to a given level (ie 4000 or 5000 kg in each inner tank depending on the aircraft) − 4/ Trim tank fuel transferred to the inner tanks − 5/ Inner tanks is emptied down to a second given level (ie 3500 or 4000 kg in each inner tank) − 6/ Outer tanks fuel transferred in the inner tanks − 7/ Inner tanks (until empty) b) A340-500/A340-600 − 1/ Center tank fuel transferred to all inner tanks until center tank fuel quantity reaches 17000 kg − 2/ Center tank fuel transferred to inner tanks 1 and 4, to maintain full quantity, until all inner tanks are balanced (approximately 18000 kg per inner tank) − 3/ Rear center tank (if applicable) fuel transferred to the center tank when the center tank quantity reaches 1000 kg − 4/ Center tank fuel transferred to all inner tanks, cycling the inner tanks quantities between 17200 and 18200 kg, until the center tank is empty − 5/ Inner tanks down to 4000 kg per inner − 6/ Trim tank fuel transferred to the inner tanks − 7/ Inner tanks is emptied down to 2000 kg per inner − 8/ Outer tanks fuel transferred in the inner tanks − 9/ Inner tanks (until empty) All the transfers mentioned here are managed automatically by the fuel system. The fuel burn sequence is a reference vector, which is not strictly followed in flight as the CG position is modified by the CG control system. B. FUEL SYSTEMS 60 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 3.4.2. CG control system The position of the aircraft CG during the flight has an impact on the fuel consumption. Indeed, an aft CG position reduces the drag and then implies fuel savings. That is the reason why a CG control system has been introduced on long-range family aircraft. a) CG target In flight, the FCMC controls the position of the center of gravity. It calculates the CG position and compares it to a target value, which depends on the aircraft weight. According to this calculated CG position compared to the target, the FCMC determines the fuel quantity that needs to be transferred aft or forward. The graph below is published in FCOM 1.28.10 and provides with the target CG expressed in %MAC as a function of the aircraft weight: AFT CG Target - A340-300 The FCMC determines the fuel quantities to be transferred to maintain the aircraft CG in a control band limited by the CG target position and CG target position – 0.5%. Considering a typical CG envelope layout, the control band can be presented as follows: Aircraft Weight MTOW ZFW CG control band Certified CG envelope B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 61 S Y S T E M S b) CG control The following profile describes the CG control system behavior throughout the flight: The CG control function is active once the aircraft has reached FL 255. It is deactivated when the aircraft flies below FL 245 or when time-to-destination from the FMGS is less than a given value, which depends on the aircraft type and on whether a trim tank pump is fitted and operative. CG control starts with an aft transfer to the trim tank when all the following conditions are met: − The landing gear is up and the slats are retracted − The trim tank is not full − The aircraft CG is not on the target − Each inner tank quantity is above 6250kg (6000 kg for A340-500/-600) − The Flight Level is above FL 255 Normally only one aft transfer is generated during the flight. However, it can happen that an additional aft transfer occurs when both the CG position is 2% forward the target value and the trim tank reaches a low level. An aft transfer ends if one of these conditions is fulfilled: − The computed CG reaches Target CG - 0.5% − The trim tank is full − The inner tank quantity reaches 6250kg (4000 kg for A340-500/-600) − The crew requests a manual fuel transfer (forward trim transfer or transfer from the center or outer tanks to the inner tanks). − Jettison is selected B. FUEL SYSTEMS 62 Getting to Grips with Aircraft Weight and Balance S Y S T E M S Then, during the normal fuel burn, center tank and inner tanks depletion brings the CG further aft. Automatic forward transfers from the trim tank (and also from the RCT on A340-500) keep the CG position within the CG control band. These transfers occur in each of the following circumstances: − The Calculated CG position reaches the target CG. The transfer stops when the calculated CG reaches CG Target -0.5% − The fuel quantity in one of the inner tanks decreases down to 4000 kg (or 5000 kg depending on the aircraft). The transfer stops when the level reaches 5000 kg (or respectively 6000 kg). − The FMGS sends a time-to-destination signal or the aircraft is in descent below FL245. In this case, the fuel transfer is continuous and stops only if the inner tanks are overflowing. These transfers take into account potential tank imbalance that can be encountered during the flight. In case the inners are unbalanced by more than 500 kg, either forward transfer is directed to the lightest tank or aft transfer is stopped on the lightest tank. c) CG target possible shifts during flight During the flight all the fuel transfers are based on the CG position determined by the FCMC, these positions are linked to the ZFW and ZFCG values input by the pilot before flight in the MCDU. An independent CG determination is made by the FMGC. If the CG position computed by the FMGC is too far aft, the target CG position in the FCMC is automatically shifted forward (by 1.5% or 2%). If the resulting corrections are not enough to avoid the CG position to excess the FE limit, an aft CG warning is triggered that requires a manual forward transfer. In order to protect the aft CG limitation, the target also moves forward by 1.5% in case of FQI data degradation or if ZFCG/ZFW have not been entered or need to be reinitialized. B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 63 S Y S T E M S d) Example of CG control operation Automatic fuel transfers that actually happen during the flight depend on the initial amount of fuel in the tanks and on the aircraft Zero Fuel CG position. The following table presents the different cases that can be encountered according to the initial conditions (CG position and fuel quantity): Refuel vector Depletion vector CG control band (Metric tonnes) Control band reached Control band not reached A340-300 max full ~ 116.7 t MTOW Collectors Trim Inner wings Outer wings Trim and center ACT Center depletion Inner depletion C G c o n t r o l Trim fwd transfer MTOW Center + ACT depletion Inner depletion Trim fwd transfer A340-300 wings full ~ 75.3 t MTOW Trim fwd transfer Trim aft transfer C G c o n t r o l MTOW Trim fwd transfer Trim aft transfer Inner depletion A340 wings half full ~ 60 t MTOW Trim fwd transfer Trim aft transfer C G c o n t r o l MTOW Trim fwd transfer Trim aft transfer Inner depletion B. FUEL SYSTEMS 64 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 4. THE WIDE-BODY FAMILY (A300-600/A310) 4.1. Tanks and capacities Note : One or 2 ACTs can be installed on A300-600 and A310-300. Please refer to the Weight and Balance Manual for applicable information. Fuel Capacity (Usable fuel) – density: 0.782kg/L A300-600 A300-600R Outer Tanks (x2) Inner Tanks (x2) Center Tank Total A300- 600 Trim Tank Total A300 -600R ACT Total A300 -600 1 ACT Total A300 -600 2 ACTs Liters 4630 17570 17600 62000 6150 68150 7000 69000 76000 Volume US Gal 1223 4642 4650 16380 1625 18005 1849 18230 20079 Kg 3621 13740 13763 48483 4809 53292 5474 53957 59431 Weight Lb 7982 30290 30342 106886 10602 117488 12068 118954 131022 Fuel Capacity (Usable fuel) – density: 0.785kg/L A310-200 A310-300 Outer Tanks (x2) Inner Tanks (x2) Center Tank Total A310 -200 Trim Tank Total A310 -300 ACT Total A310 -300 1 ACT Total A310 -300 2 ACTs Liters 3700 13950 19640 54940 6150 61090 7200 68290 75490 Volume US Gal 978 3686 5189 14515 1625 16140 1902 18042 19944 Kg 2905 10951 15417 43128 4828 47956 5652 53602 59260 Weight Lb 6403 24143 33988 95080 10644 105724 12460 118184 130644 B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 65 S Y S T E M S 4.2. Fuel Systems 4.2.1. Engine feed and fuel transfers Each of the five main fuel tanks (inner, outer and center tank) is equipped with two fuel pumps. Engines are fed: − From the center tank when the aircraft is on ground and in flight when slats are retracted. The pumps supply both engines simultaneously. − From inner tanks at takeoff, with slats extended and when the center tank is empty. − From the outer tanks when the inner and center tanks are empty. The pumps in the outer tanks are kept on throughout the flight. When the aircraft is equipped with ACT(s), the fuel is transferred in the center tank by pressurization. ACT fuel transfer pump is used on ground and in case of the pressurization system failure. This transfer is inhibited during trim forward transfer to the center tank. The tail trim tank (when applicable) is fitted with two transfer pumps for aft transfers generated by the CG control system. 4.2.2. Control and indication The FQI (Fuel Quantity Indicating) computer provides the crew with fuel quantity information by processing data from: − A fuel specific gravity sensor (Cadensicon) − An attitude sensor which provides with aircraft pitch attitude and bank angle − A compensator probe in each tank for the fuel dielectric characteristics The resulting fuel quantity is displayed on the ECAM fuel page, on the fuel quantity indicator on the overhead panel and on the external fuel panel. The FQI uses this information to monitor the refueling by closing the refuel valves when the preset quantities are reached. The Fuel Autofeed System controls the inner tanks and center tank pumps according to the normal fuel feed sequence. The Autofeed system is activated when at least one pump pushbutton is switched in NORMAL position for each inner tank and for the center tank. The outer tank pumps are not managed by the Autofeed system. They run continuously during the flight. Contrary to the long-range family, the center of gravity control system is independent of the fuel feed and the refueling system. The CGCC (Center of Gravity Control Computer) controls the transfers from and to the trim tank. B. FUEL SYSTEMS 66 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 4.3. CG Travel during refueling Tanks are refueled in the following order: 1 Outer tanks 2 Inner tanks 3 Center tank 4 A300-600 and A310-300: ACT 1 (if applicable) 5 A300-600R and A310-300 : Trim tank 6 A300-600 and A310-300: ACT 2 (if applicable) Refueling vector Refueling vector A300-600R A310-300 with 2ACTs The graphs below give an example of the fuel vector impact on the certified CG envelope: 90 100 110 120 130 140 150 160 170 0 10 20 30 40 50 60 70 80 90 100 110 Index W e i g h t ( t o n n e s ) 90 100 110 120 130 140 150 160 10 20 30 40 50 60 70 80 90 100 110 120 Index W e i g h t ( t o n n e s ) A300-600 (no ACT) A310-300 (1 ACT) 0 10000 20000 30000 40000 50000 60000 -20 -10 0 10 20 30 40 50 60 Delta Index F u e l W e i g h t ( k g ) 0 10000 20000 30000 40000 50000 60000 -20 -10 0 10 20 30 40 50 60 Delta Index F u e l W e i g h t ( k g ) 1 2 3 4 5 6 1 2 3 5 B. FUEL SYSTEMS Getting to Grips with Aircraft Weight and Balance 67 S Y S T E M S 4.4. In-flight CG travel The normal fuel burn with no consideration of the CG control system is as follows: − 1/ ACT 2 then ACT 1 (when applicable) fuel transferred in the center tank − 2/ Center tank − 3/ Inner tanks − 4/ Trim tank fuel transferred progressively in the center tank until the trim tank is empty − 5/ Center tank − 6/ Outer tanks As explained previously, the Autofeed system controls the fuel feed sequence. Automatic fuel transfer from ACT to the center tank occurs when center tank high level has been dry for ten minutes. It stops when the center tank high level is rewetted. Once the inner tanks are empty, the CGCC generates a forward fuel transfer from the trim tank to the center tank. The normal depletion vector is a reference that is not actually fulfilled as the CG position is impacted by the CG control system. 4.5. CG control system Only A300-600R and A310-300 are equipped with a trim tank and an associated CG control system. Center of Gravity control and monitoring is achieved by the CGCC (Center of Gravity Control Computer). The CGCC has three main functions: − To compute the aircraft CG and gross weight based on the ZFCG and ZFW (entered by the crew in the CDU), the fuel quantity in each tank and the aircraft pitch angle. − To monitor the CG and maintain a CG target − To order fuel transfers in order to maintain the CG target. As for long-range aircraft, the CG target is defined as a function of the aircraft weight. It also depends on the flight level. The following graph is published in FCOM. CG target A310-300 During takeoff and landing, the trim tank is isolated. The trim tank isolation valve opens at takeoff when the slats are retracted and closes at landing when the gear is down. B. FUEL SYSTEMS 68 Getting to Grips with Aircraft Weight and Balance S Y S T E M S CG control is activated above FL 205. In climb below FL 205, forward transfers can be initiated if the aircraft reaches its aft CG target. However, no aft transfer is permitted. Above FL205, the CGCC initiates fuel transfers in order to maintain the CG within 0.5% forward of the CG target. As for the long-range family, this starts with an aft fuel transfer (normally only one per flight) and continues with forward fuel transfers to compensate for the fuel burn. If the inner tanks are empty, the CGCC transfers fuel from trim tank into the center tank in order to maintain fuel quantity in the center tank (500 to 1000 kg). This is done without any regards to the CG target. The fuel used in aft transfers comes from the center tank or from the inner tanks if the center tank is empty. Forward transfers bring fuel from the trim tank to the center tank. No fuel can be transferred from the trim tank to the inner tanks. In descent below FL 200, the CGCC orders a fast forward fuel transfer from the trim tank to the center tank. This stops when one of the following conditions is met: − the trim tank is empty − the center tank is full − the CG has reached the forward CG limit. In order to protect the aft CG limit, an independent CG monitoring is performed by the FWC (Flight Warning Computer) based on THS position data. In case the CG is found too far aft, an ECAM warning is triggered and the CG target is shifted forward. The CG target is also moved forward in case of a manual forward transfer (for more than 10 seconds) and when FQI data accuracy is degraded. C. LPC WEIGHT AND BALANCE SYSTEM Getting to Grips with Aircraft Weight and Balance 69 S Y S T E M S C. LESS PAPER IN THE COCKPIT WEIGHT AND BALANCE SYSTEM 1. GENERALITIES The Less Paper in the Cockpit – Weight & Balance module is an interface designed for the pilot for use in the cockpit to compute the different weights and center of gravity (CG) positions of the aircraft and to check them against their operational limitations. The interface runs on a laptop equipped with Windows operating system. The Less paper cockpit package is a more comprehensive package comprising of document consultation (FCOM and/or MEL) and of performance computation (Takeoff, Landing, Weight & Balance, Flight). Each module may be present or not depending on the operator’s choice. The user interface of the Less Paper in the Cockpit – Weight & Balance module (termed as LPCWBU in the following) uses the data exclusively defined by the administrator. Indeed, the LPCWB package is delivered as an empty shell and the administrator has to feed the LPCWB environment with the fleet’s weight and balance data (aircraft main characteristics, fuel tanks data…) as well as the operational data (influence of passengers and cargo loading on the CG - operational envelopes). The administrator defines also the general layout and operations of the user interface as this latter is very flexible and can be adapted to the airline's type of operations. To complete these tasks, the administrator uses the dedicated functions of the administrator interface namely LPCA and in addition can optionally use comprehensive data files produced the LTS software. With the LPCWBU interface, pilots define the configuration of the flight, load the aircraft with passengers, cargo and fuel and distribute the payload in the cabin and in the holds. Various checks are performed throughout the data entry process and at the end, pilot gets results graphically and numerically. 70 Getting to Grips with Aircraft Weight and Balance S Y S T E M S 2. USER INTERFACE – GENERAL PRESENTATION The interface is composed of the following frames: Aircraft frame: Displays information regarding aircraft selection made on welcome page (given for information only). − 1 and 2 Departure frame (Shortcut <F2>): Allows selecting the departure airport. − 3 Configuration frame (Shortcut <F3>): Allows defining the aircraft configuration before loading payload and fuel. − 4 Loading frame (Shortcut <F4>): Enables to load the aircraft. This frame fulfils all the tasks of a conventional load sheet. − 5 Inop Item (Shortcut <F5>) This function is not available at this version. − 6 Payload distribution (Shortcut <F6>) and Fuel distribution (Shortcut <F7>): Enables to visualize or define passenger, cargo and fuel distribution − 7 Results frame: Presentation of results (numerically and graphically). 1 3 4 5 7 6 2 Getting to Grips with Aircraft Weight and Balance 71 W E I G H T A N D B A L A N C E E N G I N E E R I N G WEIGHT AND BALANCE ENGINEERING A. Generalities.............................................................................. 75 1. Definitions........................................................................................................................... 75 1.1. Center of Gravity (CG) ................................................................................................. 75 1.2. Mean Aerodynamic Chord (MAC) ................................................................................ 75 2. Forces applied on flying aircraft .......................................................................................... 76 3. Influence of the CG position on performance...................................................................... 77 3.1. Impact on the stall speed ............................................................................................. 77 3.2. Impact on takeoff performance..................................................................................... 79 3.3. Impact on in-flight performance.................................................................................... 84 3.4. Impact on landing performance.................................................................................... 87 3.5. Summary ..................................................................................................................... 88 3.6. Conclusion................................................................................................................... 88 4. Certified limits design process ............................................................................................ 89 4.1. Certification requirements ............................................................................................ 90 4.2. Take-off Limitations...................................................................................................... 91 4.3. Aircraft stability and maneuverability Limitations .......................................................... 93 4.4. Final Approach Limitations........................................................................................... 98 4.5. Landing Limitations ...................................................................................................... 99 4.6. Limitation summary...................................................................................................... 99 4.7. Certified limits definition ............................................................................................. 100 4.8. SUMMARY : CG ENVELOPES.................................................................................. 104 B. Weight and Balance Manual .................................................. 108 1. Section 1 : Weight and balance control............................................................................. 108 1.1. 1.00: GENERAL......................................................................................................... 108 1.2. 1.10: LIMITATIONS.................................................................................................... 109 1.3. 1.20: FUEL................................................................................................................. 111 1.4. 1.30: FLUIDS............................................................................................................. 114 1.5. 1.40: PERSONNEL.................................................................................................... 114 1.6. 1.50: INTERIOR ARRANGEMENT ............................................................................ 115 1.7. 1.60: CARGO............................................................................................................. 115 1.8. 1.80: ACTIONS ON GROUND................................................................................... 117 1.9. 1.90: Examples .......................................................................................................... 117 2. Section 2 : Weight Report................................................................................................. 118 72 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G WEIGHT AND BALANCE ENGINEERING C. Balance Chart Design............................................................ 121 1. Moment and Index definitions........................................................................................... 121 1.1. Moment...................................................................................................................... 121 1.2. Index.......................................................................................................................... 123 2. Index variation calculation (∆Index) .................................................................................. 125 2.1. ∆Index for one item.................................................................................................... 125 2.2. ∆Index for additional crew member ............................................................................ 125 2.3. ∆Index for additional weight on the upper deck .......................................................... 126 2.4. ∆Index for passenger boarding................................................................................... 127 2.5. ∆Index for cargo loading............................................................................................. 128 2.6. ∆Index for fuel loading................................................................................................ 130 3. operational limits determination ........................................................................................ 135 3.1. Calculation principle................................................................................................... 135 3.2. Margins determination method................................................................................... 135 3.3. Inaccuracy on initial data (DOW and DOCG) ............................................................. 138 3.4. Inaccuracy on items loading on board the aircraft (passengers, cargo, fuel) .............. 140 3.5. Inaccuracy due to CG computation method................................................................ 162 3.6. Item movements during flight impacting the aircraft CG position ................................ 167 3.7. Total operational margins determination .................................................................... 175 3.8. Takeoff, Landing, In-Flight operational limits determination........................................ 176 3.9. Zero Fuel limit determination...................................................................................... 178 4. Balance Chart Drawing principle....................................................................................... 181 4.1. ∆index scales or tables for loaded items .................................................................... 182 4.2. Operational limits diagram.......................................................................................... 184 5. The AHM560 .................................................................................................................... 186 5.1. Generalities................................................................................................................ 186 5.2. PART A: COMMUNICATION ADDRESSES............................................................... 186 5.3. PART B: GENERAL INFORMATION......................................................................... 187 5.4. PART C: AIRCRAFT DATA........................................................................................ 187 5.5. PART D: LOAD PLANNING DATA............................................................................. 189 D. Load and Trim Sheet software .............................................. 191 1. Introduction....................................................................................................................... 191 2. Objectives......................................................................................................................... 191 3. Software description......................................................................................................... 192 3.1. Unit system: ............................................................................................................... 192 3.2. Aircraft modifications: ................................................................................................. 192 3.3. Aircraft configurations: ............................................................................................... 193 3.4. Cabin layout: .............................................................................................................. 194 3.5. Operational margins customization ............................................................................ 195 A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 73 W E I G H T A N D B A L A N C E E N G I N E E R I N G GENERALITIES INTRODUCTION The purpose of this section is to present the impact of the aircraft CG position on aircraft performance and the certified limits design process. First it is necessary to define precisely what is the Center of Gravity, the way to express it in relation to the Reference Chord (RC) and to detail the forces applied on the aircraft. A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 75 W E I G H T A N D B A L A N C E E N G I N E E R I N G A. GENERALITIES 1. DEFINITIONS 1.1. Center of Gravity (CG) The Center of Gravity or CG is the point where the aircraft’s weight is applied. The position of the CG has to stay within certain limits to ensure aircraft maneuverability and stability and also the aircraft structure integrity. 1.2. Mean Aerodynamic Chord (MAC) All the limitations and the definitions related to weight and balance aspects use what is called the Mean Aerodynamic Chord (MAC) or the reference chord (RC). For example, the position of the center of gravity (CG) is usually expressed in terms of percentage of MAC. The safe limits for the CG are also expressed in terms of percentage of MAC (the symbol used is %MAC) The MAC is a reference line used in the design of the wing; its position relative to the wing and the fuselage is accurately known. The position and dimensions of this reference line are mentioned in the Weight and Balance Manual (WBM Chapter 1.00.05 page2). - Example of the A330-200 - The important points to notice are: − the position and dimension of the MAC − the position of the point located at 25% of the MAC’s length. This point is the reference when it comes to measuring moments. Conversion from %MAC to H-arm 100 % × | | . | \ | − − − = MAC of Length arm H arm H MAC MAC of Edge Leading CG In the above case, the formula would be: 072700 . 0 3380 . 31 % − − = CG arm H MAC . 100 %MAC MAC of Length arm H arm H MAC of Edge Leading CG × + − = − In the above case, the formula would be: 100 27 . 7 3380 . 31 MAC arm H CG × + = − . In order to facilitate the operator’s work, conversion tables from H-arm to %RC and conversion tables from %RC to H-arm are available in the Weight and Balance Manual in chapter 1.00.06. A. GENERALITIES 76 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 2. FORCES APPLIED ON FLYING AIRCRAFT a) Diagram of forces Let us first consider main forces applied on the aircraft. − The weight, applied on the aircraft CG. − The lift, applied on the center of pressure (CP). − The thrust, due to the engines power. − The drag. Weight Lift Center of Gravity Center of Pressure Thrust Drag b) Influence of the THS (Trimmable Horizontal Stabilizer) As lift and weight are not applied on the same point, a pitch-down moment is generated during the flight. Pitch down moment Lift Center of Gravity Center of Pressure Weight In order to keep the airplane level, a downward force is created by the Trimmable Horizontal Stabilizer (THS) which has to be trimmed accordingly. This additional force creates both lift degradation and important pitch-up moment that counters the pitch-down moment. The pitch up moment is due to important balance arm between the aircraft CG position and the THS where the additional force is applied. Downward force Pitch down moment Weight Lift Center of Gravity Center of Pressure Pitch up moment Counter moment THS Note : for aircraft stability reasons the CP is always located behind the CG. A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 77 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3. INFLUENCE OF THE CG POSITION ON PERFORMANCE The impact of CG position on performance varies depending on the flight phase. All influences are linked to the impact of the CG position on the stall speed. 3.1. Impact on the stall speed The stall speed (Vs) is speed at which the aircraft will stall. At that speed the upward force (mainly lift) is equal to the downward force (mainly weight + THS counter force) applied on the aircraft. The lift is directly related to the aircraft speed: the faster the aircraft flies the greater the lift. CG forward ⇒High pitch down moment ⇒Need for high THS counter moment ⇒lift = weight + THS counter force ⇒Stall speed is high THS CG CP CG aft ⇒Small pitch down moment ⇒Need for small THS counter moment ⇒lift = weight + THS counter force ⇒Stall speed is smaller than for forward CG THS CG CP The more forward the CG position, the greater the stall speed (Vs) value. A. GENERALITIES 78 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Example : A340 (High Gross Weight A340-313 with CFM65-5C4 engines) at take off CONF 1+F, Gear up The following graph gives the stall speed value for different aircraft weights, and for two different CG positions (Most forward CG and CG at 26%MAC). Stall Speed at Take Off (Conf 1+F, Gear UP) 105 110 115 120 125 130 135 140 145 150 170 190 210 230 250 270 Weight (tons) C A S ( k t ) Forward CG 26%MAC This graph confirms the stall speed corresponding to a forward CG position is higher than the stall speed for a CG at 26%MAC. The difference can reach 1.5 kts. Note : For conventional aircraft (A300, A300-600 and A310), the reference stall speed, Vs min , is based on a load factor inferior to 1g. This gives a stall speed that is lower than the stall speed at 1g. All operating speeds are expressed as functions of this speed. For Fly by Wire aircraft (A319, A320, A321, A330 and A340), the airworthiness authorities have reconsidered the definition of stall speed: the stall speed is based on a load factor equal to 1g. It is called Vs 1g . Fly by Wire aircraft have a low-speed protection feature (alpha limit) that the flight crew cannot override. Airworthiness authorities have agreed that a factor of 0.94 represents the relationship between Vs 1g and Vs min : Vs min = 0.94 Vs 1g. A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 79 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.2. Impact on takeoff performance 3.2.1. Optimized takeoff distance or takeoff weight The aircraft operating speeds are referenced to the stalling speed. At takeoff: ) 13 . 1 ( 2 . 1 1 2 g Vs Vs V ≥ Now, the V 2 value directly impacts the takeoff distance (or the takeoff weight). Vs V 2 TOD So for a given TOD: the lower the stall speed (Vs) value, the greater the takeoff weight (TOW). The further aft the CG, the smaller the TOD (the greater the TOW). • Influence on TOD A340 CONF 3, AC OFF, AI OFF, OAT 15°C, Zp 0ft TOW = 250 000 kg Forward CG CG at 26%MAC TOD (m) 3241.5 3164.8 % 42 . 2 7 . 76 = = ∆ m TOD !This example shows that, for a given TOW, the aircraft will need a longer runway if its CG is forward. 3.2.2. Takeoff roll An aft CG position gives the aircraft a nose-up attitude that helps the rotation. On the contrary, a forward CG position leads to a nose-heavy situation and a difficult rotation. Taking into account no other limitation (gear strength, VMU…), The further aft the CG, the better the takeoff roll performances. 3.2.3. Takeoff climb An aft CG position gives the aircraft a nose-up attitude that helps the aircraft climb. On the contrary, a forward CG position leads to a nose-heavy situation and a difficult climb. Taking into account no other limitation (gear strength, VMU…), The further aft the CG, the better the takeoff climb performances. • Influence on Climb Gradient A340 CONF 3, AC OFF, AI OFF, OAT 15°C, Zp 0ft TOW = 250 000 kg Forward CG CG at 26%MAC 2 nd segment gradient 5.569% 5.689% !The aircraft climb is facilitated with an aft CG position. A. GENERALITIES 80 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Influence on TOW A340 CONF 3, AC OFF, AI OFF, OAT 15°C, Zp 0ft The difference in 2 nd segment gradient value may not seem significant. So instead of calculating the difference in gradient for the same take-off weight, it is interesting to determine the maximum take off weight for a given climb performance. A second segment climb gradient of 5% is imposed (i.e. obstacle in take-off path). Forward CG CG at 26%MAC TOW (kg) 256215.2 257581.3 kg TOW 1 . 1366 = ∆ !For a given second segment climb gradient, the allowed TOW is increased when the CG is aft. 3.2.4. Basic and alternate CG positions From the 3 previous paragraphs it can be concluded that : The best takeoff performances correspond to an aft CG position. Now, when determining the aircraft takeoff performance (TOW, TOD), the calculation is always performed at the most forward-certified CG position. Therefore, for aircraft having a naturally aft CG position (tail heavy aircraft), everyday operations might be penalized using this very forward value. The A320 and the A340 usually have a DOW CG of around 30%MAC and their most forward certified CG limit is around 17%MAC. These “tail-heavy” aircraft usually have an aft takeoff CG position. This means that their everyday performance is better than the certified performance for the most forward CG position. So a second CG position forward limit has been certified for these two aircraft. − at 25%MAC for the A320 − at 26%MAC for the A340. All takeoff performances in the certified Airplane Flight Manual are given for both these CG positions. However, to take into account the errors in the determination of the CG position, a margin has to be applied on the calculated takeoff CG. I.e., for an A320, in order to be able to use the performance calculated for a 25% CG, the calculated takeoff CG must be of at least 27%. A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 81 W E I G H T A N D B A L A N C E E N G I N E E R I N G a) A320 A320 Basic CG limits A320 Alternate CG limit Therefore, for the A320, the basic certified CG is the aft CG (25%RC) and the alternate CG is the forward CG. Takeoff charts and performances published in the FCOM are usually established for the basic CG position (25%) - Takeoff chart for an A320-232 - If the CG position is forward to the 27% RC point, and if the operator does not have the take-off charts for a forward position, performance corrections have to be applied. These are given in the FCOM 2.02.10. However, should an A320 be operated with an alternate CG position, it is preferable to establish the takeoff charts for that CG position, as the corrections given in the FCOM are conservative. A. GENERALITIES 82 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G b) A340 A340 Basic and Alternate CG For the A340, the basic CG is the most forward CG and the alternate CG is the aft CG (26%). Take off charts and performances published in the FCOM are established for the basic CG position. No corrections are given in the FCOM because the alternate CG performances are better than the basic CG performances. Therefore, an operator that wishes to benefit from the advantages of the alternate CG must establish the appropriate takeoff charts. Influence on TOW Note : The following figures come from the PEP for Windows Take Off and Landing application. It takes into account all the limiting factors for take-off (runway length, climb…). A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 83 W E I G H T A N D B A L A N C E E N G I N E E R I N G The following graphs show (%) TOW ∆ as a function of the TORA length. 100 (%) × | | . | \ | − = ∆ BasicCG BasicCG G AlternateC TOW TOW TOW TOW represents the difference in term of TOW when using the alternate CG for performance calculation instead of the basic CG. Calculations have been performed for a range of TORA and for different airfield altitude. A340-313 CONF 1+F We can notice that the difference in take off weights is all the more important with short runways and an elevated terrain. For example: OAT 20°C Pressure Altitude (Zp) 0ft Runway length 3000m CG position Basic Alternate Takeoff Weight (kg) 266013.9 264207.8 kg TOW 1 . 1806 = ∆ • Conclusion Therefore, by using the performances calculated for the alternate CG (A340) or for the basic CG (A320), the operator can increase the aircraft takeoff weight, thus the payload or the range of the aircraft. On the other hand, the envelope is narrower, thus leading to more constraints on the loading aspect. A. GENERALITIES 84 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.3. Impact on in-flight performance Let’s revert to the impact of the CG position on the forces applied on the aircraft and to the consequence it has on aircraft performance. Reminder: In order to keep the airplane level, the Trimmable Horizontal Stabilizer (THS) creates a downward force. This additional force creates a pitch-up moment that counters the pitch-down moment due to the aircraft weight but also a drag increase which magnitude depends on the aircraft CG position. a) AFT CG POSITION Weight Lift THS Lift degradation Small balance-arm Drag b) FWD CG POSITION Weight Lift THS Lift degradation Long balance-arm Drag The further forward the CG, the greater the counter moment necessary to keep the flight level. This is due to the increasing balance arm between lift and weight. In the case of a forward CG position, the THS is set to an aircraft nose-up position that creates important lift degradation therefore creating important drag. This drag will lead to an increase in fuel consumption. The further aft the CG, the lower the fuel consumption. A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 85 W E I G H T A N D B A L A N C E E N G I N E E R I N G c) Influence on fuel consumption This part refers to the Airbus “Getting to Grips with Fuel Economy” Brochure. During cruise, on all the wide-body Airbus aircraft, the FCMC (Fuel Control and Management Computer) on the A330 and the A340 or the CGCC (Center of Gravity Control Computer) on the A300-600 and the A310 controls the CG position by transferring fuel in the trim tank. The aircraft therefore flies with an aft CG, thus giving better in-flight performance. However, a failure can prevent the fuel transfer and CG position control. The following graphs show the influence of the CG position on the aircraft specific range depending on the aircraft weight. The data are expressed in Specific Range (SR) variations at cruise mach with a center of gravity of 20% and 35%. The SR with a CG position at 27 % is taken as a reference. For the other aircraft, the curves all have a similar shape as these ones: For the A300-600, A310, A330 and A340 types, the further aft the CG, the more significant the fuel savings. Furthermore, when flying above FL350, at a high weight, the decrease or increase in fuel consumption according to the reference is significant. Thus, loading is very important especially for high weights and for aircraft which have no automatic center of gravity management: we notice that, for high weights and FL above 350, the specific range variation can reach 2%. Contrary to the other aircraft, specific range variations with respect to the CG position are random for the whole A320 family. This is due to a complex interaction of several aerodynamic effects. Whatever the influence of the CG position on specific range, it is negligible The single aisle aircraft are not equipped with in-flight fuel transfer systems, they are not fitted with a trim tank. A. GENERALITIES 86 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G d) Example On a 1000 NM stage length, the increases in fuel consumption when the center of gravity position is 20% with regards to the fuel consumption when the center of gravity position is 35% are summed up in the following table for an aircraft with a high weight and at a high flight level. A300-600/A310 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 290 310 330 350 370 390 Flight Level S R v a r i a t i o n ( % ) 100 110t 120t 130t 140t 150t 100t 110t 120t 130t 150t 140t CG=35% CG=20 % 160t 160t CG reference =27 % A340 -2 -1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6 2 290 310 330 350 370 390 Flight Level S R v a r i a t i o n ( % ) 240 t CG = 37 % CG = 20 % 210 t 200 t 190 t 200 t 210 t 220 t 230 t 240 t 230 t 220 t 190 t CG reference = 27 Aircraft types Fuel increment (Kg)/1000Nm between a 20% CG and a 35% CG A319/A320/A321 Negligible A330 220 A340 380 A310 250 A300-600 230 A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 87 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.4. Impact on landing performance 3.4.1. Landing distance or landing weight The aircraft operating speeds are referenced to the stalling speed. At landing: ) 23 . 1 ( 3 . 1 1g App Vs Vs V ≥ Now, the V app value directly impacts the landing distance (or the landing weight). Vs V app LD So for a given Landing Distance: the lower the stall speed (Vs) value, the greater landing weight (LW). Reminder: Forward CG position ⇒ High stall speed Aft CG position ⇒ Low stall speed. The further aft the CG, the smaller the LD (the greater the LW). 3.4.2. Basic and alternate CG positions As for takeoff performances, when determining the aircraft landing performance (LW, LD), the calculation is always performed at the most forward-certified CG position. Therefore, for aircraft having a naturally aft CG position (tail heavy aircraft), everyday operations might be penalized using this very forward value. Only the A320 has two different certified CG. For the other aircraft, the position of the CG is of no influence on landing performances as long as it stays within the certified limits. The important performance as far as landing is concerned is the landing distance. As noted in the FCOM of the A320, a correction has to be made in the case of an alternate CG. A. GENERALITIES 88 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.5. Summary 100 % × | | . | \ | − − − = MAC of Length arm H arm H MAC MAC of Edge Leading CG 100 %MAC MAC of Length arm H arm H MAC of Edge Leading CG × + − = − Stall speed The further aft the CG, the smaller the stall speed (Vs) value. Take off The further aft the CG, the smaller the TOD (the greater the TOW). the better the take off roll performance. the better the take off climb performance. 3.6. Conclusion The best take-off performances will correspond to an aft CG position. In-Flight The further aft the CG, the lower the fuel consumption. Landing The further aft the CG, the smaller the LD (the greater the LW). The further aft the CG, the better the aircraft performance. A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 89 W E I G H T A N D B A L A N C E E N G I N E E R I N G 4. CERTIFIED LIMITS DESIGN PROCESS The previous chapter has dealt with the influence of the position of the aircraft center of gravity on performance. The conclusion was that in general the further aft the CG, the better the aircraft performances. However, the CG has to stay within certain certified limits. These limits are defined in the Limitations volume of the Flight Manual (Chapter 2.02.00) and are also in the Weight and Balance Manual (Chapter 1.10, Limitations) • Example : A320-212 The purpose of this chapter is to explain briefly how these limits are defined and why these limits vary according to the flight phase (take off, landing or in-flight) These limits are mainly due to: − structural limitations − handling qualities − a compromise between performances and aircraft loading A. GENERALITIES 90 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.1. Certification requirements Certain rules have to be respected when designing a CG envelope. The following is an extract from the JAR 25. • J.A.R 25.27: Center of gravity limits The extreme forward and the extreme aft center of gravity limitations must be established for each practicably separable operating condition. No such limits may lie beyond: (a) The extremes selected by the applicant; (b) The extremes within which the structure is proven; or (c) The extremes within which compliance with each applicable flight requirement is shown. • J.A.R 25.143 : General (a) The airplane must be safely controllable and maneuverable during (1) Take-off; (2) Climb; (3) Level flight; (4) Descent; (5) Landing. (b) It must be possible to make a smooth transition from one flight condition to any other flight conditions without exceptional piloting skill, alertness, or strength, and without danger of exceeding the airplane limit-load factor under any probable operating conditions including: (1) The sudden failure of the critical engine. (2) Configuration changes, including deployment or retraction of deceleration devices. In the following chapter all limitations are detailed by flight phase. Take-off run Take-off rotation Climb and Cruise Approach Go-around Landing A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 91 W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.2. Take-off Limitations 4.2.1. Structural limitation a) Main gear Strength: " The further aft the CG is, the heavier the weight over the main gear " The strength of the main gear limits the aft position of the CG for high TOW. Main gear strength : AFT limit (take off) b) Nose gear Strength: " The more the CG is forward, the more the weight over the nose gear " The strength of the nose gear limits the forward position of the CG for high TOW. Nose gear strength : FWD limit (take off) c) Wing strength: The structural limits of the wing will have an effect on the CG limits at high weights. A. GENERALITIES 92 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.2.2. Taxi and Take-off run a) Nose Gear adherence: During taxi and at the beginning of the take-off run, when the speed of the aircraft is not sufficient for the rudder to be effective, the only possible means of controlling the aircraft on the ground is the nose gear steering. In order to be effective, the nose gear wheel must have enough adherence. To have an appropriate adherence, enough weight must be applied on the nose gear. This adherence is further reduced during the take-off run when full power is applied on the engines, thus creating a pitch up moment. (This pitch up moment is due to the engines being located beneath the CG of the aircraft) The further aft the CG, the lesser the adherence. Nose gear adherence : AFT limit (take off) b) Take-off Rotation A forward CG means that the aircraft has a “heavy” nose. This leads to a difficult rotation. The CG position can be moved forward until it reaches the point where rotation becomes impossible. An aft CG means that the aircraft’s nose is relatively “light”. This facilitates the rotation. However, an aft CG limit has to be established in order to prevent a tail-strike during the rotation. Note: A forward CG implies an A/C nose-up trim setting, while an aft CG implies an A/C nose- down trim setting. If the correct trim setting is made prior to take-off, the pilot will always have the same feel during rotation no matter the CG position. However, flight-testing is performed with a forward CG position and an A/C nose-down trim setting (conversely with an aft CG position and an A/C nose-up trim setting) in order to cover the critical condition. Impossible rotation : FWD limit (take off) Tail strike : AFT limit (take off) A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 93 W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.3. Aircraft stability and maneuverability Limitations During all flight phases the aircraft must remain stable and maneuverable. The aircraft CG position has an influence on the aircraft static longitudinal stability in steady flight and during maneuvers. 4.3.1. Static stability Definition: The static stability of an object depends on its tendency to return to its initial position after being slightly moved. Stable Unstable Neutral a) Longitudinal stability during steady flight • Aerodynamic center The increase (or decrease) in lift due to an increase (or decrease) in incidence (α) always applies on a fixed point of the wing. This point is called the aerodynamic center. • Static stability When the aircraft is submitted to a gust, it is equivalent to an increase in incidence or to the creation of a pitch up moment. A lift increase is created at the aerodynamic center. If the CG is located forward of the aerodynamic center, the increase in lift creates a pitch down moment which reduces the incidence and brings the aircraft back to its initial conditions. Pitch down moment due to the lift increase Gust Pitch up moment due to the gust X CG Aerodynamic center X ! The aircraft is stable A. GENERALITIES 94 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G If the CG is located aft to the aerodynamic center, the increase in lift creates a pitch up moment which adds to the initial pitch up moment due to the gust. This brings the aircraft further away from its initial conditions. Gust Pitch up moment due to the gust X Pitch up moment due to the lift increase Aerodynamic center X CG ! !! ! The aircraft is unstable. The CG must not be behind the aerodynamic center. Note : If the center of gravity is located on the aerodynamic center, the lift and the weight have the same application point and there is no moment created the aircraft is neutral Hence the other name for the aerodynamic center: the Neutral Point. Neutral Point : AFT limit (all phases) b) Maneuverability and elevator efficiency Considering the previous paragraph, the more forward the CG, the more stable the aircraft. However, in the case of a very forward CG position, a significant elevator deflection will be necessary to give the aircraft a pitch up attitude. The CG position can be moved forward until it reaches the point where the aircraft is very stable but cannot be maneuvered because the elevator has reached its maximum deflection. In order to be able to fly the aircraft, a compromise has to be reached between stability and maneuverability. The CG is shifted aft until an appropriate maneuverability is found. Note : It is important to notice that the effects of the reduced maneuverability due to a forward CG are emphasized at low speeds when the elevators have a reduced efficiency. The elevator efficiency limit is to be considered for all flight phases and it gives more constraining limit for take-off, approach, and landing than for flight phases. Elevator maximum deflection + Maneuverability margin : FWD limit (all phases) A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 95 W E I G H T A N D B A L A N C E E N G I N E E R I N G c) Longitudinal stability during maneuvers During flight the aircraft must remain stable during steady flight but also during different maneuvers. • Maneuver point The increase (or decrease) in lift due to an increase (or decrease) in load factor (n) applies on a fixed point of the wing. This point is called the maneuver point. This point varies with the type of maneuver (turn, pull-out) and with the aircraft’s weight. It is located behind the aerodynamic center (neutral point). If the CG is located on the maneuver point, the elevator efficiency is infinite. Experience has shown that for stability reasons the CG must be located ahead of the point and at a considerable distance. In order to have an acceptable margin in regards to the maneuver point, a reference point is established for which the maneuverability of the aircraft is reasonable : Point at 1° per g. This point is considered as an aft limit. • Point at 1°per g Example of a turn. R = Turn radius W = Weight = mg Φ ΦΦ Φ = Aircraft bank angle n = Load factor Apparent Weight = n.mg W Φ ΦΦ Φ Lift The load factor during a turn is: n 1 cos = Φ From the previous formula, it appears that the higher the bank angle the higher the load factor. In order to compensate for this higher load factor, the pilot must pull the stick, thus increasing elevator deflection. A. GENERALITIES 96 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G For commercial aircraft the law that gives the elevator deflection (δ) necessary to compensate a given load factor (n) can be represented as follows : Load factor (n) Elevator deflection (δ δδ δ) Given CG position n 1 n 2 δ δδ δ 1 δ δδ δ 2 This law depends on the type of maneuver, aircraft speed, weight and CG position. Drawing this graph for fixed conditions except CG position, gives the following: Load factor (n) Elevator deflection (δ δδ δ) 30% CG n δ δδ δ 30% 40% CG 10% CG δ δδ δ 10% δ δδ δ 40% The further forward the CG position, the greater the necessary elevator deflection to compensate on given load factor. There is a CG position for which 1 degree of elevator deflection compensates a 1 g load factor (for which 1 degree of elevator deflection creates a 1g load factor). This is the 1° per g CG. Load factor (n) Elevator deflection (δ δδ δ) 30% CG n=1g δ δδ δ 40% 40% CG 10% CG δ δδ δ 30% CG 1°per g δ δδ δ=1° The experience has shown that the CG has to be ahead of the 1°/g CG. The position of the 1°/g point depends on the aircraft’s speed. 1°per g point : AFT limit (all phases) A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 97 W E I G H T A N D B A L A N C E E N G I N E E R I N G d) Maximum elevator deflection and extreme load factor Civil aircraft are certified according to the JAR/FAR 25 regulations. These regulations require for maximum acceptable load factor with no structural damage of 2.5g. In order to keep full maneuverability capacity, the maximum elevator deflection must not prevent the pilot from reaching the maximum load factor (pull-out cases for example). This will therefore establish a forward CG limit as shown in the following figure: Load factor (n) Elevator deflection (δ δδ δ) maximum load factor n = 2.5g Maximum elevator deflection δ δδ δ max CG 1 CG 2 CG 3 CG 3 : if aircraft CG is located on CG 3 load factor 2.5g cannot be reached whatever the elevator deflection is. CG 1 : if aircraft CG is located on CG 1 load factor 2.5g can be reached for an elevator deflection lower than δ max . CG 2 : if aircraft CG is located on CG 2 load factor 2.5g is reached for elevator deflection δ max . Aircraft CG cannot be located forward of CG 2 . Maximum elevator deflection (max load factor) : FWD limit (all phases) A. GENERALITIES 98 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.4. Final Approach Limitations 4.4.1. THS stall a) Standard approach During approach, the flaps and slats are extended. This configuration gives the aircraft a pitch- down attitude. This pitch-down moment is countered by an aircraft nose-up THS setting. A forward CG position increases the pitch-down moment and is also countered by an aircraft nose-up THS setting. The combination of the two effects can lead to an important aircraft nose-up THS setting which can eventually lead to a THS stall. b) Approach + push-over When during approach the pilot excessively reduces the speed, in order not to stall and regain a proper approach speed, he will push the stick (“push-over”). In case of a forward CG position countered by an aircraft nose-up THS setting, this procedure may lead to the THS stall because of the aircraft attitude change. THS stall limit : FWD limit (flight and landing) (and take off for final approach in case of emergency landing) 4.4.2. Go Around Setting the engines at full throttle creates a significant pitch-up moment which must be compensated by the elevator. The more aft the CG, the higher the pitch- up moment. The CG position can be moved aft until it reaches the point where the pitch-up moment cannot be compensated anymore by the elevator deflection. Go around : AFT limit (flight and landing) (and take off for final approach in case of emergency landing) 4.4.3. Alpha Floor Protection Alpha floor protection configuration: high angle of attack, low speed and TOGA power. Low speed implies low elevator efficiency. TOGA implies high pitch-up moment. The more the CG is aft, the higher the pitch-up moment. The CG position can be moved aft until it reaches the point where the pitch-up moment cannot be compensated anymore by the elevator deflection. That will limit the aft position of the CG more than the go around limitation. Alpha floor protection : AFT limit (flight and landing) (and take off for final approach in case of emergency landing) A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 99 W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.5. Landing Limitations 4.5.1. Structural limitations Landing structural limitations are similar to take off ones, they are usually less limiting as the aircraft is less heavy then at take off. Main gear strength : AFT limit (landing) Nose gear strength : FWD limit (landing) 4.5.2. Maneuverability and elevator efficiency This limitation concerns all flight phases (ref. B.1.2.3.2) but it is important just before landing, at low speed, when the elevator must enable the pilot to flare out. Thus, elevator maximum deflection and aircraft maneuverability limit the CG position forward. Elevator maximum deflection + Maneuverability margin : FWD limit (landing) 4.6. Limitation summary TAKE OFF FWD AFT Nose gear strength (high weights) Impossible rotation Elevator maximum deflection + maneuverability margin Maximum elevator deflection (max load factor) Main gear strength (high weights) Nose gear adherence Tail strike Neutral Point 1°per g point IN FLIGHT FWD AFT Elevator maximum deflection + maneuverability margin Maximum elevator deflection (max load factor) Neutral Point 1°per g point THS stall limit Go around Alpha floor protection LANDING FWD AFT Nose gear strength Elevator maximum deflection + maneuverability margin Maximum elevator deflection (max load factor) Main gear strength Neutral Point 1°per g point THS stall limit Go around Alpha floor protection A. GENERALITIES 100 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.7. Certified limits definition 4.7.1. Take off limits a) Forward limit The design of the forward limit takes into account the following: − Nose gear strength − Take-off rotation − Maneuverability (efficiency of the elevator when aircraft in-flight) − Flaps/slats extension (final approach in case of emergency landing). Those limitations are classified as handling quality and structural limitations As seen previously (in “Influence of CG Position on Performance”), the FWD CG limit is the reference CG for aircraft performance, as it corresponds to the worst CG position, as far as performances are concerned. ! !! !From the performance point of view the forward limit of the envelope must stay as aft as possible. On the other hand, in order to facilitate the loading of the aircraft, the envelope must be as wide as possible (both aft and forward). If the envelope is too narrow, the operators will have to be very careful on where they locate the freight in the holds and on how they sit their passengers in the cabin. ! !! ! From the loading point of view the forward limit must not be too aft. The retained limit is a compromise between loading and performance. In most of the cases, the handling qualities are ahead of the retained limit. In other words, the envelope could be widened without any impact on handling quality and aircraft safety. However, the handling quality of some “nose heavy” aircraft are already rather limiting. It would penalize the loading to set a more aft limit and in this case, the forward limit corresponds to the handling qualities limitations. For some aircraft and for high TOW the compromise Performance/Loading tends to favour performance more than for low TOW. In aircraft operations the TOCG positions in this area are hardly reached because of loading procedures and fuel vector shape. H a n d l i n g q u a l i t y l i m i t s Limit shift due to the compromise between performance and loading S tr u c tu r a l lim it : N o s e g e a r s tr e n g th C o m p r o m i s e P e r f o r m a n c e / L o a d i n g A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 101 W E I G H T A N D B A L A N C E E N G I N E E R I N G b) Aft limit The design of the aft limit takes into account the following: − Main gear strength − Nose gear adherence − Take-off rotation (Tail strike) − Stability in steady flight and during maneuvers − Go-around and Alpha Floor (final approach in case of emergency landing). Those limitations are classified as handling quality and structural limitations ! !! !From the performance point of view the aft limit of the envelope must stay as aft as possible. ! !! ! From the loading point of view the aft limit must be as aft as possible. For aft CG limits, there is no need for a compromise between loading operations and performance. Only the structural limitations and the handling quality will be taken into account when establishing the aft limit of the CG envelope. S t r u c t u r a l l i m i t : M a i n g e a r s t r e n g t h H a n d l i n g q u a l i t y : L o w s p e e d c o n f i g u r a t i o n ( A l p h a f l o o r o r G o a r o u n d ) H a n d l i n g q u a l i t y : N o s e g e a r a d h e r e n c e A. GENERALITIES 102 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.7.2. Landing limits The limitations that apply for take-off also apply for landing. Nevertheless at landing the aircraft weight is lower than at take off so some limitations are not as restrictive as for take off. In addition the nose wheel adherence does not generate a limitation. a) Forward limit The forward landing envelope is superimposed on the take off one. b) Aft limit The aft landing envelope could usually be set aft of the take off one (less restrictive) . Depending on the aircraft type and on the fuel vector shape it might be useful or not to extend the landing aft limit, so the aft landing envelope is : − either superimposed of the take off one, (fig1) − or set aft of the take off one (fig 2). T a k e - o f f L a n d i n g F l i g h t T a k e - o f f L a n d i n g F l i g h t Fig1 Fig2 A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 103 W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.7.3. In flight limits a) Forward limit The design of the forward limit takes into account the following: − Fuel consumption − Efficiency of the elevator − THS stall b) Aft limit The design of the aft limit takes into account the following: − Point at 1° per g. − Stability in steady flight and during maneuvers − Go-around and Alpha Floor Those limitations are classified as handling quality and structural limitations ! !! !From the performance point of view the forward and aft limit of the envelope must stay as aft as possible to reduce fuel consumption. ! !! ! From the loading point of view the operational limit must be as wide as possible. Usually the in-flight phase is less limiting than the take-off one as limiting factors such as high weights; low speeds and TOGA are specific to take-off phase. During cruise (flight phase), the passenger movements modify the aircraft CG, so during this phase to check the aircraft CG against the in flight envelope those slight CG position modifications must be taken into account. Consequently, the in-flight envelope is chosen with respect to the take-off one. − Opening this envelope as much as possible is useless as the CG is constrained by the T/O phase. − Choosing the in-flight envelope of the same size as the take-off one is too restrictive. Indeed, because of the passenger movements during cruise the in flight envelope becomes more limiting than the take off one. That is why the in-flight envelope is usually deduced from the take-off one and wider from roughly 1 or 2%. Note : the nose gear adherence limitation is not taken into account for the determination of the aft limit. A. GENERALITIES 104 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.8. SUMMARY : CG ENVELOPES 4.8.1. TAKE-OFF Structural limitation: Main gear strength Compromise Performance/Loading Structural limitation: Nose gear strength Handling quality : Alpha floor or Go around Handling quality : Nose gear adherence Maximum structural Take Off Weight 4.8.2. LANDING Maximum structural Take Off Weight Structural limitation: Main gear strength Compromise Performance/Loading Structural limitation: Nose gear strength Handling quality : Alpha floor or Go around Handling quality : Nose gear adherence Maximum structural Landing Weight A. GENERALITIES Getting to Grips with Aircraft Weight and Balance 105 W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.8.3. IN FLIGHT Structural limitation: Main gear strength Compromise Performance/Loading Structural limitation: Nose gear strength Handling quality : Alpha floor or Go around Handling quality : Nose gear adherence Maximum structural Take Off Weight 4.8.4. AIRCRAFT CERTIFIED ENVELOPE B. WEIGHT AND BALANCE MANUAL Getting to Grips with Aircraft Weight and Balance 107 W E I G H T A N D B A L A N C E E N G I N E E R I N G WEIGHT AND BALANCE MANUAL INTRODUCTION The Weight and Balance Manual is the reference as far as weight, balance and loading are concerned. It is the document released by the manufacturer and given to the operator with the aircraft that contains all necessary information to determine loading instructions or to produce the Load and Trim Sheet. The purpose of this chapter is to present the information included in the WBM. This document is divided into three sections : − 0.00 Arrangement of introduction pages, which contains all the pages describing the manual (Table of contents, List of figures …), − 1. Weight and balance control, which describes generic weight and balance data for the concerned aircraft, − 2. Aircraft weighing reports, which gives the results of the aircraft weighing (Operating Empty Weight and corresponding CG position). B. WEIGHT AND BALANCE MANUAL 108 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G B. WEIGHT AND BALANCE MANUAL 1. SECTION 1 : WEIGHT AND BALANCE CONTROL This section is divided into ten parts. 1.1. 1.00: GENERAL This part of the WBM presents first generic information such as a list of abbreviations, different weight definitions and conversion factors. Then it provides drawings and a description of the general characteristics of the aircraft. • ex A330-200: page 1.00.05, main aircraft dimensions Two other pieces of information can be found in section 1.00 : − An important graph on page 1.00.09: the stabilizer trim wheel setting. This graph enables to determine the correct trim setting according to the aircraft CG prior to take-off. B. WEIGHT AND BALANCE MANUAL Getting to Grips with Aircraft Weight and Balance 109 W E I G H T A N D B A L A N C E E N G I N E E R I N G A IR C R A F T W E IG H T (T O N S ) − The effect of moving components (1.00.10) is used to determine the influence of the landing gear retraction and/or flaps/slats extension on the aircraft CG position (see B3.1 Principle of Error calculation). • ex : A330-200 1.2. 1.10: LIMITATIONS This chapter deals with the different weight and balance limitations applied to the aircraft. The first ones are certified limits, i.e. the maximum weights (1.10.01) and the certified CG limits (charts and diagrams 1.10.02). These certified CG limits are the starting point for the determination of the operational flight envelope. • ex : A330-200 Other limitations are linked to payload carriage: − the permissible limits for shear loads and bending moments due to payload (1.10.03) and − the maximum weights that can be transported or loaded on cabin floor or on cargo compartment floor (1.10.04 floor loading limits). B. WEIGHT AND BALANCE MANUAL 110 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • ex : A330-200 − the paragraphs 1.10.05 to 1.10.07 deal with cargo compartment loading and give rules and recommendations for weight limitation, location, tying down of each load type (number of containers, maximum weight, load factors, …) and additional limitations in case of latch failure(s). • ex : A330-200 Last paragraphs deal with aircraft stability during weighing and loading: − 1.10.08 : maximum jacking loads − 1.10.09 : aircraft stability on jacks − 1.10.10 : aircraft stability on wheels B. WEIGHT AND BALANCE MANUAL Getting to Grips with Aircraft Weight and Balance 111 W E I G H T A N D B A L A N C E E N G I N E E R I N G 1.3. 1.20: FUEL This chapter of the WBM describes the influence on the aircraft CG position of the use of the fuel systems (refueling and fuel burn). The first part (1.20.01) describes briefly the aircraft fuel system : the arrangement of the tanks and the collector positions, fuel circulation within the different tanks during refueling and defueling. The last part of the introduction is the following : • A310, A320 family, A330/340 family • A300, A300-600 C. Fuel volume, density and weight All fuel quantities in this manual are in liters, and all fuel weights are based on a fuel density of 0.782 kg per liter unless otherwise specified. It is important to note the value of the density used in the WBM, because variations in actual fuel density due to specific gravity and temperature may result in large weight variations relative to those given in the manual. The second part (1.20.02) of the chapter details the aircraft refueling of tanks sequence : • ex : A330-200 Using this sequence it is possible to determine for each fuel quantity on board the aircraft, how much fuel each tank contains. B. WEIGHT AND BALANCE MANUAL 112 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • ex : A330-200 Selected Fuel quantity 65 000 kg 25 650 kg per inner tank outer full : 2 865 kg per outer tank (density : 0.785 kg/l) 0 kg in center tank 2 400 kg in trim tank As noted below the graph in this example : − Points #, $ and % are fixed in weight (kg or lb) irrespective of fuel density. − Points &, ' and ( are variable depending of fuel density. This explains why for one selected fuel quantity there might be more or less fuel in a given tank depending on the fuel density value. This is particularly appreciable for A330/340, A310 and A300-600R aircraft that is to say aircraft with fuel tank in the horizontal stabilizer. In addition to the above graph, a second graph presents the variations of the CG position of the fuel loaded on aircraft and a table gives all the coordinates of this graph. Note : the table and the corresponding graph are designed for the WBM standard fuel density (0.785 kg/l or 0.782 kg/l), whenever this table needs to be done for another density all break points (cf example points &, ' and () that depend on fuel density have to be recalculated with the corresponding fuel quantities. The third part of the chapter details the usable fuel (1.20.03) quantities and the corresponding H-arm values for each tank. This paragraph data is independent of the fuel density value. B. WEIGHT AND BALANCE MANUAL Getting to Grips with Aircraft Weight and Balance 113 W E I G H T A N D B A L A N C E E N G I N E E R I N G • ex : A330-200 Note 1: For inner and outer tanks the quantity is given per side. Note 2: In addition to the tables graphs showing the Fuel CG H-arm and Y-arm are provided. Last paragraphs deal with: − 1.20.04 : Unusable fuel − 1.20.05 : Unpumpable fuel − 1.20.06 : Defueling procedure prior to weighing B. WEIGHT AND BALANCE MANUAL 114 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 1.4. 1.30: FLUIDS This section contains information on the fluids on board the aircraft: − Engine fluids − APU oil − Hydraulic systems fluids − Potable water − Toilet fluids The WBM gives information on the weight and the H-arm of the fluids. • ex : A330-200 1.5. 1.40: PERSONNEL This section contains weight and balance information for the flight crew, the cabin crew and the passengers. For each category the H-arm of each person is given. The CG of each person is considered to be in the middle of the seat. The drawing of the cabin layout is on page 3 of section 1.40.03. In section 1.40.04 the position of all passenger seat rows is given. Last section in-flight movements (1.40.05) describes the method to determine the influence of in flight movement on the aircraft CG position. B. WEIGHT AND BALANCE MANUAL Getting to Grips with Aircraft Weight and Balance 115 W E I G H T A N D B A L A N C E E N G I N E E R I N G 1.6. 1.50: INTERIOR ARRANGEMENT This section on the WBM contains information on the different stowage capacities in the aircraft: the flight compartment stowage, cabin overhead stowage compartment, galleys with their contents (trolleys, boilers…), toilets and the cabin stowage compartments. In short, it describes all locations where some weight can be added in the upper deck area. For each location, the CG position of the weight is given as well as the maximum weight allowed. Note: for some stowage areas the maximum load value includes the stowage device weight (galleys, cabin stowage compartments,…). 1.7. 1.60: CARGO This section of the WBM deals with cargo loading. After a brief description of the cargo area division in holds, the first section (1.60.02) details the cargo hold doors opening sizes and stations. Then each cargo hold is fully described (1.60.03 forward hold, 1.60:04 aft hold, 1.60.05 bulk hold) : − Description of each loading device that can be loaded in the hold with its dimensions and position, − Tie down points identification and positions of the nets for bulk loading, − Limitations concerning package dimensions. Note : all information on cargo weight limitation is provided in chapter 1.10 LIMITATIONS. The last sections deal with methods and recommendations for cargo loading : − Tie down method (method used to determine the number of tie down points to be used for each cargo weight), − Gantry pallet transportation, − Split engine transportation, − Live animals transport, − Container transport, − Pallet transport. Note : the above mentioned paragraph can be present or not depending on the cargo option of the aircraft. B. WEIGHT AND BALANCE MANUAL 116 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Ex : A330-200 Average H-arm positions of the different ULD configurations Different ULD types usable in the hold with the appropriate position B. WEIGHT AND BALANCE MANUAL Getting to Grips with Aircraft Weight and Balance 117 W E I G H T A N D B A L A N C E E N G I N E E R I N G 1.8. 1.80: ACTIONS ON GROUND This section contains information on jacking points, weighing on jacks or on wheels, and CG calculations. It first describes the Weighing point locations (1.80.02) and then gives all formulae necessary to the calculation of the weight and CG of an aircraft weighed on wheels (1.80.04) and weighed on jacks (1.80.05). Section 1.80.06 gives the Equipment/component removal list: information on weight and H- arm of equipment normally removable from the aircraft for maintenance purposes. These equipment are parts of the wing (slats, flaps…), part of the engine pylon and nacelle, doors,… 1.9. 1.90: Examples Note 1 : the examples presented in this section are valid only for the balance scale presented in 1.00.05. Note 2 : the Typical loading diagram (1.90.04) is drawn on the aircraft certified limits diagram. It should be drawn on the operational limits diagram to take into account the aircraft CG movements due to CG determination errors and moving part transfer during flight. B. WEIGHT AND BALANCE MANUAL 118 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 2. SECTION 2 : WEIGHT REPORT This chapter contains the documents supplied with the aircraft at delivery: − 2.10 : Delivery weighing report which contains data to establish aircraft Operational Empty Weight (OEW) and Manufacturer Empty Weight (MEW) and corresponding CG positions. − 2.20 : Weighing check list which describes each item position and unit weight. In case the item is not present during aircraft weighing it should be mentioned in this section. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 119 W E I G H T A N D B A L A N C E E N G I N E E R I N G BALANCE CHART DESIGN INTRODUCTION The purpose of this section is to detail the whole process that leads to the production of a balance chart and of the corresponding AHM560. It first describes the calculation tools that are used (moment and index), then the calculation of the influence on aircraft CG of any item loading and finally the method to determine the aircraft operational limits. LOAD and TRIM SHEET A330-243 VERSION : 18 BC-264 YC DRY OPERATING WEIGHT CONDITIONS WEIGHT (kg) H-arm (m) I = (H-arm - 33.1555) x W 5000 + 100 DRY OPERATING WEIGHT INDEX AIRCRAFT REGISTER : DATE : PREPARED BY : FLT Nbr : CAPT. SIGNATURE : FROM : TO : DRY OPERATING WEIGHT WEIGHT DEVIATION (PANTRY) ± CORRECTED DRY OPERATING WEIGHT = CARGO + PASSENGERS + ZERO FUEL WEIGHT = TOTAL FUEL ONBOARD + TAKEOFF WEIGHT = ZONES E F G H WEIGHT DEVIATION (kg) BASIC INDEX CORRECTION ZONES DRY OPERAT. WEIGHT DEVIATION E F G H +300 kg -1.30 -0.82 +1.22 -300 kg +1.30 +0.82 -1.22 INDEX CORRECTION CORRECTED INDEX ALL WEIGHTS IN KILOGRAMS ZONES Nbr WEIGHT(kg) CARGO1 500 kg CARGO2 500 kg CARGO3 500 kg CARGO4 500 kg CARGO5 250 kg CABIN OA 10 PAX CABIN OB 40 PAX CABIN OC 15 PAX 70 80 90 100 110 120 130 140 INDEX FUEL INDEX - INDEX + SEE TABLE OVERLEAF NOTES TAKEOFF CG% MAC ZFW CDU INPUT WEIGHT (kg x 1000) AIRCRAFT CG % MAC 70 80 90 100 110 120 130 140 INDEX 110 120 130 140 150 160 170 180 190 200 210 220 230 A irc ra ft W e ig h t (k g x 1 0 0 0 ) 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Aircraft CG (%MAC) OPERATIONAL LIMITS TAKEOFF ZFW MTOW = 230000 kg MLW = 180000 kg MZFW = 168000 kg 18 20 22 24 26 28 30 32 34 36 38 40 7 6 5 4 3 2 1 0 %MAC PITCH TRIM Constant Constant Nose Down Nose Up . . . x 8 4 = INDEX CORRECTION ZONES E F G PAX OA (18 PAX) ROW 1 TO 3 OB (152 PAX) ROW 12 TO 31 OC (112 PAX) ROW 32 TO 46 CARGO 1 2 3 4 5 (3468 kg) (18869 kg) (15241 kg) 1 1 1 2 2 2 3 3 3 A A G1 G1c Ln 12 12 12 14 14 14 15 15 15 16 16 16 17 17 17 18 18 18 19 19 19 20 20 20 21 21 21 22 22 22 23 23 23 24 24 24 25 25 25 26 26 26 27 27 27 28 28 28 29 29 29 30 30 30 31 31 31 32 32 32 33 33 33 34 34 34 35 35 35 36 36 36 37 37 37 38 38 38 39 39 39 40 40 40 41 41 41 42 42 42 43 43 43 44 44 44 45 45 45 46 46 A A A A A A A A G2 G3 G5 G6 G7 Lh1 Lk1 Lk2 Lh2 Lp Lo C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 121 W E I G H T A N D B A L A N C E E N G I N E E R I N G C. BALANCE CHART DESIGN 1. MOMENT AND INDEX DEFINITIONS The purpose of the balance chart is to give an “easy way” to determine the influence on aircraft CG position of the loading of any item (passenger, cargo load, fuel, …). This “easy way” consists in introducing the notions of aircraft moment and item moment and consequently in defining the index. 1.1. Moment a) 1 Item moment : axis Reference to position CG item from Distance Weight Moment × ×× × = == = H-arm Origin H-arm = 0 CG W = item weight H-arm = item CG position H-arm Reference axis ( ) axis Reference Item arm H arm H Weight Moment − − − × = Note : in the whole process the moment notion has been simplified, normally a moment is determined by a Force multiplied by a distance. In this case the Force is simplified to the Mass of aircraft. Note : As common vocabulary uses Weight term instead of Mass, the wording is kept throughout the document. b) (Item1 +Item2) moment 2 1 2 1 Item Item ) Item Item ( Moment Moment Moment + = + C. BALANCE CHART DESIGN 122 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G c) HOW TO DETERMINE THE CG position of the set (Item+Additional item) ? Additional item weight = w CG position = h-arm Additional item Item weight = W CG position = h-arm Item Item + Additional item Final Weight = W + w’ Final CG position = h-arm Item + Additional item Origin H-arm = 0 h-arm Item h-arm Additional Item Final CG position H-arm Reference axis Moment item = W x (H-arm Item - H-arm Reference axis ) Moment additional item = w’ x (h-arm Additional item - H-arm Reference axis ) Moment item+additional item = (W+w’) x (H-arm Item+Additional item - H-arm Reference axis ) = + Moment Item+Additional Item (W + w’) x (H-arm Item+Additional item - H-arm Reference axis ) Moment Item W x (H-arm Item - H-arm Reference axis ) Moment Additional Item w’ x (h-arm Additional item - H-arm Reference axis ) = + ' w W arm H w' arm - H W arm - H Item Additional Item item Additional Item + − × + × = + d) ZFCG and TOCG determination So to determine the aircraft Zero Fuel and TakeOff CG positions we can use the following : Fuel Zero o arg c loaded passenger board on aircraft empty WEIGHT Moment Moment Moment ZFCG + + = Takeoff board on fuel o arg c loaded passenger board on aircraft empty WEIGHT Moment Moment Moment Moment TOCG + ++ + + ++ + + ++ + = == = To calculate each moment individually, a common reference axis has to be fixed. For all Airbus current aircraft the reference has been set for standard balance chart design at 25% of Mean Aerodynamic Chord as it is approximately in the middle of the certified envelopes of Airbus aircraft. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 123 W E I G H T A N D B A L A N C E E N G I N E E R I N G Item Weight = W H-arm = H item H item 25%MAC H-arm = H 25 Origin H-arm = 0 Reference axis ) H arm (H W Moment 25 item item − −− − − −− − × ×× × = == = Note : If an item is loaded forward to the reference the resulting moment will be a negative value (<0). If an item is loaded forward to the reference the resulting moment will be a positive value (>0). Note 2 : For the A380 as the certified limits will be more aft than for the other Airbus fleet aircraft the reference will be set at 35% of Mean Aerodynamic Chord. Nevertheless, the figures obtained when calculating each moment individually are very large and consequently not easy to manipulate. In order to reduce the figures of moments to a more workable magnitude, we use the Index. 1.2. Index a) Definition The index is a means to both reduce figures manipulated by the user, and represent the weight and the location of each item. K C H arm H W K C Moment I Index item item item item + ++ + − −− − − −− − × ×× × = == = + ++ + = == = = == = ) ( It is a value with no unit. In the following chapter it may appear as IU : Index Unit. Two constants appear in this formula: C: constant that allows having more workable figures. It has the same units as the moment (kg.m or lb.in). K: constant that is set so that the final ZF and TO index value is never negative. The value of these constants depends on the aircraft type and on the airline policy. But usually, Airbus applies the following constants to its aircraft: A300B2 / A300B4 A300-600 / A310 A318 A319 / A320 / A321 A330 / A340 A340-500 / A340-600 (kg.m) 2 000 1 000 500 1 000 2 500 5000 C (lb.in) 200 000 100 000 40 000 100 000 200 000 500 000 K 50 40 50 50 100 100 C. BALANCE CHART DESIGN 124 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G Note : two different index formulae can be used depending on the unit of item H-arm : length (m or in) or %MAC. K C ) 25 (%MAC Weight K C ) H arm (H Weight Index item 5 2 Item + ′ × − × = + − − × = with : C 100 RC of Length C × = ′ b) ∆ ∆∆ ∆Index : Index variation for any additional item loaded For any item loaded on board the aircraft, the index variation due to this specific loading can be determine ∆ ∆∆ ∆Index Additional Item Moment Additional Item C = c) ZF Index and TO Index determination So to determine the aircraft Zero Fuel and TakeOff index we can use the following : o arg c loaded passenger board on aircraft empty Index Index Index Index ZF ∆ + ∆ + = board on fuel o arg c loaded passenger board on aircraft empty Index Index Index Index Index TO ∆ + ∆ + ∆ + = Then it is possible to determine the moment corresponding to the resulting index and then the corresponding CG position. In the following paragraph, the method to determine the ∆Index for any item loaded on the aircraft is detailed (passengers, cargo, fuel, additional catering…). C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 125 W E I G H T A N D B A L A N C E E N G I N E E R I N G 2. INDEX VARIATION CALCULATION (∆ ∆∆ ∆INDEX) The index variation calculation is used to fill in the AHM560 document and to design the Balance Chart. 2.1. ∆ ∆∆ ∆Index for one item C ) H arm (H Weight C Moment ∆Index 25 item item item item − −− − − −− − × ×× × = == = = == = ∆Index is calculated for any person or item that can be loaded on board the aircraft. In the AHM560, ∆Index figures are usually given for 1 kg (or 1 lb) of weight. 1 Weight item = and item arm H− is read in the Weight and Balance Manual. 2.2. ∆ ∆∆ ∆Index for additional crew member WBM 1.40 Personnel chapter gives information on the position of all the flight and cabin crew seats. • Ex : A330-200 additional Flight crew member 100 K , m . kg 2500 C , m 1555 . 33 H 25 = = = kg / IU 00934 . 0 2500 ) 1555 . 33 8 . 9 ( C ) H 8 . 9 ( 1 ) kg 1 ( Index 25 occupant Third Crew Flight − = − = − × = ∆ So for one additional person in the cockpit (85 kg) : IU 794 . 0 ) kg 85 ( Index − = ∆ Note 1: the calculation principle is the same for cabin crew members. Note 2: in the AHM560, for cockpit crew members information is displayed as shown below. C. BALANCE CHART DESIGN 126 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 5. COCKPIT 5.1 Number of seats and average station Length of arm from reference station Maximum number of cockpit seats meters Index influence per 1 kg 4 -23.807 -0.00952 Remarks: The ∆Index value is given for the average H-arm of the 4 cockpit positions. 4 arm H arm H arm H arm H arm H occupant Fourth occupant Third Officer First Captain average Cockpit − + − + − + − = − C ) H arm H ( ) kg 1 ( Index 25 average Cockpit average Cockpit − − = ∆ 2.3. ∆ ∆∆ ∆Index for additional weight on the upper deck WBM 1.50 Interior Arrangement chapter describes the different stowage capacities in the flight and cabin compartments, the galleys and the toilets. This section gives information on the H-arm of each item: flight compartment stowage, overhead stowage compartments, cabin stowage compartments, galleys, toilet. • Ex : A330-200 galleys capacities and positions 100 K , m . kg 2500 C , m 1555 . 33 H 25 = = = kg / IU 00898 . 0 2500 ) 1555 . 33 714 . 10 ( C ) H 714 . 10 ( 1 ) kg 1 ( Index 25 b 1 G − = − = − × = ∆ Note : Each item H-arm represents the load CG position, it is usually located at the item barycentre. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 127 W E I G H T A N D B A L A N C E E N G I N E E R I N G 2.4. ∆ ∆∆ ∆Index for passenger boarding WBM 1.40 Personnel chapter gives information on the H-arm of each passenger seat row CG position. For each window seat row and each center seat row, the ∆Index is calculated. • Ex : A330-200 seat row positions Note : passenger seat CG is usually located in the middle of the seat. 100 K , m . kg 2500 C , m 1555 . 33 H 25 = = = kg / IU 00745 . 0 2500 ) 1555 . 33 520 . 14 ( C ) H 520 . 14 ( 1 ) kg 1 ( Index ) kg 1 ( Index kg / IU 00771 . 0 2500 ) 1555 . 33 885 . 13 ( C ) H 885 . 13 ( 1 ) kg 1 ( Index 25 RH 2 row seat Window LH 2 row seat Window 25 1 row seat Center − = − = − × = ∆ = ∆ − = − = − × = ∆ These ∆Index values per kg are presented in the AHM560, nevertheless on the manual balance chart it is not possible to take into account the ∆Index of each individual row. So the aircraft cabin is divided into several sections (usually 2 to 4 parts) and a generic influence is determined for each cabin. • Ex : A330-200 Cabin OA influence CABIN OA CABIN OB CABIN OC First step is to determine each cabin weighted average H-arm. ( (( ( ) )) ) ( (( ( ) )) ) m 5 . 16 32 4 arm H 4 arm H 2 arm H 2 arm H 2 arm H arm H 6 W 1 W 6 C 2 C 1 C OA = == = × ×× × − −− − + ++ + + ++ + × ×× × − −− − + ++ + × ×× × − −− − + ++ + + ++ + × ×× × − −− − + ++ + × ×× × − −− − = == = − −− − K K kg / IU 00666 . 0 2500 ) 1555 . 33 5 . 16 ( C ) H 5 . 16 ( 1 ) kg 1 ( Index 25 OA Cabin − = − = − × = ∆ C. BALANCE CHART DESIGN 128 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 2.5. ∆ ∆∆ ∆Index for cargo loading WBM 1.60 Cargo chapter gives information on the H-arm of cargo CG position for each cargo type (container, pallets or bulk). For each cargo type on each cargo position the ∆Index is calculated. • Ex : A330-200 AFT cargo compartment positions Position 31 Containers : H-arm average =37.607 m kg / IU 00178 . 0 2500 ) 1555 . 33 607 . 37 ( C ) H 607 . 37 ( 1 ) kg 1 ( Index ) kg 1 ( Index ) kg 1 ( Index 25 L 31 R 31 31 + = − = − × = ∆ = ∆ = ∆ Pallets 88” : H- arm average =37.958 m kg / IU 00192 . 0 2500 ) 1555 . 33 958 . 37 ( C ) H 958 . 37 ( 1 ) kg 1 ( Index 25 " 88 Pallet P 31 + = − = − × = ∆ C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 129 W E I G H T A N D B A L A N C E E N G I N E E R I N G Pallets 96” : H-arm average =38.095 m kg / IU 00198 . 0 2500 ) 1555 . 33 095 . 38 ( C ) H 095 . 38 ( 1 ) kg 1 ( Index 25 " 96 Pallet P 31 + = − = − × = ∆ Note : Each item H-arm represents the load CG position, it is usually located at the ULD barycentre for non bulk cargo and at the cargo position surface barycentre for bulk cargo. These ∆Index values per kg are presented in the AHM560, nevertheless on the manual balance chart it is not possible to take into account the ∆Index of each individual cargo position and each individual cargo type. So the cargo loaded is divided into cargo holds and a generic influence is determined for each hold. • Ex : A330-200 AFT cargo holds CARGO HOLD 3 CARGO HOLD 4 First step is to determine each cargo hold weighted average H-arm. Containers : Max weight = 2x1587 kg = 3174 kg Pallets 88” : Max weight = 4626 kg Pallets 96” : Max weight = 5103 kg ( ) ( ) ( ) m 225 . 39 5103 2 4626 2 3174 3 5103 H H 4626 H H 3174 H H H H " 96 P 32 " 96 P 31 " 88 P 32 " 88 P 31 33 32 31 3 o arg C = × + × + × × + + × + + × + + = kg / IU 00243 . 0 2500 ) 1555 . 33 225 . 39 ( C ) H 225 . 39 ( 1 ) kg 1 ( Index 25 3 o arg C + = − = − × = ∆ C. BALANCE CHART DESIGN 130 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 2.6. ∆ ∆∆ ∆Index for fuel loading Weight & Balance Manual section 1.20 (“Fuel”) provides with information on the aircraft fuel tanks, the H-arm of the fuel in each individual fuel tank for each fuel quantity and describes the automatic refueling sequence. From this data it is possible to determine for each total fuel quantity, on the first hand the fuel quantity that will be in each tank after the refueling sequence is completed and on the second hand the corresponding total fuel CG position. Last, for each total fuel quantity the ∆Index is calculated. a) Determination of the fuel distribution per tank after the refueling process First it is necessary to know the fuel quantity in each tank depending on the total selected fuel on board. Thanks to the automatic refueling system, the fuel dispatch among the several tanks of the aircraft is automatic and leads always to the same fuel distribution in each tank for a given total fuel quantity and a given fuel density. • Ex : WBM A330-200 refueling sequence In WBM section 1.20.02 page 1, a graph (established at the standard fuel density of 0.785 kg/l) and a written procedure (irrespective of fuel density) summarize the refueling sequence: from a given total fuel quantity (in kg), the fuel quantity that will be dispatched by the automatic refueling system in each individual tank can be deduced. For instance the automatic refueling procedure on A330-200 aircraft (equipped FCMS standard 7.0) is: - inner tanks refueled up to 3000kg per side (to fill in the collector cells) - outer tanks refueled to full - inner tanks refueled up to total fuel equals 36500 kg - trim tank refueled up to 2400 kg - inner tank refueled to full - trim tank and center tanks are simultaneously refueled up to full. Inner qty = 25935 kg Outer qty = 2865 kg Trim qty = 2400 kg Total fuel qty = 60000 kg C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 131 W E I G H T A N D B A L A N C E E N G I N E E R I N G In the above example, FOB = 60000 kg. It leads to the following fuel tank distribution (when the fuel density is equal to 0.785 kg/l): Inner (one side) : 25935 kg Outer (one side) : 2865 kg corresponding to full outer (3650 liters) at the standard fuel density 0.785 kg/l Trim : 2400 kg As the automatic refueling sequence contains break points defined in volume (outer tanks are fueled to high level shut-off for instance), the corresponding fuel quantity in weight will depend on the fuel density. On the above example, if the density were 0.76 kg/l, then the outer weight would have been 2774 kg and so the inner weight would have been 26026 kg: kg 26026 2 2400) 2 (2774 60000 ht Inner_weig = == = + ++ + × ×× × − −− − = == = per side Consequently, the fuel weight distribution per tank depends on the fuel density. C. BALANCE CHART DESIGN 132 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G b) Determination of the fuel CG position per tank after the refueling process Once the fuel weight distribution per individual tank is known, the fuel CG per tank can be deduced thanks to individual fuel tank table published in WBM section 1.20.03. To do so, we need to convert the fuel weight in each tank in term of volume per tank. In fact, the fuel CG position per tank depends on the fuel volume in it. As a general fact, because to the fuel tanks shape the fuel CG in the tank depends on the actual fuel quantity in it. .That is why WBM individual fuel tank tables give the H-arm of the tank as a function of the fuel volume. • Ex : WBM A330-200 Table of Fuel H-ARM Outer tanks Corresponding to 2865 kg at fuel density = 0.785 kg/l Outer fuel CG position is obtained Back to the previous example, the outer fuel quantity (one side) was 2865 kg, i.e. 3650 l at 0.785 kg/l. The corresponding H-arm is therefore 38.579 m for both outer tanks (same quantity in both tanks). Using corresponding tables for inner and trim tanks, we can deduce: Inner: 25935 kg centered at 31.287 m Trim: 2400 kg centered at 59.096 m. Thanks to these individual fuel tank tables, we can now determine the total fuel CG position equal to the weighted average of the individual tank CG positions. Total fuel = 60000 kg Outer (one side) = 2865 kg centered at 38.579 m Inner (one side) = 25935 kg centered at 31.287 m Trim = 2400 kg centered at 59.096 m The total fuel CG position is: m 33.096 60000 59.096 2400 31.287 25935 2 38.579 2865 2 G TotalFuelC = == = × ×× × + ++ + × ×× × × ×× × + ++ + × ×× × × ×× × = == = C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 133 W E I G H T A N D B A L A N C E E N G I N E E R I N G c) Determination of the fuel vector after the refueling process The above process needs to be repeated for total fuel quantities from zero to full. In the Weight and Balance Manual the result is displayed in a graph with fuel quantity in liter on vertical axis and H-ARM in meter on horizontal axis : the fuel vector. It is important to note that this fuel vector depends on the fuel density. In fact, weight break points of the automatic refueling sequence lead to different volumes according to the fuel density and so, the shape of the fuel vector is impacted. In the WBM, the automatic refueling fuel vector is represented only at the standard fuel density: 0.785 kg/l. To obtain fuel vector at another fuel density, the whole above process has to be repeated for different values of automatic refueling sequence break points. • Ex : WBM A330-200 Automatic Refueling Fuel Vector at standard fuel density 0.785 kg/l 76433 liters (corresponding to 60000 kg at standard fuel density) 33.093 meters (corresponding to 60000 kg fuel CG position) Thanks to the fuel vector and for a given fuel density (here, 0.785 kg/l), for any fuel quantity, the corresponding fuel CG position can be easily found. As per previous example, for 60000 kg FOB (equivalent to 76433 liter at fuel density 0.785 kg/l) the corresponding fuel CG position is 33.093m (as computed above). C. BALANCE CHART DESIGN 134 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G d) Determination of the fuel vector expressed in ∆ ∆∆ ∆Index after the refueling process Now, for Balance Chart production purpose, we need to have this fuel vector expressed in ∆Index as a function of the fuel weight. This is realized converting the volume values into weight values and converting H-arm values into ∆Index. C ) H arm (H W ∆Index Ref fuel Fuel Weight fuel − −− − − −− − × ×× × = == = , A new fuel vector is obtained giving for any fuel weight the impact in term of ∆Index. As for the WBM fuel vector (expressed in H-arm as a function of the fuel volume), this new fuel vector depends also on the fuel density. The below graph presents two fuel vectors for two different fuel densities: the standard one 0.785kg/l and a higher one 0.83 kg/l. The differences between the two fuel vectors are due to the definition of the break points of the automatic refueling sequence. Then, these differences are more important at break points where the involved tank(s) has (have) either a great capacity or a great lever arm compared to the lever arm reference. • Ex : A330-200 Automatic Refueling Fuel Vector Weight Index Fuel Vectors : 0.76 kg/l 0.785 kg/l 0.83 kg/l 1 2 3 4 5 6 From the above graph, it can be noted that the fuel density variation has a double effect on the fuel vector: 1. A vertical distortion (weight distortion) increasing with the fuel quantity and affecting points defined in volume (2, 5 and 6) 2. A horizontal distortion (index distortion) increasing with the tank H-arm compared to H Ref and affecting point defined in weight (1, 3 and 4). C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 135 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3. OPERATIONAL LIMITS DETERMINATION 3.1. Calculation principle The determination of the aircraft CG position using a paper or computerised trim sheet is affected by inaccuracy on the influence of item loading on the final aircraft CG position. Furthermore the aircraft CG position changes during flight because of different items moving (landing gear,…) Before flight the aircraft CG position must be checked against the three certified envelopes. Due to the CG position uncertainties some margins must be determined between the certified envelopes and the ones used on the trim sheet : the operational limits. On the balance chart the 3 operational limits – Takeoff, Landing and In-flight – are not represented because even if the Takeoff CG position check against its corresponding limit can be done after a manual or computerized computation, the determination of the Landing CG and furthermore the In-flight CG positions on a paper document is much more difficult, it is impossible to check these CG positions against their corresponding CG limits. So on balance charts two operational limits are represented : − Operational Takeoff limit − Operational Zero Fuel limit The Zero Fuel limit is determined to ensure that during the whole flight and at landing the aircraft CG remains within the limits. 3.2. Margins determination method 3.2.1. Method To determine the aircraft ZFW, TOW and CG position during flight one needs to know : − aircraft CG position and weight before loading any item − weight and position of each item loaded on the aircraft (cargo, pax, fuel, any additional item) − possible CG movements due to moving items during flight. An inaccuracy on the final CG value can be introduced because of a lack of precision either on item weight, or on its location and/or CG position. The total possible inaccuracy made on CG estimation will result of a combination of all the individual errors : − due to initial conditions (aircraft DOW and DOCG) − due to cargo loading − due to passenger boarding − due to fuel loading. In addition to these inaccuracy sources, the method used to determine the aircraft CG may also add an inaccuracy source if it needs index rounding or index interpolation. CERTIFIED LIMITS OPERATIONAL LIMITS Operational margin C. BALANCE CHART DESIGN 136 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G The aircraft ZFW, TOW and CG position computation is based on initial aircraft configuration corresponding to DOW and DOCG. Due to some item movements during the flight the aircraft configuration may change, this CG movement needs to be taken into account in the operational limits determination. Operational margins are the sum of the total possible inaccuracy and the possible aircraft CG movements due to : − landing gear movements − flaps/slats movements − water movements − movements in the cabin. Operational Limits 35000 40000 45000 50000 55000 60000 65000 70000 75000 80000 20 70 INDEX A i r c r a f t W e i g h t ( k g ) Operational envelope Certified envelope Operational Margin The following paragraphs detail each error and CG movement evaluation. The method is to determine the influence that each lack of precision or each CG movement will have on the aircraft final CG position. This influence can be quantified as the difference between the trimming document final index and the index that would result of a calculation with no accuracy. Instead of using the index value the following method uses the moment and evaluate difference between the aircraft moment determined using the trimming document (assumed) and the real one. Operational margins = (Real Aircraft Moment) – (Assumed Aircraft Moment) Note : inaccuracies and movements can shift the aircraft CG forward or aft. If the CG shifts forward the CG H-arm decreases and so the resulting moment also decreases. The inaccuracy shifting the CG forward reduces the aircraft total moment so this inaccuracy or movement results in a negative moment. CG moves FWD moment < 0 CG moves AFT moment > 0 C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 137 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.2.2. Resulting moments determination After evaluating the individual moments corresponding to each lack of precision and/or to each movement it is necessary to determine their total effect in term of moment. This total effect definition depends on the type of situation. Lets consider the total effect (E) is made of several individual effects E 1 , E 2 ...E n. e.g. The resulting cargo loading effect is the made of the effects due to the different cargo compartments. When the individual effects are SYSTEMATIC (if they occur surely at each flight) then they will CUMULATE and the total effect is, E = E 1 +E 2 +...+E n it is also said they are NON RANDOM or DEPENDENT, When the individual effects are NON SYSTEMATIC (if they may occur or not at each flight) then they can COMPENSATE and the total effect is, E = n 2 2 2 1 2 E + ... + E + E it is also said they are RANDOM or INDEPENDENT, When effects are non-systematic, they can compensate each other and the resulting error is always less important with independent effects than with systematic effects. Note : Sometimes, the two types of effects may be mixed. This occurs for the final calculation per flight phase. C. BALANCE CHART DESIGN 138 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.3. Inaccuracy on initial data (DOW and DOCG) 3.3.1. Dry Operating Weight (DOW) definition : a) DOW and DOCG definition policy At delivery each aircraft is weighed to determine its Manufacturer’s Empty Weight (MEW) and the Corresponding CG position. Using these values the operator can determine the aircraft Dry Operating Weight (DOW) and the corresponding CG position of each aircraft. When defining the DOW and DOCG to be used in the loading and trimming documents the operator has two choices: 1. considering each aircraft as independent so for each aircraft an individual set of values (DOW and DOCG) is set 2. considering a group of aircraft as being part of one fleet so one single set of values (DOW fleet and DOCG fleet ) is defined and used in the loading and trimming documents. As per aviation regulations a fleet of aircraft can be defined provided that, for each aircraft of the fleet, DOW aircraft and DOCG aircraft meet the allowed deviations to the fleet values : A DOW maximum deviation of ± 0.5% of the aircraft Maximum Landing Weight A CG position maximum deviation of ± 0.5% of the Reference Chord length Note : in other words : an aircraft can be part of a fleet as long as DOW fleet – 0.5%MLW ≤ DOW aircraft ≤ DOW fleet + 0.5%MLW DOCG fleet – 0.5%Length of RC ≤ DOCG aircraft ≤ DOCG fleet + 0.5%Length of RC Then during the aircraft life, between two weighings, its weight and CG position can be modified following maintenance tasks or cabin interior modifications, paintings. In that case the DOW and DOCG values used to enter the loading and trimming documents should be amended. As per aviation regulations the DOW document and DOCG document values amendment is mandatory as soon as DOW document – 0.5%MLW ≤ DOW aircraft ≤ DOW document + 0.5%MLW DOCG document – 0.5%Length of RC≤ DOCG aircraft ≤ DOCG document + 0.5%Length of RC b) Inaccuracy on initial data In conclusion to the above statements, the DOW and DOCG assumed used in the loading and trimming documents is the aircraft one with a tolerable inaccuracy of ±0.5%MLW for the weight and ±0.5% of the Reference Chord length for the CG position. • Ex: A320 in the following configuration: MLW = 64 500 kg, DOW = 39 400 kg RC = 4.1935 m The weight allowance is ±0.5 % of 64 500 kg = ±322.5 kg The CG position allowance is ±0.5 % of 4.1935m = ±0.0210 m Then the aircraft weight and CG position can vary within the following values: DOW document - 322 kg ≤ DOW ≤ DOW document + 322 kg DOCG document - 0.021 m ≤ CG ≤ DOCG document + 0.021 m C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 139 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.3.2. Effect on the final aircraft CG position The inaccuracy on the aircraft initial CG position will generate an inaccuracy on the final CG position (ZFCG or TOCG) which can be determined in term of moment (E DOCG ) E DOCG = Real Aircraft Moment – Assumed Aircraft Moment E DOCG = DOW real x (H-arm real – H 25 ) – DOW assumed x (H-arm assumed – H 25 ) In the following we consider that DOW real ≈ DOW assumed so E DOCG = DOW assumed x (H-arm real – H 25 ) – DOW assumed x (H-arm assumed – H 25 ) E DOCG = DOW assumed x (H-arm real – H-arm assumed ) As per regulation (H-arm real – H-arm assumed ) cannot exceed ±0.5% of the Reference Chord length. 100 Length 5 . 0 DOW E Chord ference Re assumed DOCG × ± × = Note : the effect value depends on the DOW assumed so each time the DOW has to be changed the effect needs to be recalculated and so the total effect on the aircraft CG determine shall be modified also. In order to avoid continuous balance documentation modification, the operator can take a weight value of (DOW assumed + margin) including the possible weight modifications. ( ) 100 Length 5 . 0 in arg m DOW E Chord ference Re assumed DOCG × ± × + = • Ex: A320 in the following configuration: MLW = 64 500 kg, DOW = 39 400 kg RC = 4.1935 m ( ) kg . m 910 100 1935 . 4 5 . 0 4000 39400 E DOCG ± = × × + = C. BALANCE CHART DESIGN 140 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.4. Inaccuracy on items loading on board the aircraft (passengers, cargo, fuel) Any item loaded onboard the aircraft has a given weight and location. Nevertheless, this weight and/or CG position might not be known with enough precision. So there is an inaccuracy in the determination of the delta index due to the item loading which is due to an inaccuracy on either the item weight or on the item location. In the following paragraphs the method to determine the effect of each inaccuracy is developed. Note : Effects are supposed to be independent : location is supposed to be accurately known to calculate the effect of the error in weight, and the weight is supposed to be accurately known to determine the effect of the error on location. • Inaccuracy on the item location The inaccuracy on the item position generates an inaccuracy on the final aircraft CG position that can be determined in terms of moment (E item location ). Note : the item weight is considered to be accurately known. E item location = Real Aircraft Moment – Assumed Aircraft Moment E item location = (Aircraft Moment + Real Item Moment) – (Aircraft Moment + Assumed Item Moment) E item location = Real Item Moment – Assumed Item Moment E item location = W item x (H-arm item real – H-arm ref ) – W item x (H-arm item assumed – H-arm ref ) E item location = W item x (H-arm item real – H-arm item assumed ) • Inaccuracy on the item weight Each item weight is known with a certain inaccuracy (∆W Item ) so for each item : W item real = W item assumed ± ∆W Item The inaccuracy on the item weight generates an inaccuracy on the final aircraft weight and CG position that can be determined in term of moment (E item weight ). The inaccuracy value depends on the relation between the position of the ∆W Item and the assumed position of the aircraft final CG − If the ∆W Item is forward of the assumed aircraft final CG then a positive weight inaccuracy +∆W Item will move the CG forward, a negative weight inaccuracy - ∆W Item will move the CG aft a/c CG assumed a/c W assumed +∆ ∆∆ ∆W Item a/c CG W+∆ ∆∆ ∆WItem a/c W+∆ ∆∆ ∆W Item C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 141 W E I G H T A N D B A L A N C E E N G I N E E R I N G − If the ∆W Item is aft of the assumed aircraft final CG then a positive weight inaccuracy +∆W Item will move the CG aft, a negative weight inaccuracy -∆W Item will move the CG forward a/c CG assumed a/c W assumed a/c CG W-∆ ∆∆ ∆WItem a/c W-∆ ∆∆ ∆W Item -∆ ∆∆ ∆W Item Note : the item position is considered to be accurately known. The ∆W Item impact is critical when the aircraft assumed CG is close to the limits, because the weight inaccuracy may lead to a real CG out of the limits. • Eg : impact of ∆ ∆∆ ∆W Item if ∆ ∆∆ ∆W Item is located in front of CG assumed . Positive weight inaccuracy : +∆W Item a/c CG assumed a/c W assumed a/c CG W+∆ ∆∆ ∆WItem a/c W+∆ ∆∆ ∆W Item a/c FWD CG limit a/c AFT CG limit ∆ ∆∆ ∆W Item located in front of a/c CG assumed a/c CG assumed a/c W assumed a/c CG W+∆ ∆∆ ∆WItem a/c W+∆ ∆∆ ∆W Item a/c FWD CG limit a/c AFT CG limit ∆ ∆∆ ∆W Item located in front of a/c CG assumed non critical situation critical situation Negative weight inaccuracy : -∆W Item a/c CG assumed a/c W assumed a/c CG W-∆ ∆∆ ∆WItem a/c W-∆ ∆∆ ∆W Item a/c FWD CG limit a/c AFT CG limit ∆ ∆∆ ∆W Item located in front of a/c CG assumed a/c CG assumed a/c W assumed a/c CG W-∆ ∆∆ ∆WItem a/c W-∆ ∆∆ ∆W Item a/c FWD CG limit a/c AFT CG limit ∆ ∆∆ ∆W Item located in front of a/c CG assumed non critical situation critical situation C. BALANCE CHART DESIGN 142 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G The impact in term of moment (E item weight ) of this inaccuracy is determined by the difference between the aircraft real moment at aircraft weight : W item assumed ± ∆W Item and the aircraft moment if the aircraft CG remains in the limit at aircraft weight : W item assumed ± ∆W Item . a/c CG assumed a/c W assumed a/c CG W+∆ ∆∆ ∆WItem a/c W+∆ ∆∆ ∆W Item a/c CG limit a/c W+∆ ∆∆ ∆W Item E item weight E item weight is maximum when a/c CG assumed is on the aircraft CG limit. a/c CG assumed a/c W assumed a/c CG W+∆ ∆∆ ∆WItem a/c W+∆ ∆∆ ∆W Item a/c CG limit a/c W+∆ ∆∆ ∆W Item E item weight So E item weight is determined by the difference between the moment of the aircraft ± ∆W Item on board and the moment of the aircraft at (W aircraft assumed ± ∆W Item ) in case ± ∆W Item has no impact on the aircraft CG, in other words in the case when with the inaccuracy in weight the aircraft CG remains at the same position, on the limit. E item weight = (Moment aircraft assumed +Moment ∆Witem ) – Moment aircraft on the limit E item weight = [W aircraft x (H-arm aircraft - H-arm Ref ) ± ∆W Item x (H-arm ∆Witem - H-arm Ref )] - (W ± ∆W Item ) x (H-arm aircraft – H-arm Ref ) E item weight = ± ∆W Item x (H-arm ∆Witem - H-arm aircraft ) With H-arm aircraft = H-arm limit E item weight = ± ±± ± ∆ ∆∆ ∆W Item x (H-arm ∆ ∆∆ ∆Witem - H-arm limit ) Determining the E item weight value consists of checking the different possible H-arm limit to determine the more limiting E item weight . C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 143 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.4.1. Inaccuracy on cargo loading on board the aircraft a) Inaccuracy on the cargo location For cargo loading, two sources of inaccuracies have to be considered. − On the one hand, on the balance chart the cargo influence is taken into account as a delta index per cargo compartment (CARGO 1, CARGO2…), this delta index is based on an average H-arm for the corresponding compartment. Now the real loading may have an average H-arm different from the average one. This difference will generate an inaccuracy on the aircraft CG determination. This inaccuracy is named cargo distribution inaccuracy. − On the other hand, when determining the average cargo compartment H-arm, each cargo position CG is known with a certain inaccuracy, this inaccuracy will generate an inaccuracy on the aircraft CG determination. This inaccuracy is named cargo CG tolerance inaccuracy. • Cargo distribution inaccuracy: E item location = W item x (H-arm item real – H-arm item assumed ) For this inaccuracy determination the different loading scenarios have to be studied. For each of them, E item location is determined with H-arm item assumed being H-arm CargoX and H-arm item real being the H-arm of the studied configuration. The process for checking the different configuration is the following : − Determine the cargo compartment average H-arm : refer to paragraph 2.5 ∆Index for cargo loading. − Study each configuration separately (containers, pallets 88”, pallets96” and/or Bulk) − For each configuration the forward inaccuracy is determined when all the positions in front of the average H-arm are full and all the positions aft of the average H-arm are empty. − For each configuration the aft inaccuracy is determined when all the positions aft of the average H-arm are full and all the positions in front of the average H-arm are empty. − Determine the configuration generating the highest inaccuracy. This inaccuracy needs to be determined for each cargo compartment that is represented on the balance chart. Then the total inaccuracy is determined considering each cargo compartment inaccuracy independent from the other ones. fwd cargo5 2 fwd cargo4 2 fwd cargo3 2 fwd cargo2 2 fwd cargo1 2 fwd n distibutio cargo E + E + E + E + E E − −− − = == = aft cargo5 2 aft cargo4 2 aft cargo3 2 aft cargo2 2 aft cargo1 2 aft n distibutio cargo E + E + E + E + E E + ++ + = == = Note : when an EDP system is used to compute the aircraft CG position and weight, then the cargo delta index may be determined for each individual cargo position, in this case the cargo distribution inaccuracy is nil. C. BALANCE CHART DESIGN 144 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Example Cargo 1 inaccuracy for configuration with 5 ULDs : Forward inaccuracy 12 H12 W12 CARGO 1 11 H11 W11 13 H13 W13 14 H14 W14 15 H15 W15 H-arm cargo 1 H-arm position 11 H-arm real loading : position11+position12 E item location = W item x (H-arm item real – H-arm item assumed ) E Cargo1 distribution fwd = W position11+position12 x (H-arm position11+position12 – H-arm cargo1 ) According to 2.5 ∆Index for cargo loading - 15 14 13 12 11 15 15 14 14 13 13 12 12 11 11 cargo1 W W W W W H W H W H W H W H W arm H + ++ + + ++ + + ++ + + ++ + × ×× × + ++ + × ×× × + ++ + × ×× × + ++ + × ×× × + ++ + × ×× × = == = − −− − - 12 11 12 12 11 11 position12 Position11 W W H W H W arm H + ++ + × ×× × + ++ + × ×× × = == = − −− − + ++ + and W position11+position12 = W position11 + W position12 Aft inaccuracy 12 H12 W12 CARGO 1 11 H11 W11 13 H13 W13 14 H14 W14 15 H15 W15 H-arm cargo 1 H-arm position 11 H-arm real loading : position13+position14+position15 E item location = W item x (H-arm item real – H-arm item assumed ) E Cargo1 distribution aft = W position13+position14+position15 x (H-arm position13+position14+position15 – H-arm cargo1 ) According to 2.5 ∆Index for cargo loading - 15 14 13 12 11 15 15 14 14 13 13 12 12 11 11 cargo1 W W W W W H W H W H W H W H W arm H + ++ + + ++ + + ++ + + ++ + × ×× × + ++ + × ×× × + ++ + × ×× × + ++ + × ×× × + ++ + × ×× × = == = − −− − - 15 14 13 15 15 14 14 13 13 position15 position14 Position13 W W W H W H W H W arm H + ++ + + ++ + × ×× × + ++ + × ×× × + ++ + × ×× × = == = − −− − + ++ + + ++ + and W position13+position14+position15 = W position13 + W position14 + W position15 C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 145 W E I G H T A N D B A L A N C E E N G I N E E R I N G • Ex: A320 bulk loading in the compartment 1. Determination of the average H-arm of the compartment 1: Position (Bulk) Maximum allowable Weight (kg) H-arm (m) MOMENT (kg.m) (W x H) 11 12 13 1045 1225 1132 10.744 12.433 13.971 11227.5 15230.4 15815.2 ∑ = 3402 42273.1 H-arm cargo1 = 12.426 m FORWARD INACCURACY: Position 11 is the only position in front of the average H-arm. E Cargo1 distribution fwd = W 11 x (H 11 – H cargo1 ) E Cargo1 distribution fwd = 1045 x (10.744 – 12.426) = – 1757.7 kg.m AFT INACCURACY: Position 12 and 13 are aft of the average H-arm. E Cargo1 distribution aft = W 12+13 x (H 12+13 – H cargo1 ) W 12+13 = W 12 + W 13 = 1225 + 1132 = 2357 kg m 14.260 1132 1045 1132 13.971 1045 12.433 W W W H W H H 13 12 13 13 12 12 13 12 = == = + ++ + × ×× × + ++ + × ×× × = == = + ++ + × ×× × + ++ + × ×× × = == = + ++ + E Cargo1 distribution aft = 2357 x (14.260 – 12.426) = + 4322.7 kg.m C. BALANCE CHART DESIGN 146 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Ex: A330-200 containerized loading in the compartment 1. The compartment 1 of the A330-300 has 3 individual positions (11, 12, 13). It can be loaded with: Either 6 containers LD3 (AKE) or 3 containers LD1 (AKC) or 3containers LD6 (ALF) Or 3 pallets 60.4 x 125 in (PKx) or 2 pallets 88 x 125 in (PAx) or 2 pallets 96 x 125 in (PMx) Containers (LD3, LD1 and LD6) and pallets PKx have the same lever arm. So, we will just use one of those ULDs, one allowing the highest loaded weight, in this example LD6. The following table gives the H-arm for each ULD position on the compartment 1. H-arm (m) Container (LD6) Pallet 88" Pallet 96" 11 or 11P 15.432 15.738 15.885 12 or 12P 17.218 18.450 18.348 POSITION 13 18.801 - - Maximum allowable weight (kg) per ULD 3174 4626 5103 The average center of gravity position of this compartment is 17.128 meters H cargo1 = 17.128 m. FORWARD INACCURACY: LD6 configuration Position 11 is the only position in front of the average H-arm. E Cargo1 distribution fwd = W 11 x (H 11 – H cargo1 ) E Cargo1 distribution fwd = 3174 x (15.432 – 17.128) = – 5383 kg.m Pallet 88” configuration Position 11P is the only position in front of the average H-arm. E Cargo1 distribution fwd = 4626 x (15.738 – 17.128) = – 6222 kg.m Pallet 96” configuration Position 11P is the only position in front of the average H-arm. E Cargo1 distribution fwd = 5103 x (15.885 – 17.128) = – 6343 kg.m The highest inaccuracy is obtained for Pallet 96” configuration, this value is retained as E Cargo1 distribution fwd = – 6343 kg.m AFT INACCURACY: LD6 configuration Position 12 and 13 are aft of the average H-arm. E Cargo1 distribution aft = W 12+13 x (H 12+13 – H cargo1 ) W 12+13 = W 12 + W 13 = 2 x 3174 = 6348 kg m 18 3174 3174 3174 18.801 3174 17.218 W W W H W H H 13 12 13 13 12 12 13 12 = == = + ++ + × ×× × + ++ + × ×× × = == = + ++ + × ×× × + ++ + × ×× × = == = + ++ + E Cargo1 distribution aft = 6348 x (18.0095 – 17.128) = + 5595 kg.m Pallet 88” configuration Position 12P is the only position in front of the average H-arm. E Cargo1 distribution aft = 4626 x (18.450 – 17.128) = + 6115 kg.m Pallet 96” configuration Position 12P is the only position in front of the average H-arm. E Cargo1 distribution aft = 5103 x (18.348 – 17.128) = + 6225 kg.m The highest inaccuracy is obtained for Pallet 96” configuration, this value is retained as E Cargo1 distribution aft = + 6225 kg.m Note: In this particular case (A330) the scenario with the highest inaccuracy corresponds to the heaviest pallets configuration, nevertheless it is not always the case and all scenarios need to be checked for each individual computation. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 147 W E I G H T A N D B A L A N C E E N G I N E E R I N G • Cargo CG tolerance inaccuracy: E item location = W item x (H-arm item real – H-arm item assumed ) For this inaccuracy determination the different loading scenarios have to be studied. For each of them, E item location is determined with (H-arm item real – H-arm item assumed ) being the allowed tolerance when loading a cargo position. E item CG tolerance = W item x tolerance This tolerance is described in the WBM for ULD loaded aircraft in section 1.10. For each ULD baseplate the CG is never right on the baseplate geometric center. The longitudinal allowance is equal to ±10% of the depth of the baseplate. For, bulk loaded aircraft the same principle is considered. The longitudinal allowance is equal to ±10% of the depth of the bulk position. The process for checking the different configuration is the following : − Study each configuration separately (containers, pallets 88”, pallets96” and/or Bulk) − For each configuration determine the total inaccuracy considering that the inaccuracy for each ULD/bulk position is independent from the other ones. E = n 2 2 2 1 2 E + ... + E + E − Determine the configuration generating the highest inaccuracy. C. BALANCE CHART DESIGN 148 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Ex: A330-200 containerized loading in the compartment 1. The compartment 1 of the A330-300 has 3 individual positions (11, 12, 13). It can be loaded with: Either 6 containers LD3 (AKE) or 3 containers LD1 (AKC) or 3 containers LD6 (ALF) Or 3 pallets 60.4 x 125 in (PKx) or 2 pallets 88 x 125 in (PAx) or 2 pallets 96 x 125 in (PMx) The longitudinal allowance for each type of ULD is : Container (LD3, LD1, LD6) ± 0.153 m (± 6.04 in) Pallet 88" (PAx: 88 x 125 in) ± 0.2235 m (± 8.8 in) Pallet 96" (PMx: 96 x 125 in) ± 0.244 m (± 9.6 in) The maximum allowable weight (kg) per ULD is Container (LD3, LD1) 1587 kg Container (LD6) 3174 kg Pallet 88" (PAx: 88 x 125 in) 4626 kg Pallet 96" (PMx: 96 x 125 in) 5103 kg LD3 configuration 6 LD3 can be loaded E item CG tolerance = W item x tolerance E LD3 CG tolerance = 1587 x ± 0.153 = ± 242.8 kg.m kg.m 594.8 6 242.8 6 E E 2 tolerance CG LD3 tolerance CG ion configurat LD3 ± ±± ± = == = × ×× × ± ±± ± = == = × ×× × ± ±± ± = == = LD1 configuration 3 LD1 can be loaded E item CG tolerance = W item x tolerance E LD1 CG tolerance = 1587 x ± 0.153 = ± 242.8 kg.m kg.m 420.5 3 242.8 3 E E 2 tolerance CG LD1 tolerance CG ion configurat LD1 ± ±± ± = == = × ×× × ± ±± ± = == = × ×× × ± ±± ± = == = LD6 configuration 3 LD6 can be loaded E item CG tolerance = W item x tolerance E LD6 CG tolerance = 3174 x ± 0.153 = ± 485.6 kg.m kg.m 841.1 3 485.6 3 E E 2 tolerance CG LD6 tolerance CG ion configurat LD6 ± ±± ± = == = × ×× × ± ±± ± = == = × ×× × ± ±± ± = == = Pallet 88” configuration 2 pallets can be loaded E item CG tolerance = W item x tolerance E Pallet 88” CG tolerance = 4626 x ± 0.2235 = ± 1033.9 kg.m kg.m 1462.1 2 1033.9 2 E E 2 tolerance CG Pallet88" tolerance CG ion configurat 88" Pallet ± ±± ± = == = × ×× × ± ±± ± = == = × ×× × ± ±± ± = == = Pallet 96” configuration 2 pallets can be loaded E item CG tolerance = W item x tolerance E Pallet 96” CG tolerance = 5103 x ± 0.244 = ± 1245.2 kg.m kg.m 1760.9 2 1245.1 2 E E 2 tolerance CG 96" Pallet tolerance CG ion configurat Pallet96" ± ±± ± = == = × ×× × ± ±± ± = == = × ×× × ± ±± ± = == = The highest inaccuracy is obtained for Pallet 96” configuration, this value is retained as E Cargo1 CG tolerance = ± 1760.9 kg.m Note: In this particular case (A330) the scenario with the highest inaccuracy corresponds to the heaviest pallets configuration, nevertheless it is not always the case and all scenarios need to be check for each individual computation. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 149 W E I G H T A N D B A L A N C E E N G I N E E R I N G b) Inaccuracy on the cargo weight Cargo weight is supposed to be known without inaccuracy : for freight loading airlines usually weight the pallets and container after they are prepared, then for baggage the total weight of baggage per flight is accurately known as each individual piece of luggage is weighed. So E cargo weight is usually supposed to be nil. Note : in case the cargo weight cannot be accurately known it may be needed to introduce a cargo weight inaccuracy, this inaccuracy may be due to the fact that the ULD weight is estimated and not weighed or to the fact that the baggage weight per cargo position is estimated, usually using an average weight per baggage piece. In the case a cargo weight inaccuracy is to be determined the method to be applied is similar to the one described in the next chapter for passenger weight inaccuracy. 3.4.2. Inaccuracy on passenger loading on board the aircraft a) Inaccuracy on the passengers’ location On the balance chart the passenger influence is taken into account as a delta index per passenger cabin section (CABIN OA, CABIN OB, …), this delta index is based on an average H- arm for the corresponding cabin section. Now the real loading may result in an H-arm different from the average one. This difference will generate an inaccuracy on the aircraft CG determination. This inaccuracy is named passenger distribution inaccuracy. • Passenger distribution inaccuracy: E item location = W item x (H-arm item real – H-arm item assumed ) E item location is determined with H-arm item assumed being H-arm CabinOX and H-arm item real being the H-arm of the real passengers seating configuration. The process for checking the different configuration is the following : − Determine the cabin section average H-arm : refer to paragraph 2.4 ∆Index for passenger boarding. − Determine the passenger seating configuration which generates a significant inaccuracy. The maximum inaccuracy would be determined when all seats in front of the average H-arm are full and all seats aft of the average H-arm are empty. But this boarding configuration is not a realistic one and the inaccuracy is in this case very high. So a realistic boarding scenario needs to be determined. H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC H-arm real passenger seating configurations C. BALANCE CHART DESIGN 150 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G The following boarding scenario is taken into account : − Passengers board first on (or ask first for) window seats. − Passengers board then on aisle seats − Finally passengers board on middle seats. Following this scenario the forward inaccuracy is determined when − Either all the window seats in front of the average H-arm are full and all the window seats aft of the average H-arm are empty. H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC H-arm real passenger seating configurations − Or all window seats are full and all the aisle seats in front of the average H-arm are full and all the aisle seats aft of the average H-arm are empty. H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC H-arm real passenger seating configurations − Or all window and aisle seats are full and all the center seats in front of the average H-arm are full and all the center seats aft of the average H-arm are empty. H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC H-arm real passenger seating configurations The aft inaccuracy is computed following the same passenger seating configuration but with passengers first seated in the rear part of the cabin section. Note : on the majority of cabin layouts the second option generates the highest significant inaccuracy. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 151 W E I G H T A N D B A L A N C E E N G I N E E R I N G The passenger distribution inaccuracy is determined for each cabin section that is represented on the balance chart. Then the total inaccuracy is determined considering each cabin section inaccuracy independent from the other ones. ... + E + E + E E fwd OC Cabin 2 fwd OB Cabin 2 fwd OA Cabin 2 fwd n distibutio passenger − −− − = == = ... + E + E + E E aft OC Cabin 2 aft OB Cabin 2 aft OA Cabin 2 aft n distibutio passenger + ++ + = == = Note : when an EDP system is used to compute the aircraft CG position and weight, then the passenger delta index may be determined for each individual passenger seat row, in this case the passenger distribution inaccuracy is nil. Note : when applying the realistic boarding scenario, it is considered that all the passenger seats are available. In some case airlines may decide that some seats must remain unoccupied, for example if one emergency exit is inoperative. In these specific cases passenger boarding may generate a higher inaccuracy than the one taken into account in the operational margin determination. It is worth taking in account additional margins for those specific cases. These margins are computed for each specific cabin layout and unoccupied seats configurations. • Ex : A320 forward inaccuracy with the following cabin layout ROW H.ARM (m) LHPAX RHPAX ROW H.ARM (m) LHPAX RHPAX 01 9.475 2 2 15 20.416 3 3 02 10.440 2 2 16 21.204 3 3 OA 03 11.405 2 2 17 21.991 3 3 04 12.390 3 3 18 22.779 3 3 05 13.177 3 3 19 23.566 3 3 06 13.965 3 3 20 24.353 3 3 07 14.752 3 3 21 25.141 3 3 08 15.540 3 3 22 25.928 3 3 09 16.327 3 3 23 26.716 3 3 10 17.191 3 3 24 27.503 3 3 11 18.054 3 3 25 28.290 3 3 12 18.842 3 3 26 29.078 3 3 OB 14 19.629 3 3 OC 27 29.865 3 3 OA OB OC Referring to 2.4 ∆Index for passenger boarding determine. H OA =10.44 m H OB =16.39 m H OC =25.53 m FORWARD INACCURACY Considering the following loading scenario C. BALANCE CHART DESIGN 152 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G Inaccuracy for cabin OA E cabin OA distribution fwd = W pax in cabin OA fwd x (H-arm pax in cabin OA fwd – H-arm OA ) W pax in cabin OA fwd = 8 x Pax average weight = 8 x 84 = 672 kg weight average Pax 8 weight average Pax 2 H weight average Pax 2 H weight average Pax 4 H arm - H row3 row2 row1 fwd OA cabin in pax × ×× × × ×× × × ×× × + ++ + × ×× × × ×× × + ++ + × ×× × × ×× × = == = 10.2m 84 8 84 2 11.405 84 2 10.44 84 4 9.475 arm - H fwd OA cabin in pax = == = × ×× × × ×× × × ×× × + ++ + × ×× × × ×× × + ++ + × ×× × × ×× × = == = E cabin OA distribution fwd = 672 x (10.2 – 10.44) = – 161.28 kg.m Inaccuracy for cabin OB E cabin OB distribution fwd = W pax in cabin OB fwd x (H-arm pax in cabin OB fwd – H-arm OB ) W pax in cabin OB fwd = 34 x Pax average weight = 34 x 84 = 2856 kg H-arm pax in cabin OB fwd = 15.37 m E cabin OB distribution fwd = 2856 x (15.37 – 16.39) = – 2913.12 kg.m Inaccuracy for cabin OC E cabin OC distribution fwd = W pax in cabin OC fwd x (H-arm pax in cabin OC fwd – H-arm OC ) W pax in cabin OC fwd = 36 x Pax average weight = 36 x 84 = 3024 kg H-arm pax in cabin OC fwd = 24.35 m E cabin OC distribution fwd = 3024 x (24.35 – 25.53) = – 3568.32 kg.m Total inaccuracy for all the cabins m 4620.64kg. 3568.32² 2931.12² 161.23² E fwd n distibutio passenger − −− − = == = + ++ + + ++ + − −− − = == = C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 153 W E I G H T A N D B A L A N C E E N G I N E E R I N G b) Inaccuracy on the passengers’ weight On the balance chart the passenger influence is taken into account as a delta index per passenger cabin section (CABIN OA, CABIN OB, …), this delta index is based on an average passenger weight for the corresponding cabin section. Now the real loading may have a total weight different from the one determined using average weight. This difference will generate an inaccuracy on the aircraft CG determination. This inaccuracy is named passenger weight inaccuracy. • Passenger weight inaccuracy The real passenger weight is W pax real = W pax average ± ∆W pax W pax average and ∆W pax are determined in relation with the statistical survey used to determine the passenger weight. Pax weight Nb of pax Pax average Weight µ µµ µ Standard Deviation σ σσ σ W pax average = µ and ∆W pax = 3σ, the 3σ value is chosen to ensure that W pax average covers 99,73 % of the population. For each cabin section used on the balance chart we have W pax real OX = W pax average OX ± ∆W pax OX W pax real OX = W pax average x (number of pax in OX) ± ∆W pax OX ∆W pax OX is determined considering that each individual passenger weight inaccuracy is independent from the weight inaccuracy of the other passengers. 2 paxn 2 pax2 2 pax1 pax n ∆W ... ∆W ∆W ∆W + ++ + + ++ + + ++ + = == = The inaccuracy is the same for each individual passenger and equals 3σ. n 3σ ) (3 n ∆W 2 npax = == = × ×× × = == = σ σσ σ • Impact of pax weight inaccuracy on aircraft CG determination E passenger weight = ± ∆W passenger x (H-arm ∆Wpassenger - H-arm limit ) The passenger weight inaccuracy is determined for each cabin section that is represented on the balance chart. E cabinXX weight = ± ∆W passengers in cabin XX x (H-arm cabin XX - H-arm limit ) The inaccuracy in weight is maximum when the cabin section is full of passengers so sectionXX in passengers of number maximum 3σ ∆W XX cabin in passengers = == = Then the total inaccuracy is determined considering each cabin section inaccuracy independent from the other ones. ... + E + E + E E fwd OC Cabin 2 fwd OB Cabin 2 fwd OA Cabin 2 fwd weight passenger − −− − = == = ... + E + E + E E aft OC Cabin 2 aft OB Cabin 2 aft OA Cabin 2 aft weight passenger + ++ + = == = C. BALANCE CHART DESIGN 154 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Ex : A320 forward inaccuracy with the above example cabin layout Referring to 2.4 ∆Index for passenger boarding determine. H OA =10.44 m for 12 passengers H OB =16.39 m for 66 passengers H OC =25.53 m for 72 passengers Passenger average weight = 84 kg and corresponding standard deviation = 15 kg. The forward limit CG of the A320 is between 15% (18.43 m) and 17% (18.51 m) for aircraft weight between minimum weight and 73 500 kg. Cabin OA : E cabinOA weight = ± ∆W passengers in cabin OA x (H-arm cabin OA - H-arm limit ) H OA =10.44 m is forward for the limit so a positive ∆W passengers in cabin OA may cause the CG move out of the limit. The more conservative E cabinOA weight is obtained for H-arm limit = 18.51 m 1258kg.m 18.51) (10.44 12 15 3 E ight cabinOA we − −− − = == = − −− − × ×× × × ×× × = == = Cabin OB : E cabinOB weight = ± ∆W passengers in cabin OB x (H-arm cabin OB - H-arm limit ) H OB =16.39 m is forward for the limit so a positive ∆W passengers in cabin OB may cause the CG move out of the limit. The more conservative E cabinOB weight is obtained for H-arm limit = 18.51 m 755kg.m 18.51) (16.39 66 15 3 E weight cabinOC − −− − = == = − −− − × ×× × × ×× × = == = Cabin OC : E cabinOC weight = ± ∆W passengers in cabin OC x (H-arm cabin OC - H-arm limit ) H OC =25.53 m is aft for the limit so a negative ∆W passengers in cabin OC may cause the CG move out of the limit. The more conservative E cabinOC weight is obtained for H-arm limit = 18.43 m 2711kg.m 18.43) (25.53 72 15 3 - E ight cabinOA we − −− − = == = − −− − × ×× × × ×× × = == = Total inaccuracy for all the cabins 3082kg.m 2711² 755² 1258² E fwd weight passenge − −− − = == = + ++ + + ++ + − −− − = == = C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 155 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.4.3. Inaccuracy on fuel loading on board the aircraft a) Inaccuracy on the fuel location On the balance chart the fuel influence is taken into account as a delta index per total fuel quantity, this delta index is based on a fuel H-arm for the corresponding fuel weight. Now the fuel H-arm depends on the fuel volume contained in each tank and this volume is linked to the fuel weight through the fuel density. So an inaccuracy on fuel density will generate an inaccuracy on the fuel H-arm and consequently on the aircraft CG determination. In addition the Zero Fuel limit design is based on the theoretical fuel vector at a chosen density (usually 0.785 kg/l). This Zero Fuel limit is used to ensure that flight CG all along the flight and landing CG before landing are within their own operational limits. As a standard density value is used for the Zero Fuel limit determination it is necessary to take into account the possible differences on actual aircraft CG due to density impact. This inaccuracy is named fuel density inaccuracy. Note : Fuel density is also called fuel specific gravity, in this document the word density will be used. • Fuel density inaccuracy 1. Inaccuracy on the fuel ∆index determination. Fuel index table can be available for one single fuel density (usually for single aisle aircraft) or for a discrete range of fuel densities (for aircraft equipped with a trim tank). On single aisle aircraft (A318/A319/A320/A321, A319 corporate jet excluded), total fuel quantity is around 20 tons, consequently the fuel density variation does not lead to huge fuel quantity variation, furthermore the fuel tanks position is close to the Reference Chord. That is why fuel index table is established at a single reference density (usually 0.785 kg/l). As the fuel density can be assumed to vary between 0.76 kg/l and 0.83 kg/l, the maximum forward and aft ∆index between the reference fuel index table and the fuel index values determined at extreme fuel densities must be included into the fuel allowance. • Ex : A320-200 35 40 45 50 55 60 65 70 30 40 50 60 70 W E I G H T ( 5 t o n s t e p ) INDEX Max aft error Max fwd error Difference between 0,76 and 0,785 kg/l fuel vectors is negligible 0,76 kg/l 0,785 kg/l 0,83 kg/l C. BALANCE CHART DESIGN 156 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G On long range aircraft (A330/A340), wide-body aircraft (A300/A310) and single aisle aircraft equipped with ACTs the total fuel quantity reaches higher values and the fuel tanks may far from the Reference Chord (specially Trim Tank and ACTs). Consequently, a fuel density variation can imply a significant ∆index variation for a given weight value. That is why, fuel index tables are usually established for a discrete range of fuel densities. Actual density of the day can be an intermediate density and an interpolation will be required to get the fuel ∆index. To cover interpolation potential error, half of the maximum forward and aft index variation between two consecutive fuel densities has to be included into the fuel allowance. • Ex : A330-200 DENSITY (kg/l) WEIGHT (kg) 0,760 0,765 0,770 0,775 0,780 0,785 0,790 0,795 0,800 0,805 0,810 0,815 0,820 0,825 0,830 000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 26000 ... 87000 89000 91000 93000 95000 97000 99000 101000 103000 105000 107000 109000 111000 113000 115000 –2 –4 –6 –8 –8 –4 +1 +1 –1 –3 –5 –6 –8 …. +2 +1 +0 –1 –2 –2 –3 –4 –6 –8 –2 –4 –6 –8 –8 –4 +1 +1 –1 –3 –4 –6 –8 …. +2 +1 +0 –1 –2 –2 –3 –4 –6 –7 –2 –4 –6 –8 –8 –4 +1 +1 –1 –2 –4 –6 –8 … +2 +1 +0 –1 –1 –2 –3 –4 –5 –7 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. +2 +1 +0 +0 –1 –2 –3 –4 –5 –6 –8 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. +2 +1 +1 +0 –1 –2 –3 –4 –5 –6 –8 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. +2 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –8 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –7 …. +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –8 –10 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –7 … +3 +2 +1 +0 –1 –2 –3 –4 –4 –5 –6 –8 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –5 –7 … +3 +2 +1 +0 –1 –2 –3 –3 –4 –5 –6 –8 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –3 –5 –7 … +3 +2 +1 +0 –1 –2 –2 –3 –4 –5 –6 –7 –9 –10 –2 –4 –6 –8 –8 –4 +1 +3 +1 –1 –3 –5 –7 … +3 +2 +1 +0 –1 –1 –2 –3 –4 –5 –6 –7 –8 –10 –2 –4 –6 –8 –8 –4 +1 +3 +1 –1 –3 –5 –7 … +4 +3 +2 +1 +0 +0 –1 –2 –3 –4 –5 –6 –7 –8 –10 –2 –4 –6 –8 –8 –4 +1 +3 +1 –1 –3 –5 –7 … +3 +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –8 –9 –11 FULL –9 –9 –9 –9 –9 –9 –9 –9 –9 –10 –10 –10 –10 –10 –10 2. Inaccuracy on the Zero fuel limit design The Zero Fuel limit design process (see related chapter “Zero fuel limit determination”) uses a reference fuel vector that is leaned on operational flight and landing operational limits. As actual fuel vector may be different from the reference one (due to a different fuel density), flight and landing operational allowances have to include an additional margin covering the zero fuel limit design. To do so, maximum forward and aft index variation at critical points (because they are the points used in the zero fuel limit design) between the reference fuel vector and the extreme fuel vectors have to be included into the fuel allowance. Maximum fwd and aft index difference between two consecutives fuel densities: 1 i.u Consequently, to cover interpolation, a 0.5 i.u fwd and aft margin will be included into the fuel allowance. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 157 W E I G H T A N D B A L A N C E E N G I N E E R I N G b) Inaccuracy on the fuel weight On the balance chart the fuel influence is taken into account as a delta index per total fuel quantity which is the sum of the delta indexes per individual tanks. For each tank the fuel quantity is known with a certain accuracy. This inaccuracy is linked to the Fuel Quantity Indicator (FQI) system inaccuracy whatever the flight phase an inaccuracy needs to be taken into account. This difference between estimated and real fuel weight per tank will generate an inaccuracy on the aircraft CG determination. This inaccuracy is named fuel weight inaccuracy. • Fuel weight inaccuracy The real fuel weight is W fuel real = W fuel estimated ± ∆W fuel For each tank, the inaccuracy is ±1% of the tank capacity, plus ±1% of the actual fuel quantity in the tank. ∆W fuel tank n = ±1% Total_weight tank n ± 1% Actual_weight tank n Note : if one tank is empty the ∆W fuel tank is considered nil. Note : These figures are conservative ones (refer to Aircraft Maintenance Manual section 28-42- 00). Each tank quantity is independent from the other tanks’ one. Such a weight deviation per tank has an impact on the actual fuel vector shape, some points of the vector being shifted forward or aft. Some points are more critical than others: those points corresponding to a fuel quantity for which ± ∆W fuel may cause the aircraft CG be shifted out of the certified limits. There are called critical points. Critical points are defined phase per phase, one being critical for the forward certified limit and another for the aft certified limit. They are determined leaning the fuel vector on the aircraft certified limits, indeed throughout the whole fuel vector the aircraft CG must remain in the limits. C. BALANCE CHART DESIGN 158 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G • Ex: A330-200 aircraft with FCMC stage 9.0 Takeoff phase - Forward critical point: The forward critical point for the takeoff phase is defined as the contact point between fuel vector and forward takeoff certified limit corresponding to the highest fuel quantity, the whole fuel vector between the critical point and fuel = 0 kg remaining inside flight and landing limits. 110000 120000 130000 140000 150000 160000 170000 180000 190000 200000 210000 220000 230000 240000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 WEIGHT INDEX Takeoff Flight Landing Forward Takeoff critical point 36 500 kg - Aft critical point: 110000 120000 130000 140000 150000 160000 170000 180000 190000 200000 210000 220000 230000 240000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 WEIGHT INDEX Takeoff Flight Landing Aft Takeoff critical point 42 900 kg The aft critical point for the takeoff phase is defined as the forward one but with respect to the aft takeoff envelope. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 159 W E I G H T A N D B A L A N C E E N G I N E E R I N G In flight phase - Forward critical point: The forward critical point for the flight phase is defined as the contact point between fuel vector and forward flight certified limit, the whole fuel vector between the critical point and fuel = 0 kg being inside the flight certified limit. The fuel vector can be during flight outside the landing certified limit because of in-flight movements (pax and cabin attendants movements) that slightly modify aircraft CG compared to static situations (takeoff and landing). 110000 120000 130000 140000 150000 160000 170000 180000 190000 200000 210000 220000 230000 240000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 WEIGHT INDEX Takeoff Flight Landing Forward Flight critical point 36 500 kg - Aft critical point: The aft critical point for the flight phase is defined as the forward one but with respect to the aft flight limits. 110000 120000 130000 140000 150000 160000 170000 180000 190000 200000 210000 220000 230000 240000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 WEIGHT INDEX Takeoff Flight Landing Aft Flight critical point 38 900 kg C. BALANCE CHART DESIGN 160 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G Landing phase - Forward critical point: The forward critical point for the landing phase is defined as the contact point between landing fuel vector and forward landing certified limit, the whole landing fuel vector between the critical point and fuel = 0 kg remaining inside the landing limit and the associated flight fuel vector remaining inside the flight envelope. 110000 120000 130000 140000 150000 160000 170000 180000 190000 200000 210000 220000 230000 240000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 WEIGHT INDEX Takeoff Flight Landing Forward Landing critical point 36 500 kg - Aft critical point: The aft critical point for the landing phase is defined as the forward one but with respect to the aft landing envelope. 110000 120000 130000 140000 150000 160000 170000 180000 190000 200000 210000 220000 230000 240000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 WEIGHT INDEX Takeoff Flight Landing Aft Landing critical point 14 730 kg Fuel Weight inaccuracy (E fuel weight ) is determined for the fuel quantity corresponding to the critical point. And it is calculated for each individual tank. E fuel weight = ± ∆W fuel x (H-arm ∆Wfuel - H-arm limit ) Then the total inaccuracy is determined considering each fuel tank weight inaccuracy independent from the other ones. ... + E + E + E E fwd tank Center 2 fwd tanks Outer 2 fwd tanks Inner 2 fwd weight fuel − −− − = == = ... + E + E + E E aft tank Center 2 aft tank Outer 2 aft tank Inner 2 aft weight fuel + ++ + = == = C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 161 W E I G H T A N D B A L A N C E E N G I N E E R I N G c) Total fuel inaccuracy The final fuel allowance includes the three above mentioned inaccuracies: − Fuel weight inaccuracy linked to FQI inaccuracy (all flight phases) − Inaccuracy on the fuel ∆index determination. (takeoff phase) − Inaccuracy on the Zero fuel limit design (flight and landing phase only in case of non takeoff protected Zero Fuel limit and on all three phases in case of takeoff protected Zero Fuel limit) Then the total inaccuracy is determined considering each inaccuracy independent from the other ones. C. BALANCE CHART DESIGN 162 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.5. Inaccuracy due to CG computation method The balance chart used to determine the aircraft CG position can be : − graphical − tabulated − computerized In each case the computation is based on − a sum of weights = DOW + Payload Weight +Fuel Weight − a sum of index = DOI + Payload ∆Index +Fuel ∆Index Each weight of the sum is rounded to the closest unit value. Each index and ∆index of the sum may be rounded to : − the closest index unit in the case of paper systems (graphical or tabulated) − the closest decimal (tenth or hundredth) in the case of computerized systems. The weight sum is then considered to be precise and no inaccuracy is taken into account. Depending of the rounding system of the index and on the method to determine the index value for each weight value, an index inaccuracy has to be taken into account. Note1 : the computerized systems rounded to the tenth or hundredth, are considered usually to be precise enough not to take into account any inaccuracy. Note2 : some computerized systems may be based directly on each item H-arm value and not on the item ∆index, in this case the computation is usually much more precise (without pre- computation) and no inaccuracy is considered. The index inaccuracy is first determined analyzing the balance chart as a number of index units. The value of the inaccuracy in term of moment depends on the index formula chosen. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 163 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.5.1. Tabulated balance chart inaccuracy On the tabulated balance chart the ∆index value for each item loaded is read in an index table. There are two methods to define index tables : − Tables with constant step in index − Tables with constant step in weight. a) Tables with constant step in index Those tables are usually used for passengers and cargo ∆index for fuel ∆index tables with constant step in weight are used. CARGO n CARGO n Weight (kg) ∆index Weight (kg) ∆index 203 +1 0 - 203 +0 611 +2 204 - 611 +1 1018 +3 612 - 1018 +2 1426 +4 1019 - 1426 +3 1833 +5 1427 - 1833 +4 CARGO n Weight (kg) ∆index 0 +0 204 +1 612 +2 1019 +3 1427 +4 Building this type of table consists of determining the transition weights for which there is a step between one index value and the other. In the above example : − For weight between 0 and 203 kg the ∆index value varies between 0 and 0.49… − For weight between 204 and 611 kg the ∆index value varies between 0.5 and 1.49… − … Note : The same examples apply for passenger ∆index table except that the weight is replaced by the number of passengers. In those tables the user selects the ∆index corresponding to the weight or passenger number range he is considering. For each weight range the ∆index range is 1 index value. So selecting the rounded figure the user generates an maximum inaccuracy of ±0.5 index unit in each table. The inaccuracy due to one table is independent from the inaccuracies due to the other tables so : table index cargo5 2 table index cargo4 2 table index cargo3 2 table index cargo2 2 table index cargo1 2 tables index cargo E + E + E + E + E E ± ±± ± = == = K + E + E + E E table index OC cabin 2 table index OB cabin 2 table index OA cabin 2 tables index passenger ± ±± ± = == = C. BALANCE CHART DESIGN 164 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G b) Tables with constant step in index Those tables are usually used for fuel ∆index or for all ∆index tables in the balance chart. DENSITY (kg/l) WEIGHT (kg) 0.785 3000 4000 5000 6000 7000 8000 +2 +1 +0 –2 –4 –7 In those tables the user selects the ∆index corresponding to the weight or passenger number he is considering. For a weight value not presented in the table different solutions are available : − interpolation allowed : the user finds the ∆index by interpolating between the 2 closest ∆index values. Ex: for weight of 6500 kg the ∆index is –3. In this case the maximum inaccuracy value is reached for the maximum range of ∆index between two weights and the inaccuracy value equals half the ∆index range. Ex: in the above table the maximum ∆index range is between 7000 kg and 8000 kg and corresponds to a maximum inaccuracy in index of ±1.5 index units. − interpolation is not recommended by the operator procedure, the user always retains the value corresponding to the lowest (highest) weight. Ex: for weight of 6500 kg the ∆index is –2 (–4). In this case the maximum inaccuracy value is reached for the maximum range of ∆index between two weights and the inaccuracy value equals the ∆index range. Ex: in the above table the maximum ∆index range is between 7000 kg and 8000 kg and corresponds to a maximum inaccuracy in index of ±3 index units. The inaccuracy due to one table is independent from the inaccuracies due to the other tables so : table index cargo5 2 table index cargo4 2 table index cargo3 2 table index cargo2 2 table index cargo1 2 tables index cargo E + E + E + E + E E ± ±± ± = == = K + E + E + E E table index OC cabin 2 table index OB cabin 2 table index OA cabin 2 tables index passenger ± ±± ± = == = C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 165 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.5.2. Graphical balance chart inaccuracy On the graphical balance chart the ∆index value for each item loaded is read on a diagram. On this diagram the ∆index is drawn manually on each line for each item loaded. The manual drawing generates an inaccuracy due to the drawing precision as illustrated below : the blue line being the ideal drawing and the red line a manual drawing. The inaccuracy due to this manual input is highly dependant on the index scale readability on the balance chart and the index scale is linked to the choice of index formula C constant. AIRBUS standard constants are determined in order to have a major step in index length drawn on the chart between 1 and 1.5 cm, each major step is divided into 10 minor steps so one minor step length is between 1 and 1.5 mm. Then the cargo weight steps and passenger number steps on the diagram are determined so that between two oblique lines on the scale there is no more than 5mm to ensure sufficient accuracy when interpolating. Following these design rules it is assumed that on each scale the maximum inaccuracy is of 0.5 index unit. The inaccuracy due to one scale is independent from the inaccuracies due to the other scales so : table index cargo5 2 table index cargo4 2 table index cargo3 2 table index cargo2 2 table index cargo1 2 tables index cargo E + E + E + E + E E ± ±± ± = == = K + E + E + E E table index OC cabin 2 table index OB cabin 2 table index OA cabin 2 tables index passenger ± ±± ± = == = C. BALANCE CHART DESIGN 166 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.5.3. example on A330 graphical balance chart On this balance chart the final CG is determined − entering the Dry Operating Index in the initial scale. − determining ∆index for each cargo compartment (5 scales) − determining ∆index for each cabin section (3 scales) − determining the fuel ∆index in the fuel index table (inaccuracy depends on the weight step in the table, and on the procedure interpolation/no interpolation) in this example inaccuracy = 2 index units. − entering the fuel index in the fuel scale Each inaccuracy scale is independent from the other ones. unit index 2.55 E 2 0.5 10 0.5 2 0.5 3 0.5 5 0.5 E E + E + E 3 + E 5 + E E method ion determinat CG 2 2 2 2 2 2 2 method ion determinat CG scale fuel 2 table fuel 2 scale section Cabin 2 scale Cargo 2 scale inital 2 method ion determinat CG ± ±± ± = == = + ++ + × ×× × ± ±± ± = == = + ++ + + ++ + × ×× × + ++ + × ×× × + ++ + ± ±± ± = == = × ×× × × ×× × ± ±± ± = == = 2500 Moment C Moment ∆Index = == = = == = E CG determination method = ±2.55 index units = ± 2.55 x 2500 = ± 6374 kg.m. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 167 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.6. Item movements during flight impacting the aircraft CG position Aircraft CG positions computed on the balance chart are based on DOW and DOCG values. DOW and DOCG values are published for the following configuration : − Flaps/slats in clean position − Landing Gear extended − Reversers in retracted position − Water in potable water tanks. This configuration corresponds to the aircraft configuration used at aircraft weighing. Note : the above mentioned configuration at DOW is the most common one, some operators may use a different configuration. In this case the below presented method has to be adapted. Note : on all the aircraft the movement of the reversers is considered negligible in term of CG movements so they are no more considered below. The computed aircraft CG positions during the flight are computed for a given configuration in the cabin, passengers and crew seated in Takeoff/Landing configuration and trolleys locked in the galleys. During the flight, passengers and crew members move together with the trolleys, these movements generate a shift of the aircraft CG position. These differences in aircraft configuration have to be taken into account when checking the CG position against the relevant certified CG limits, introducing an additional moment in the operational margin. E aircraft CG movement = Real Aircraft Moment – Balance Chart Aircraft Moment E aircraft CG movement = Moment due to item movement Item being : Flaps/Slats, Landing Gear, Revesers, Water, Passenger, Crew… C. BALANCE CHART DESIGN 168 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.6.1. Flaps/Slats and Landing gear movements DOCG F/S clean LDG down Estimated LDCG F/S clean LDG down Estimated TOCG F/S clean LDG down Estimated Flight CG F/S clean LDG down DOCG F/S clean LDG down LDCG F/S extented LDG down Flight CG F/S clean LDG up TOCG F/S extended LDG down DOW and DOCG values are published for the following configuration : − Flaps/slats in clean position − Landing Gear extended So on the balance chart all the aircraft CG values correspond to this configuration. In reality Takeoff configuration is Flaps/slats extended, Landing configuration is Flaps/slats extended and Flight configuration is landing gear retracted. E aircraft CG movement = Moment due to Flaps/Slats or Landing Gears movement The moments generated by Flaps/Slats and Landing Gears movement are published in the WBM in section 1.00. Flaps extension moves the aircraft CG aft, Slats extension moves it forward, the total resulting moment for takeoff and landing possible configuration moves it aft so the real takeoff and landing CG will always be aft of the estimated value. So for aft certified CG operational margins determination the maximum aft movement has to be taken into account to prevent the aircraft CG being out of the limits. For the forward certified CG operational margins determination, there is no risk of being out of the limits as the operational configurations will always lead to a more aft CG than the estimated one. Nevertheless it is possible to take benefit of this situation by taking into account this CG movement is reducing the forward operational margin. Landing gears retraction moves the aircraft CG forward so the real in flight CG will always be forward of the estimated value. So for forward certified CG operational margins determination the maximum forward movement has to be taken into account to prevent the aircraft CG being out of the limits. For the aft certified CG operational margins determination, there is no risk of being out of the limits as the operational configurations will always lead to a more forward CG than the estimated one. Nevertheless it is possible to take benefit of this situation by taking into account this CG movement is reducing the aft operational margin. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 169 W E I G H T A N D B A L A N C E E N G I N E E R I N G • ex : A330-200 Flaps and Slats movements : Takeoff configuration : the possible configurations are CONF 1+F, CONF 2, CONF 3. Impact on forward operational limit : E aircraft CG movement = 0 kg.m or E CONF 1+F Impact on aft operational limit : E aircraft CG movement = E CONF 3 = + 368 kg.m Landing configuration : the possible configurations are CONF 3, CONF FULL. Impact on forward operational limit : E aircraft CG movement = 0 kg.m or E CONF 3 Impact on aft operational limit : E aircraft CG movement = E CONF FULL = + 476 kg.m Landing Gears movements : Flight configuration : Nose and Main landing gears retracted Impact on forward operational limit : E aircraft CG movement = E Main + E Nose = - 6677 kg.m Impact on aft operational limit : E aircraft CG movement = 0 kg.m or E Main gear + E Nose gear C. BALANCE CHART DESIGN 170 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.6.2. Water movement from potable to waste tank DOCG Water in Potable water tanks Estimated LDCG Water in Potable water tanks Estimated TOCG Water in Potable water tanks Estimated Flight CG Water in Potable water tanks DOCG Water in Potable water tanks LDCG Water in waste tanks Flight CG Water moving between potable tanks and waste tanks DOW and DOCG values are published for the following configuration : − Water is located in the potable water tanks. So on the balance chart all the aircraft CG values correspond to this configuration. In reality at landing part of the water is located in the waste tanks and part of the water has been ejected out of the aircraft. E aircraft CG movement = Moment due to item movement = Moment due to water movement from potable tanks to waste tanks + Moment due to water ejection. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 171 W E I G H T A N D B A L A N C E E N G I N E E R I N G E aircraft CG movement = W Water in waste tank x (H-arm final position – H-arm initial location ) + W Water ejected x (H-arm final position – H-arm initial location ). E aircraft CG movement = W Water in waste tank (H-arm waste tank – H-arm potable water tank ) - W Water ejected x H-arm potable water tank . Position of the different tanks in the aircraft are published in WBM 1.30 • ex : A330-200 Takeoff configuration 700 kg of water in the potable water tanks. Landing configuration : - 1/3 of the water ejected out of the aircraft, - 2/3 of the water in the waste tank. E aircraft CG movement = W Water in waste tank (H-arm waste tank – H-arm potable water tank ) - W Water ejected x H-arm potable water tank . | || | . .. . | || | \ \\ \ | || | + ++ + × ×× × × ×× × − −− − | || | . .. . | || | \ \\ \ | || | + ++ + − −− − + ++ + × ×× × × ×× × = == = 2 51.691 39.167 700 3 1 2 51.691 39.167 2 52.369 52.587 700 3 2 E movement CG aircraft E aircraft CG movement = 3289.53 – 10600.1 = - 7310.57 kg.m C. BALANCE CHART DESIGN 172 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.6.3. In flight passenger and crew movements DOCG Flight CG Passengers and crew moving On the balance chart all the aircraft CG values are based on the passenger and crew position at takeoff. We consider that at landing the configuration is identical to the takeoff one. During the flight passengers and crew are moving throughout the cabin. E aircraft CG movement item = Moment due to item movement E aircraft CG movement item = W item x (H-arm Item final position – H-arm Item initial location ) The estimation of the possible inflight movements depends on the airline operations, on the cabin layout, on the flight type… The objective is to determine realistic impact on the aircraft CG during the flight by considering the different periods of the flight when there are movements in the cabin : − Meal servicing, − Passengers moving to the lavatories − Crew moving to the crew rest areas − Duty free sells − … Some of these movements may happen simultaneously, some will move the aircraft CG forward, some will move it aft. A standard movement scenario is used in Airbus standard method : − All movements are defined based on initial position of the item or person at takeoff. − Galleys, lavatories and crew are assigned per passenger class, and movements are performed within each class section. − All movement in one direction (forward/aft) happen simultaneously. − There is one passenger per lavatory, when 2 lavatories are available for the same passenger section then 2 passengers from the middle of the section move toward them at the same time. − There is one cabin crew and one trolley per aisle for meal servicing. − When underfloor crew rest or crew rest area is defined in the cabin, then additional movements towards the rest area are taken into account. Crew members form the whole cabin are moving. − Additional movement may be added : cabin crew to the cockpit, cockpit crew to cabin area. This scenario enables to establish for each item or person moving E aircraft CG movement item = W item x (H-arm Item final position – H-arm Item initial location ), then as all movement in one direction (forward/aft) happen simultaneously, the total E aircraft CG movement is the sum of each individual E aircraft CG movement item. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 173 W E I G H T A N D B A L A N C E E N G I N E E R I N G • ex : A330-200 movements forward G5 G6 G1 G2 G 3 G 4 G5 G6 La Lb Ld Lc Le Lg Lf Cabin attendant 2 B class pax from row 4 to La and Lb 2 Eco class pax from row 21 to Lc and Ld 2 trolleys from G5/G6 to pax row 18 2 cabin crew from aft positions to pax row 18 1 cabin crew from forward position to cockpit Forward movements are split into 3 movements for each movement E aircraft CG movement item = W item x (H-arm Item final position – H-arm Item initial location ) needs to be determined. W item depends on the operator assumptions, passenger or crew member weights are defined without hand luggage. Eg : for average pax weight = 84 kg, the pax weight considered for the movement is (average pax weight – hand baggage weight) = 84-9 = 75 kg. H-arm Item final position and H-arm Item initial location are published in the weight and balance manual in the 1.40 and 1.50 sections. 1. passenger movements : 2 business class passengers to business class lavatories E aircraft CG movement 2 pax from row 4 to La/Lb = W 2 pax x (H-arm La/Lb – H-arm Row4 ) a b c d E aircraft CG movement 2 pax from row 4 to La/Lb = 2x 75 x (10.755 – 16.933) = - 926.7 kg.m C. BALANCE CHART DESIGN 174 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 2 economy class passengers to economy class lavatories E aircraft CG movement 2 pax from row 21 to Lc/Ld = W 2 pax x (H-arm Lc/Ld – H-arm Row21 ) E aircraft CG movement 2 pax from row 21 to Lc/Ld = 2x 75 x (19.627 – 33.360) = - 2059.95 kg.m 2. Trolley movements 2 trolleys from G5/G6 to passenger row 18 E aircraft CG movement 2 trolleys from G5/G6 to row 18 = W 2 trolleys x (H-arm Row 18 – H-arm G5/G6 ) E aircraft CG movement 2 trolleys from G5/G6 to row 18 = 2 x 80 x (30.77–54.064) = - 3727.04 kg.m 3. Crew members movements 2 cabin crew from aft positions to passenger row 18 E aircraft CG movement 2 cabin crew from aft position to row18 = W 2 cabin crew x (H-arm Row18 – H-arm aft ) E aircraft CG movement 2 cabin crew from aft position to row18 = 2x70 x (30.77–55.21) = -3421.6 kg.m 1 cabin crew from forward position to cockpit E aircraft CG movement 1 cabin crew from fwd position to cockpit = W 1 cabin crew x (H-arm cockpit – H-arm fwd ) E aircraft CG movement 1 cabin crew from fwd position to cockpit = 70 x (8.872–11.575) = -189.21 kg.m Total forward movements : E aircraft FWD CG movement = E aircraft CG movement 2 pax from row 4 to La/Lb + E aircraft CG movement 2 pax from row 21 to Lc/Ld + E aircraft CG movement 2 trolleys from G5/G6 to row 18 + E aircraft CG movement 2 cabin crew from aft position to row18 + E aircraft CG movement 1 cabin crew from fwd position to cockpit E aircraft FWD CG movement = - (926.7 + 2059.95 + 3727.04 + 3421.6 + 189.21) = - 10320.5 kg.m C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 175 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.7. Total operational margins determination The total operational margins per flight phase are determined summing each individual margin, some of them being considered as systematic, the other ones as non systematic. Aircraft CG affected OPERATIONAL MARGIN Systematic / Non systematic TO LD IF Inaccuracy on initial data (DOW and DOCG) Non Syst X X X Inaccuracy on items loading on board the aircraft (passengers, cargo, fuel) Inaccuracy on the passengers’ location Non Syst X X X Passenger loading Inaccuracy on the passengers’ weight Non Syst X X X Inaccuracy on the cargo location Non Syst X X X Cargo loading Inaccuracy on the cargo weight Non Syst X X X Inaccuracy on the fuel location Non Syst X X X Fuel loading Inaccuracy on the fuel weight Non Syst X X X Inaccuracy due to CG computation method Manual balance chart Non Syst X X X Computerized balance chart Item movements during flight impacting the aircraft CG position Flaps/Slats movements Syst X X Landing gear movements Syst X Water movement from potable to waste tank Syst X In flight passenger and crew movements Syst X n Systematic 1 Systematic 2 n Systematic NON 2 1 Systematic NON phase1 flight FWDmargin ... FWDmargin FWDmargin ... FWDmargin margin FWD + ++ + + ++ + + ++ + + ++ + + ++ + − −− − = == = n Systematic 1 Systematic 2 n Systematic NON 2 1 Systematic NON phase1 flight AFTmargin ... AFTmargin AFTmargin ... AFTmargin margin AFT + ++ + + ++ + + ++ + + ++ + + ++ + + ++ + = == = C. BALANCE CHART DESIGN 176 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.8. Takeoff, Landing, In-Flight operational limits determination When total operational margins per flight phase are determined they are applied to each corresponding certified limit to obtain the operational limits per flight phase. Certified limits are published in the WBM 1.10 tables presenting A/c Certified Weight = W and A/c Certified CG limit (%RC) = CG. Certified limits Flight phase Weight W CG (%RC) CG certified CG (H-arm) H-arm certified Aircraft Moment on certified limit W CG 100 CG MAC LEMAC × ×× × × ×× × 100 CG MAC LEMAC W × ×× × × ×× × × ×× × Total operational margin Flight phase = E Operational limits Flight phase Weight W Aircraft Moment on operational limit CG (H-arm) H-arm operational CG (%RC) CG operational W W x H-arm certified - E W E - arm - H x W certified MAC 100 LEMAC W E arm H W certified × ×× × | || | . .. . | || | \ \\ \ | || | − −− − − −− − − −− − × ×× × • ex : A320-200 Takeoff forward operational limits determination Certified limit Operational limit Weight W kg CG certified %RC H-arm certified m Moment kg.m Operational margin kg.m Moment kg.m H-arm operational m CG operationa l %RC 37320 15 18.431 686 168 691 465 18.573 18.393 53000 15 18.431 976 818 982 114 18.530 17.383 63000 17 18.514 1 166 406 1 171 703 18.598 19.005 72000 17 18.514 1 333 036 1 338 333 18.588 18.754 73500 18.9 18.594 1 366 664 - 5 296.33 1 371 961 18.666 20.618 15% 17% 19% 21% Operational margin Moment W e i g h t Certified forward limit Operational forward limit H-arm Certified = (CG Certified x 0.041935) + 17.8015 Moment Certified = H-arm Certified x Weight Moment 0perational = Moment Certified – (- 5 296.33) H-arm operational = Moment 0perational / Weight CG operational = (H arm operational – 17.8015) / 0.041935 The complete computation leads to the determination of each individual operational limit. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 177 W E I G H T A N D B A L A N C E E N G I N E E R I N G In Flight limits Takeoff limits Landing limits Operational Limits On the balance chart the 3 operational limits – Takeoff, Landing and In-flight – are not represented because if the Takeoff CG position check against its corresponding limit can be done after a manual or computerized computation, the determination of the Landing CG and furthermore the In-flight CG positions on a paper document is much more difficult, it is hardly possible to check these CG positions against their corresponding CG limits. So only a Takeoff limit is drawn on the Load and Trim Sheet, this takeoff limit is the more limiting one of the three operational limits, depending on the values of each operational margins. Note often on A320 documents the forward In Flight limit is more limiting than the Takeoff one. And this specially for low aircraft weights. So the forward operational limit published on the balance chart or in the AHM560 is made of part of the In Flight limit and part of the Takeoff limit. C. BALANCE CHART DESIGN 178 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.9. Zero Fuel limit determination 3.9.1. Definition of the Zero Fuel Limit On the balance chart it is necessary to check the Takeoff CG position against the Takeoff operational limit, this ensures that the aircraft CG position is within the certified takeoff limit. Nevertheless this check is not sufficient to ensure that the aircraft CG remains within the in flight and landing limits during the whole flight. This second check cannot be made easily by checking the landing CG position and the different flight CG positions because of the difficulty to estimate these values. To perform this check an additional limit has been introduced : the Zero Fuel Limit. The Zero Fuel limit is determined to ensure that during the whole flight and at landing the aircraft CG remains within the limits. 3.9.2. Zero Fuel limit computation method Two different methods are used to determine the Zero Fuel limit, depending on procedure applied on the balance chart. a) Zero fuel limit takeoff protected : − IF Zero fuel CG is within the Zero fuel limit − And IF takeoff weight and landing weight are compliant with the operational takeoff and landing maximum weights. THEN Takeoff, Landing and In Flight CG are within the allowed limits using the whole flight. With this type of limit, assuming that the takeoff and landing weight limitations are checked on the AHM516 (Load Message) the only check to be performed on the balance chart is to ensure that the Zero Fuel CG position is within the Zero Fuel limit. b) Zero fuel limit not takeoff protected : − IF Zero fuel CG is within the Zero fuel limit − IF Takeoff CG is within the Takeoff operational limit − And IF takeoff weight and landing weight are compliant with the operational takeoff and landing maximum weights. THEN Takeoff, Landing and In Flight CG are within the allowed limits using the whole flight. With this type of limit, assuming that the takeoff and landing weight limitations are checked on the AHM516 (Load Message) the check to be performed on the balance chart is to ensure that the Zero Fuel and Takeoff CG position are within the Zero Fuel and Takeoff operational limits. c) Computation method : For each type of Zero Fuel limit the calculation principle is the same, it consists in : − Determining the possible aircraft CG position at Takeoff, Landing and Flight provided the Zero Fuel CG position is known, by analyzing the fuel vectors applicable to each flight phase. (refer to Fuel System Chapter). − Using the fuel vectors, determining all the allowed Zero Fuel CG positions so that all possible takeoff (for takeoff protected limit), landing and in flight CGs remains within their operational limits from no fuel to maximum fuel quantity. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 179 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.9.3. Zero Fuel limit computation example : A320 The computation is based on the operational limits previously determined and on the possible CG positions at takeoff, landing and in flight for a given Zero Fuel CG position, these positions are given by the different fuel vectors. For A320 family aircraft the takeoff, in flight and landing fuel vectors are identical. a) Zero fuel limit takeoff protected : Each flight phase fuel vector is leaned against the corresponding operational limit. In the case of A320 aircraft the fuel vector is leaned against the more inside operational limit. This operation is repeated for Zero Fuel weights between minimum aircraft weight and Maximum Certified Zero Fuel Weight. For this example the final result is the pink area above. Note : This area is determined for all fuel quantities between 0 to maximum fuel quantity. But if the fuel quantity is lower than maximum fuel quantity the resulting Zero Fuel limit would be larger than the one above. So some operators using the takeoff protected Zero Fuel limit may chose to have several limits presented depending on the takeoff fuel quantity. C. BALANCE CHART DESIGN 180 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G b) Zero fuel limit not takeoff protected : Landing and flight phase fuel vector are leaned against the corresponding operational limit. In the case of A320 aircraft the fuel vector is leaned against the more inside operational limit between landing and flight. The takeoff limit is not used as the takeoff CG position is supposed to be checked within the operator procedure. On the forward limit, the final part of the vector, which corresponds to the center tank refueling or consumption, is not taken into account (it goes out of the operational limits on the graph). This optimization is made to enlarge as much as possible the Zero Fuel limit. It is possible because the takeoff CG position is checked and because the fuel burn in the center tank shifts the aircraft CG aft. So it ensures that if the takeoff CG is within of the takeoff operational limit then the other CG positions will remain in the limits also during the whole flight. This operation is repeated for Zero Fuel weights between minimum aircraft weight and Maximum Certified Zero Fuel Weight For this example the final result is the pink area above. Note : In this case the Zero Fuel limit is optimized and there is no need to have different limits for different fuel quantities. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 181 W E I G H T A N D B A L A N C E E N G I N E E R I N G 4. BALANCE CHART DRAWING PRINCIPLE A balance chart is made of several parts – the ∆index scales or tables and the operational limits graph. The aim of this chapter is to explain the way to draw the different parts. LOAD and TRIM SHEET A330-243 VERSION : 18 BC-264 YC DRY OPERATING WEIGHT CONDITIONS WEIGHT (kg) H-arm (m) I = (H-arm - 33.1555) x W 5000 + 100 DRY OPERATING WEIGHT INDEX AIRCRAFT REGISTER : DATE : PREPARED BY : FLT Nbr : CAPT. SIGNATURE : FROM : TO : DRY OPERATING WEIGHT WEIGHT DEVIATION (PANTRY) ± CORRECTED DRY OPERATING WEIGHT = CARGO + PASSENGERS + ZERO FUEL WEIGHT = TOTAL FUEL ONBOARD + TAKEOFF WEIGHT = ZONES E F G H WEIGHT DEVIATION (kg) BASIC INDEX CORRECTION ZONES DRY OPERAT. WEIGHT DEVIATION E F G H +300 kg -1.30 -0.82 +1.22 -300 kg +1.30 +0.82 -1.22 INDEX CORRECTION CORRECTED INDEX ALL WEIGHTS IN KILOGRAMS ZONES Nbr WEIGHT(kg) CARGO1 500 kg CARGO2 500 kg CARGO3 500 kg CARGO4 500 kg CARGO5 250 kg CABIN OA 10 PAX CABIN OB 40 PAX CABIN OC 15 PAX 70 80 90 100 110 120 130 140 INDEX FUEL INDEX - INDEX + SEE TABLE OVERLEAF NOTES TAKEOFF CG% MAC ZFW CDU INPUT WEIGHT (kg x 1000) AIRCRAFT CG % MAC 70 80 90 100 110 120 130 140 INDEX 110 120 130 140 150 160 170 180 190 200 210 220 230 A irc ra ft W e ig h t (k g x 1 0 0 0 ) 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 Aircraft CG (%MAC) OPERATIONAL LIMITS TAKEOFF ZFW MTOW = 230000 kg MLW = 180000 kg MZFW = 168000 kg 18 20 22 24 26 28 30 32 34 36 38 40 7 6 5 4 3 2 1 0 %MAC PITCH TRIM Constant Constant Nose Down Nose Up . . . x 8 4 = INDEX CORRECTION ZONES E F G PAX OA (18 PAX) ROW 1 TO 3 OB (152 PAX) ROW 12 TO 31 OC (112 PAX) ROW 32 TO 46 CARGO 1 2 3 4 5 (3468 kg) (18869 kg) (15241 kg) 1 1 1 2 2 2 3 3 3 A A G1 G1c Ln 12 12 12 14 14 14 15 15 15 16 16 16 17 17 17 18 18 18 19 19 19 20 20 20 21 21 21 22 22 22 23 23 23 24 24 24 25 25 25 26 26 26 27 27 27 28 28 28 29 29 29 30 30 30 31 31 31 32 32 32 33 33 33 34 34 34 35 35 35 36 36 36 37 37 37 38 38 38 39 39 39 40 40 40 41 41 41 42 42 42 43 43 43 44 44 44 45 45 45 46 46 A A A A A A A A G2 G3 G5 G6 G7 Lh1 Lk1 Lk2 Lh2 Lp Lo C. BALANCE CHART DESIGN 182 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.1. ∆ ∆∆ ∆index scales or tables for loaded items 4.1.1. Graphical balance chart On the graphical balance chart the ∆index value for each item loaded – passenger or cargo – is read on a diagram. One scale per cargo compartment and one scale per passenger cabin section are represented. The scales are made of oblique lines, with distance between 2 lines representing the ∆index corresponding to the individual cargo weight or passenger number, usually presented on the right end of each scale. The oblique lines have been introduced in order to ease the manual drawing on the document. Indeed the first possibility is to have vertical lines but is it difficult to determine the end point of the drawing. XX pax ∆Index Pitch XXX kg Whereas with oblique line the horizontal and vertical lines can be more easily drawn. XX pax ∆Index Pitch XXX kg To draw the pitch between two line use the ∆index(1 kg) value. C ) H arm (H (1kg) ∆Index Ref item item − −− − − −− − = == = and determine the ∆index(XXX kg) or ∆index(XX PAX) needed on the balance chart. Note 1 : the horizontal distance between the oblique line top and bottom points represents exactly ∆index(XXX kg) or ∆index(XX PAX) on the index scale. Note 2 : the oblique line orientation : from top right to bottom left in case of forward CG movement, and from top left to bottom right in case of aft CG movement when loading the item must be strictly applied, because of the habits taken when manually using a balance chart. A change in the orientation may lead to misusing of the document. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 183 W E I G H T A N D B A L A N C E E N G I N E E R I N G Note 3 : the fuel loading ∆index used to be drawn on similar scales for some specific aircraft, nevertheless today due to the complexity of the refuel vectors and the high impact of fuel density on the fuel vector, this graphical method is no more used for Airbus aircraft. 4.1.2. Tabulated balance chart a) Tables with constant step in index Those tables are usually used for passengers and cargo ∆index for fuel ∆index tables with constant step in weight are used. CARGO n CARGO n Weight (kg) ∆index Weight (kg) ∆index 203 +1 0 - 203 +0 611 +2 204 - 611 +1 1018 +3 612 - 1018 +2 1426 +4 1019 - 1426 +3 1833 +5 1427 - 1833 +4 CARGO n Weight (kg) ∆index 0 +0 204 +1 612 +2 1019 +3 1427 +4 Building this type of table consists of determining the transition weights for which there is a step between one index value and the other. In the above example : − For weight between 0 and 203 kg the ∆index value varies between 0 and 0.49… − For weight between 204 and 611 kg the ∆index value varies between 0.5 and 1.49… − … b) Tables with constant step in weight Those tables are usually used for fuel ∆index or for all ∆index tables in the balance chart. DENSITY (kg/l) WEIGHT (kg) 0.785 3000 4000 5000 6000 7000 8000 +2 +1 +0 –2 –4 –7 Building this type of table consists of determining the ∆index(XXX kg) and rounding it to the closest unit or closest tenth, depending on the airline procedure. C. BALANCE CHART DESIGN 184 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 4.2. Operational limits diagram The operational limits are represented on a diagram − on X-axis the aircraft index values − on Y-axis the aircraft weight values Then iso-CG lines are represented to enable the user to determine finally the aircraft CG position value in %RC. It is based on the index formula expressed in %RC. K MAC C Ref%) - (%RC Weight Index + ++ + × ×× × × ×× × = == = With: C and K constants depending on the aircraft type MAC = Mean Aerodynamic Chord of the aircraft. • For CG = Ref% then K MAC C Ref%) - (Ref% Weight Index + ++ + × ×× × × ×× × = == = Index = K, whatever the weight value. Therefore the Ref% the iso-CG line is a straight line associated to index = K. Ref % Weight Index = K Index C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 185 W E I G H T A N D B A L A N C E E N G I N E E R I N G • For other CG values then: The index values corresponding to two weights W 1 and W 2 are linked by the iso-CG line. K MAC C Ref%) - (CG W Index a 1 1 + ++ + × ×× × = == = and K MAC C Ref%) - (CG W Index a 2 2 + ++ + × ×× × = == = Ref % Weight Index = K Index Ref+1 Ref+2 Ref+3 Ref+4 Ref-3 Ref-2 Ref-1 When the diagram is prepared the operational limits can be drawn on it : − “takeoff” operational limit (the limit resulting from the operational margins computation and the selection of the more limiting part between takeoff, landing and in flight operational limits) − zero fuel operational limit. C. BALANCE CHART DESIGN 186 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 5. THE AHM560 The AHM560 is a standardized IATA document containing weight and trimming data necessary for both the aircraft CG position and the operational limits calculations. The computerized balance chart systems (EDP systems) are based on the data provided in the AHM560. Part of this document contains the results from the balance chart design process, other information is linked to operators’ needs in term of EDP system computation and EDP system output. A specific AHM560 should be used by airlines for each type of aircraft they have, information given in the AHM560 can be applied to several aircraft registrations, provided those aircraft have the same Weight & Balance characteristics (same weight variants, same certified limits, same cabin layout, etc.). 5.1. Generalities The AHM560 is divided into four main parts: − PART A: COMMUNICATION ADDRESSES − PART B: GENERAL INFORMATION − PART C: AIRCRAFT DATA − PART D: LOAD PLANNING DATA Each part is divided into several Sheets, that correspond to different types of data. The aircraft type, the airline code and the part and sheet number of each page are written in the header as follows: 5.2. PART A: COMMUNICATION ADDRESSES This part provides with the handling agents' and the carrier' addresses. It also lists all the documents that need to be produced by the EDP system. The supplemental documents are for instance a Loadsheet, a Loading Instruction/Report, a NOTOC, a LDM, a CPM, … C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 187 W E I G H T A N D B A L A N C E E N G I N E E R I N G 5.3. PART B: GENERAL INFORMATION Part B is a summary of weight data used by the airline : passenger weights (Male / Female / Children / Infants), crew weights and cabin baggage weights, as well as the list of items taken into account for the Dry Operating Weight (DOW) and Dry Operating Index (DOI) calculation. 5.4. PART C: AIRCRAFT DATA This part contains the aircraft detailed list for which the document is applicable with the aircraft definition in term of weights and index and all the trimming data. 5.4.1. C Sheet 1 C Sheet 1 contains the information the operator needs to be shown on the EDP system Loadsheet output and the way the operator has chosen to determine the passenger loading influence on aircraft CG position. 5.4.2. C Sheet 2 C Sheet 2 contains the aircraft list for which the document is applicable and their definition in term of Dry Operating Weight or Basic Weight. C. BALANCE CHART DESIGN 188 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 5.4.3. C Sheet 3 C Sheet 3 is a reminder of the index formula used for index calculation, with the exact values of constants and aircraft data that enter in this formula. At the bottom of this sheet, the stabilizer trim setting is given in function of the MAC value at takeoff. 5.4.4. C Sheet 4 C Sheet 4 contains the fuel index tables, there may be only one fuel table for the standard fuel density used by the operator of several tables for a range of densities. Note : for all aircraft equipped with a trim tank it is recommended to issue several tables for different densities. 5.4.5. C Sheet 5 C Sheet 5 gives the ∆index to be used to determine the influence of items or persons in the cockpit. 5.4.6. C Sheet 6 C Sheet 6 contains the aircraft list for which the document is applicable (same list as in C Sheet 2) and their definition in term of maximum weights. 5.4.7. C Sheet 7 C Sheet 7 contains the operational limits to be used for CG checks in the EDP system. − “takeoff” operational limit (the limit resulting from the operational margins computation and the selection of the more limiting part between takeoff, landing and in flight operational limits) − zero fuel operational limit. C. BALANCE CHART DESIGN Getting to Grips with Aircraft Weight and Balance 189 W E I G H T A N D B A L A N C E E N G I N E E R I N G 5.4.8. C Sheet 8, 9, 10 C Sheet 8 details the cabin sections defined by the operator to determine the passenger loading influence per section. C Sheet 9 gives the ∆index to be used to determine the influence of passenger loading per cabin section. C Sheet 10 gives the ∆index to be used to determine the influence of passenger loading per seat row. It also enables to indicate the type of seat used in the cabin. 5.4.9. C Sheet 11, 12 C Sheet 11 and 12 gives the ∆index to be used to determine the influence of any cabin crew, any item in the galleys and any pantry. 5.4.10. C Sheet 13, 14 C Sheet 13 gives the ∆index to be used to determine the influence of cargo loading per cargo compartment. C Sheet 14 gives the ∆index to be used to determine the influence of cargo loading per cargo position. 5.4.11. C Sheet 15 C Sheet 15 details the operator’s procedure for ballast carriage. 5.5. PART D: LOAD PLANNING DATA This part is composed of sheets to enter general miscellaneous information such as the ideal trim line data in D Sheet 1, details about ULD (containers and pallets) in D Sheet 2, and regulations about special loads transportation in D Sheet 3. D. LOAD AND TRIM SHEET SOFTWARE Getting to Grips with Aircraft Weight and Balance 191 W E I G H T A N D B A L A N C E E N G I N E E R I N G D. LOAD AND TRIM SHEET SOFTWARE 1. INTRODUCTION The Load and Trim sheet software enables the Airbus operators to produce a load and trim sheet and its associated AHM560, AHM516 and AHM515 documents for any Airbus model: A319, A320, A321, A300, A310, A330 and A340 except for freighter and combi aircraft. These loading and trimming documents are generated from the weight and balance characteristics of the aircraft supplied in a database, from the assumptions set by the user and from the cabin arrangement defined for the aircraft. This software allows the Airbus operators to quickly produce and update these documents following any aircraft modification affecting the certified limits, the passenger distribution, the cargo distribution or the fuel management. The LTS software enables also to produce specific data files that are used by the Weight&Balance module of the Less Paper Cockpit package. 2. OBJECTIVES The main objectives of this software are the electronic distribution and update of the Weight&Balance data of Airbus aircraft and the calculation and creation of the loading and trimming documents. This software allows: − To improve access time to the information. − To ensure technical data accuracy − To propose a user-friendly interface to visualize and update the Weight & Balance data. − To perform the error calculation required for the operational envelopes determination. − To reduce the production time of the loading and trimming documents. D. LOAD AND TRIM SHEET SOFTWARE 192 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3. SOFTWARE DESCRIPTION First of all, the LTS program uses a database containing a complete set of assumptions and data. The program structure relies on a relational database that stores the following pieces of information: − The weight and balance data for all the MSN of the operator. These data will be updated and sent to the operator by Airbus at each aircraft modification affecting the loading and trimming. − The Airbus default settings and the user’s personal settings for various parameters such as the index formula, the passengers’ average weights… − The cabin layout data. The loading and trimming documents are generated for any aircraft of the user’s fleet. The selection of the relevant aircraft is performed at the interface initialization. The interface of the LTS program allows the user to perform with several tasks described below. 3.1. Unit system: It is possible to select the unit system either metric or US system. 3.2. Aircraft modifications: It is possible to consult the aircraft modifications validated for the aircraft chosen. The modifications enumerate the weight variant certified for the aircraft, the cargo configuration, the fuel system installed on the aircraft… D. LOAD AND TRIM SHEET SOFTWARE Getting to Grips with Aircraft Weight and Balance 193 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.3. Aircraft configurations: Through the Aircraft Configuration frame, the user can: − Set the index formula. − Define the average weights for the passengers, crew and trolley. − Consult the tanks’ characteristics and the fuel management curve. − Consult and update the cargo holds’ characteristics. The update function enables to take into account the modifications that can be carried out in the cargo holds: installation of a new cargo system, installation of an ACT (Auxiliary Center Tank) or an UCRC (Under Crew Rest Container)… For instance, for the A320 family, the program can select any of the available cargo options: Bulk, CLS (Cargo Loading System), CLS and Occasional Bulk… − Consult and update the certified design weights and the certified design CG limits. The update function allows to select a new weight variant and/or a new certified CG envelope that has been approved in the Aircraft Flight Manual. D. LOAD AND TRIM SHEET SOFTWARE 194 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.4. Cabin layout: Through the cabin layout frame, the user can visualize or create a cabin layout thanks to a graphical interface. The cabin layout describes all the main deck’s characteristics that affect the aircraft CG position: passenger seats, cabin attendant seats, lavatories, galleys and the aircraft section. Some specific functions allow to create quickly a new cabin layout: utilization of the pitch, copy of the seats when the left and the right side of the cabin are identical. With those users entries and with the aircraft data, the LTS carries out the following tasks: − Calculation of the influence of passengers, cargo and fuel loading on the aircraft weight and CG position. − Calculation of the operational margins (to consider the different errors and assumptions made during a CG determination). − Productions of the Load and Trim sheet and of the AHM 050 document. Moreover, additional possibilities are also offered: − Calculation and production of a Load and Trim sheet for training flights (non- commercial flights). − Production of data files for the LPC Weight&Balance module (see paragraph “Less Paper in the Cockpit” in part D). − Saving and storage of documents for history and follow-up. D. LOAD AND TRIM SHEET SOFTWARE Getting to Grips with Aircraft Weight and Balance 195 W E I G H T A N D B A L A N C E E N G I N E E R I N G 3.5. Operational margins customization The LTS software enables to customize certain assumptions used for the operational margins. − DOW weight used for initial data inaccuracy determination − Passenger weight standard deviation − In flight cabin movements. Some inaccuracy sources may be canceled such as − Passenger distribution − Cargo distribution − Inaccuracy due to CG computation method These inaccuracies may be canceled in case of CG determination using an EDP system. D. LOAD AND TRIM SHEET SOFTWARE 196 Getting to Grips with Aircraft Weight and Balance W E I G H T A N D B A L A N C E E N G I N E E R I N G LOADING OPERATIONS A. Loading Generalities.............................................................. 201 1. Load control...................................................................................................................... 201 1.1. Loading constraints.................................................................................................... 201 1.2. Load control organization and responsibilities............................................................ 201 1.3. Load control qualification............................................................................................ 204 2. Aircraft Weight .................................................................................................................. 205 2.1. Regulation.................................................................................................................. 205 2.2. Aircraft Weighing........................................................................................................ 206 3. Passenger weight ............................................................................................................. 207 3.1. General ...................................................................................................................... 207 3.2. Survey........................................................................................................................ 207 4. Loading Operations .......................................................................................................... 210 4.1. Preparation before loading......................................................................................... 210 4.2. Opening/Closing the doors......................................................................................... 215 4.3. On loading ................................................................................................................. 216 4.4. Off loading ................................................................................................................. 217 5. Loading Limitations........................................................................................................... 218 5.1. Structural limitations and floor panel limitations.......................................................... 218 5.2. Stability on ground – Tipping...................................................................................... 223 6. Securing of loads.............................................................................................................. 225 6.1. Introduction................................................................................................................ 225 6.2. Aircraft acceleration ................................................................................................... 225 6.3. Tie-down computation................................................................................................ 227 B. Special Loading ..................................................................... 241 1. Live animals and perishable goods................................................................................... 241 1.1. Generalities................................................................................................................ 241 1.2. Live animals transportation ........................................................................................ 243 1.3. Perishable goods ....................................................................................................... 246 2. Dangerous goods ............................................................................................................. 249 2.1. Responsibility............................................................................................................. 249 2.2. References................................................................................................................. 249 2.3. Definitions.................................................................................................................. 249 2.4. Identification............................................................................................................... 250 2.5. Classification.............................................................................................................. 250 2.6. Packing...................................................................................................................... 254 2.7. Marking and labeling.................................................................................................. 255 2.8. Documents................................................................................................................. 256 2.9. Handling and loading ................................................................................................. 258 2.10. Special shipments.................................................................................................... 259 Getting to Grips with Aircraft Weight and Balance 197 L O A D I N G O P E R A T I O N S LOADING OPERATIONS C. Operational Loading Documents........................................... 263 1. Load and volume information codes ................................................................................. 263 1.1. Load Information Codes............................................................................................. 263 1.2. ULD Load volume codes............................................................................................ 263 1.3. Codes used for loads requiring special attention........................................................ 264 2. Loading Instruction / Report (LIR)..................................................................................... 265 2.1. Introduction 265 2.2. Manual LIR 266 2.3. EDP LIR..................................................................................................................... 269 3. Container/Pallet distribution message (CPM) ................................................................... 271 4. Loadsheet......................................................................................................................... 273 4.1. Introduction................................................................................................................ 273 4.2. Manual loadsheet....................................................................................................... 274 4.3. EDP Loadsheet.......................................................................................................... 278 4.4. ACARS loadsheet ...................................................................................................... 279 5. Balance calculation methods............................................................................................ 280 5.1. Introduction................................................................................................................ 280 5.2. Manual balance calculation method ........................................................................... 280 5.3. EDP balance calculation methods 288 A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 199 L O A D I N G O P E R A T I O N S LOADING GENERALITIES INTRODUCTION During aircraft preparation before a flight the aircraft loading process is one of the key steps, which must follow some strict rules to ensure passenger, loads and aircraft safety and security. The following chapter details the loading constraints and the necessary organization to fulfil them. The first step before ensuring the aircraft loading is correct is to determine with the necessary accuracy the empty aircraft weight and corresponding CG position, then the determination of the average passenger weight is also important for the loaded aircraft weight determination. Air transport is not more risky than other ways of transport. Indeed, air journey, with no vibration, shunting or bumping shocks, is probably the smoothest method of carrying cargo. Air transport has another advantage that can be very useful for cargo such as perishable goods or live animals: its rapidity. To ensure an adequate loading and a safe air transport, it is necessary to prepare the shipment. The shipment must be checked and pre-packed before loading. Aircraft have a flexible structure. In addition to their natural contortion in flight, the quantity and distribution of load transported have an influence on the fuselage deformation. Therefore, Airbus has defined structural loading limitations that the operator must respect. These limitations are certified by airworthiness authorities. Detailed definitions of these limitations are proposed in this chapter. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 201 L O A D I N G O P E R A T I O N S A. LOADING GENERALITIES 1. LOAD CONTROL 1.1. Loading constraints The main constraints an airline has to face for loading are the following: − Safety must be insured during the whole flight whatever goods are transported. − Short time for loading: airlines want to have the aircraft ground time as short as possible in order to respect schedules if an operational irregularity occurred and to make more profit increasing the aircraft utilization. − The whole shipment must arrive in good condition at destination airport, particularly special goods such as dangerous goods, perishable cargo and live animals. − Loading and unloading must be done at the right place: any mistake concerning the location of the shipment in the aircraft or, above all, its destination could engender extra expenses and be very detrimental to the image of the airline. To meet the above objectives and in the interest of flight safety, airlines have to set up an organization for an efficient load control and ensure a high level of proficiency of all staff engaged in load control work. Recommendations are provided in IATA AHM part 590. 1.2. Load control organization and responsibilities Load control is a procedure ensuring that: − Aircraft center of gravity will remain within limits during the whole flight − Aircraft weight limitations are not exceeded − Aircraft is loaded in accordance with the airline’s regulation − Information on the loadsheet reflects the actual load on the aircraft A few years ago, airlines used to issue manual loadsheets. Nowadays, EDP (Electronic Data Processing) systems are widely used, leading to different working organizations. Nevertheless, responsibilities inside the organization remain comparable. A. LOADING GENERALITIES 202 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 1.2.1. Manual loadsheet The load control organization shall be based, at every station, on three functions to ensure the compatibility of all figures on the loadsheet with the actual loading of the aircraft: a) Function 1 : Load planner and loadsheet agent / Load controller / D1 … The main task of this agent is to issue loading instructions (LIR) for people in charge of the loading, according to the information collected from the passenger and cargo departments, and then to prepare the loadsheet. The responsibilities of the load planner are to: − Collect all data relating to the load for a specific flight (Cargo, baggage, mail, transit load from incoming LDM/CPM) − Plan load for total flight and ensure that hold capacities and different limitations are not exceeded and center of gravity remains within limits − Plan special loads according to restrictions, maximum quantities, separation and segregation requirements − Consider the effect of the center of gravity on fuel consumption − Issue the Loading Instruction Report (LIR) The loadsheet agent has to prepare the loadsheet. The main tasks are to: − Collect the relevant Dry Operating Weight / Index of the aircraft − Fill out the number of passengers according to booking information − Transfer the Loading Information (LIR) into the loadsheet. − Collect estimated fuel figures from the dispatch and fill out the loadsheet − Enter the transit load data from incoming loadmessage (LDM) − Ensure that the total traffic load does not exceed the allowed traffic load − Ensure that the center of gravity will not exceed the operational limits b) Function 2 : Loading supervisor / loading agent / C2 … (Ramp handling) The loading supervisor carries out the aircraft loading or supervises the aircraft loading when it is subcontracted to a handling company. He must ensure that the loading is done in accordance with the LIR, and after completion, confirms the loading or advise the Load control Supervisor or loadsheet agent of any deviation from the initial loading instruction (Loading Report). The loading supervisor is responsible for the following tasks. He has to: − Obtain the Loading Information (LIR) − Assemble the load and necessary equipment − Off-load disembarking deadload and dispatch it as fast as possible − Ensure ULD’s are serviceable and secure − Ensure ULD’s are correctly tagged − Ensure correct lashing and spreading − Check that dangerous goods are correctly stowed − Check that security lockers procedures are followed − Confirm the loading or advise the Load controller / Loadsheet agent of any deviation from the Loading Instructions − Sign the Loading Report (LIR) A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 203 L O A D I N G O P E R A T I O N S c) Function 3 : Load control supervisor / Dispatcher / Red cap / D3 … The Load control supervisor is the responsible agent for the check of the loadsheet against the final loading report, fueling order and actual number of passengers in the cabin. He has to organize as well the turnaround and is in contact with the crew. The main responsibilities of the Load control supervisor are to: − Inform all parties of the aircraft position and estimated time of arrival on ramp − Check that the loading agent received the LIR and that relevant equipment is correctly planned and positioned − Ensure availability of passenger handling equipment − Ensure that passenger handling personnel is briefed − Confirm passenger boarding time with the authorities − Ensure liaison with crews, both cockpit and cabin − Collect the Loading Report (LIR) from the loading supervisor, and check the loading is in accordance with the LIR − Collect final fuel information from the fueling order − Establish the final loadsheet: ) Update number of passengers according to passenger boarding information at the gate ) Enter exact deadload from the Loading Report (LIR) ) Enter exact amount of fuel from the fueling order ) Ensure that the total traffic load does not exceed the allowed traffic load ) Ensure that the center of gravity will not exceed the operational limits ) Enter last minute changes and inform the flight crew ) Sign the loadsheet and give a copy to the crew (or send it by ACARS) − Check that aircraft documents are on board (Loadsheet, Trim sheet, NOTOC) − Release the aircraft − Send the LDM/CPM to the next station (Loadmessage/Cargo Pallet message) − Store documents in the station’s flight file These three functions must be performed by at least two agents to minimize the risk of mistake and ensure a high safety level. The same person can cumulate, as an example, function 1 and function 3. A. LOADING GENERALITIES 204 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 1.2.2. EDP loadsheet In case of EDP (Electronic Data Processing) loadsheet, the responsibility for correct loadsheet and trim data must be shared and clearly identified due to the various operational possibilities (decentralized input of data, decentralized loadsheet issuance, LMC…). The above three functions still exist, but can be decentralized. As an example, Load planning and loadsheet can be prepared at the airline’s base (function 1), whereas loading (function 2) and Load control supervision (function 3) is done at the station. 1.3. Load control qualification The carrier is responsible for its shipment. In order to achieve an acceptable level of standardization and proficiency, minimum requirements shall be recognized in the training of carriers or handling companies’ personnel involved in load control functions. The carrier has the responsibility to: − evaluate and approve the handling company’s training program or subject the personnel involved to a single or periodical qualification tests − Obtain a list of qualified personnel for a given aircraft type A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 205 L O A D I N G O P E R A T I O N S 2. AIRCRAFT WEIGHT 2.1. Regulation The purpose of this chapter is to present what is required by the authorities concerning aircraft weighing. The following part will present how the weighing is performed. For more detailed information on aircraft weighing please report to JAR-OPS 1 Subpart J – Mass and Balance. (Paragraph 1.605 and appendix 1 to JAR-OPS 1.605) or/and to FAA Advisory circular 120-27A. 2.1.1. General information: In order to elaborate a proper weight and balance document prior to a flight, the weight of the aircraft (as well as its center of gravity) has to be determined. This weight is first determined by the aircraft manufacturer and is found in the Weight and Balance Manual (Chapter 2.00: Weighing Report). It is the Operating Empty Weight in the Airbus weighing report, it may be named Basic Weight in some other weighing reports. From this Operating Empty Weight/Basic Weight the operator can define the aircraft Dry Operating Weight for each aircraft flight. During its operational life, the aircraft is going to be modified in different possible ways (new cabin arrangement, Service Bulletin implementation, new equipment…). These modifications are going to have an impact on the weight and the CG of the aircraft and therefore the aircraft as to be weighed on a regular basis. Moreover, the mass and the CG of each aircraft shall be re-established either by weighing or calculation (if the operator is able to provide the necessary justification to prove the validity of the method of calculation chosen), whenever: − the cumulative changes to the dry operating mass exceed ± 0·5% of the maximum landing mass − or the cumulative change in CG position exceeds 0·5% of the mean aerodynamic chord. 2.1.2. Fleet mass and CG position: The FAA and the JAA allow an operator that flies a fleet of the same type of aircraft (same model and configuration) to use an average dry operating weight and CG position for the whole fleet. However, individual aircraft weight and CG have to meet the following tolerances: − The weighed or calculated weight of the aircraft varies by less than ±0.5% of the maximum structural landing weight from the established dry operating fleet mass. − The CG position varies by less than ±0.5% of the mean aerodynamic chord from the fleet CG. If an aircraft does meet these tolerances, it has to be omitted from the fleet. However, in the case where an aircraft falls within the tolerance for the dry operating weight but is out of the CG range, it can still be operated with the fleet average mass but with an individual CG position. A. LOADING GENERALITIES 206 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S • Fleet values determination: The number of aircraft that have to be weighed varies with the number of aircraft in the operator’s fleet. If ‘n’ is the number of aircraft in the fleet using fleet values, the operator must at least weigh, in the period between two fleet weight evaluations, a certain number of aircraft defined in the Table below: Number of aircraft in the fleet Minimum number of weighing Less than 3 n 4 – 9 2 3 + n 10 or more 10 51 + n The interval between two fleet mass evaluations must not exceed 48 months and the airplanes that have not been weighed for the longest time shall be weighed in priority. 2.1.3. Individual weights: An aircraft that does not use fleet values must be weighed every 48 months. 2.2. Aircraft Weighing The weighing of the aircraft can either be done on the aircraft’s wheel or on jacks. 2.2.1. Defueling The first action prior to aircraft weighing is the defueling of the aircraft. In order to do so, the aircraft’s nose is lifted up to bring the aircraft to a zero degree pitch attitude. This is done with the help of the aircraft clinometer located in the refueling panel. Once this is done, defueling can be started. The information used is the information of the FQI. The defueling procedure prior to weighing can be found in the Weight and Balance Manual. When the fuel quantity indicated is equal to zero, this means that all the pumpaple fuel has been removed from the aircraft. Extra fuel can be removed using the water drain. Once this is done the only fuel left on board the aircraft is the undrainable fuel (for quantities, refer to the W&B Manual). Fire services have to be present during the operation and the aircraft must be earthed. 2.2.2. Inventory During the defueling of the aircraft, a complete inventory of the equipment fitted on the aircraft is carried out. This inventory is executed with a pre established check list of the equipment that are supposed to be on board the aircraft for normal operations. This checklist will be useful when calculating the Operating Empty Weight and the associated CG. The missing equipment will be added in the weighing report. 2.2.3. Weighing Weighing has to be performed in a closed hangar. Prior to the aircraft’s positioning in the hangar, the scales have to be set to zero. Once the aircraft is in position, its pitch attitude has to be precisely measured. The weighing can then be performed. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 207 L O A D I N G O P E R A T I O N S 3. PASSENGER WEIGHT 3.1. General In order to complete the Load and Trim Sheet, a standard weight for passengers had to be adopted. These values have been fixed by the authorities. In this paragraph, we will consider aircraft seating more than 30 passengers. (For more information, please refer to the appropriate regulation: JAR-OPS1.620 or FAR 121). It is important to notice that the same rules apply to passenger checked-in baggage. The standard values used in the JAR-OPS for passenger weights are the following (these weights include passenger and carry-on baggage): All flights except holiday charters 84 kg Holiday charters 76 kg Children 35 kg However, if for some reason the operator considers that the standard weights do not apply to the routes he operates, he has the possibility of setting his own standard weights. According to the JAR-OPS1 Subpart J, the procedure is the following: If an operator wishes to use standard mass values other than those contained in the table above, he must advise the Authority of his reasons and gain its approval in advance. He must also submit for approval a detailed weighing survey plan and apply the statistical analysis method given in Appendix 1 to JAR–OPS 1.620(g). After verification and approval by the Authority of the results of the weighing survey, the revised standard mass values are only applicable to that operator. The revised standard mass values can only be used in circumstances consistent with those under which the survey was conducted. Where revised standard masses exceed those in the above table, then such higher values must be used. JAR-OPS 1.620(g) 3.2. Survey The methods necessary to revise the standard weights are described in appendix 1 to JAR-OPS 1.620(g) with reference to the IEM to JAR-OPS 1.620(g) and IEM to Appendix 1 to JAR-OPS 1.620(g). The purpose of this paragraph is to give the reader a quick overview of the methods used. In order to change the standard values, the operator must conduct a survey. This survey has to follow a certain number of rules. The average mass of passengers and their hand baggage is determined by weighing random samples of passengers representative of the type of operation (frequency of flights on various routes, in/outbound flights, applicable season, seat capacity of the aircraft…) All adult revised standard mass values must be based on a male/female ratio of 80/20 in respect of all flights except holiday charters which are 50/50. It is possible to use a different male/female ratio if it is representative of the activity (refer to regulation, in particular: IEM to Appendix 1 to JAR-OPS 1.620(g): Guidance on passenger weighing surveys) A. LOADING GENERALITIES 208 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 3.2.1. Statistical Analysis Passenger weight follows a Gaussian distribution that can be studied using statistical methods. Pax weight Nb of pax Pax average Weight µ µµ µ Standard Deviation σ σσ σ The number of passengers to weigh must be of at least the greatest of: − A number of passengers calculated from a pilot sample, using normal statistical procedures and based on a relative confidence range (accuracy) of 1% for all adult (in order to find this number of passenger, a previous survey is necessary) − 2000 passengers. (for aircraft of over 40 seats) The precision of a sample estimate is calculated for 95% reliability or ‘significance’, i.e. there is a 95% probability that the true value falls within the specified confidence interval around the estimated value. This standard deviation value is also used for calculating the standard passenger mass. As a consequence, for the parameters of mass distribution, i.e. mean and standard deviation, two cases have to be distinguished: − µ, σ : the true values of the average passenger mass and standard deviation, which are unknown and which are to be estimated by weighing passenger samples. − µ’, ' σ : the ‘a priori’ estimates of the average passenger mass and the standard deviation, i.e. values resulting from an earlier survey, which are needed to determine the current sample size. The sample size can then be calculated using the following formula: 2 ' '* 100 '* * 96 . 1 ( ¸ ( ¸ ≥ µ σ r e n where: n is the number of passengers to be weighed (sample size) ' r e is the allowed relative confidence range (accuracy) for the estimate of µ by (see also equation in paragraph 3). NOTE: The allowed relative confidence range specifies the accuracy to be achieved when estimating the true mean. For example, if it is proposed to estimate the true mean to within ± 1%, then ' r e will be 1 in the above formula. 1.96 is the value from the Gaussian distribution for 95% significance level of the resulting confidence interval. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 209 L O A D I N G O P E R A T I O N S • Calculation of average mass and standard deviation. Arithmetic mean of sample: n x n j j ∑ = = 1 µ Where j x are the mass values of individual passengers (sampling units). Standard deviation: 1 2 1 _ − | . | \ | − = ∑ = n x x n j j σ 3.2.2. Accuracy of the sample mean. The accuracy (confidence range) which can be ascribed to the sample mean as an indicator of the true mean is a function of the standard deviation of the sample which has to be checked after the sample has been evaluated. This is done using the formula: µ σ * 100 * * 96 . 1 n e r = whereby r e should not exceed 1%. The result of this calculation gives the relative accuracy of the estimate of µ at the 95% significance level. This means that with 95% probability, the true average mass µ lies within the interval: n σ µ * 96 . 1 ± A. LOADING GENERALITIES 210 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 4. LOADING OPERATIONS 4.1. Preparation before loading 4.1.1. Generalities Air transport is not more risky than other ways of transport. Indeed, air journey, with no vibration, shunting or bumping shocks, is probably the smoothest method of carrying cargo. Air transport has another advantage that can be very useful for cargo such as perishable goods or live animals: its rapidity. To ensure an adequate loading and a safe air transport, it is necessary to prepare the shipment. The shipment must be checked and pre-packed before loading. 4.1.2. ULD / Bulk Airbus aircraft have different configurations of compartments: they can be loaded either with bulk or with ULDs (Unit Load Devices). The different configurations for each aircraft are described in the “Cargo systems” part of this manual. In bulk compartments, all the items are stacked without any order. Compartments equipped with the Cargo Loading System are filled with ULDs. These ULDs allow to group items into larger units, which is easier and faster to load. ULDs can be either pallets or containers. Certified containers protect the aircraft systems and structure. They are expensive and delicate units because of the materials used to make it. Non certified containers are sometimes used to take several loads into large pre-packaged units. Both pallets and containers are locked in the aircraft using latches and end-stops. Since ULDs must be pre-packed, most of the job is done before and after the flight. It allows decreasing the station time for each aircraft, which reduces the airline’s expenses. ULDs are loaded into the aircraft thanks to specialized ground equipment. 4.1.3. Packing Items should not be loaded in the aircraft if they are not properly packed. Specific packages are required for specific cargo such as live animals, dangerous goods, wet cargo, flowers, etc. Collection sacks or nets are used to facilitate handling of small items. They are called “cover bags”. Parcels that are in the same cover bag must be off-loaded at the same airport. The destination must be written on a label attached to the sack. Not all the items can be transported in collection sacks: − Radioactive loads must not be put in collection sacks because of the minimum distances imposed between two radioactive loads − Cargo and mail must not be in the same cover bag. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 211 L O A D I N G O P E R A T I O N S Each package is then packed itself into a ULD when the aircraft is equipped. For a safe cargo transport, general rules must be applied: − When packages are loaded in a container, it is necessary to visualize the whole container load before packing (nature, form, weight and strength) − Big or heavy items must be on the bottom, small, light or weak items on the top. − Leave as few spaces as possible between two items − The load must be evenly distributed in the ULD. Heavy items must not be concentrated on a small area in the center of the pallet and/or container because of the risk of dishing. − Spreader boards could be used for high density items − If the package moves in the ULD or if the load is very heavy, then the package should be tied down − Packages loaded on open pallets should be stacked so that the whole load is stable (interlocking layers). The nets retain the load. Once they are loaded, cargo pallets and containers are weighed. Their weight is then entered on the tag described hereafter. 4.1.4. Special loads Dangerous and perishable goods, live animals, valuable cargo, human remains and urgent shipments are considered as special cargo, and special requirements apply to them. Here are some rules concerning special goods transportation. ♦ Not all the dangerous goods can be transported in passenger aircraft because of the obvious risk they engender for the safety of passengers. Some dangerous goods are even forbidden for transport by air. When they are allowed for transport by air, they must be wrapped with specific packages to minimize the risk of accident and/or incident. ♦ For live animals, two rules have a very big importance: they must not be exposed to extreme temperatures and they should be loaded in the aircraft as late as possible. Ventilation and heating systems are greatly recommended. ♦ To arrive at their destination in good condition, perishable goods require specific temperatures and relative humidity that depend on the good transported. ♦ The security of valuable cargo must be ensured during the whole journey. ♦ Handling and loading of human remains must be done with respect; coffins containing human remains must be loaded in a horizontal position, never in a vertical position. Moreover, human remains must be kept far away from other shipments such as food or some animals (dogs for example). ♦ Staff concerned by transportation of special loads must be aware of the requirements of such a cargo. Thanks to labels affixed to each package, especially to packages containing special goods, loading staff is able to identify the content of the package. A. LOADING GENERALITIES 212 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 4.1.5. Incompatibilities Some shipments are particularly restrictive to transport, like dangerous goods, live animals and perishable goods. Special requirements concerning transportation of such goods are developed in other parts of this manual (refer to “DANGEROUS GOODS TRANSPORTATION” and “LIVE ANIMALS & PERISHABLE GOODS TRANSPORTATION”). The following table from IATA AHM 645 sums up the incompatibilities between different shipment types: Here are general rules that can be extracted from this document: − Dangerous goods from classes 2, 3, 4, 5 and 8 shall not be loaded in close proximity of dangerous goods from class 1 − Dangerous goods from class 7 must be separated from animals, hatching eggs and unexposed films − Live animals must be loaded in close proximity of neither foodstuffs nor human remains − Live animals and hatching eggs must not be loaded in close proximity of dry ice − Live animals should be separated from laboratory animals − Animals that are natural enemies such as cats and dogs should not be loaded in sight, sound, smell or reach of each other − Foodstuffs must not be loaded in close proximity of human remains…. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 213 L O A D I N G O P E R A T I O N S 4.1.6. Labelling, tagging Each package or collection sack is labelled to indicate the destination and the category of load it contains. Specific labels are used for special loads; labels used to indicate the presence of dangerous goods, live animals or perishable cargo are provided in the corresponding sections. Here are some codes used to identify which category a load belongs to: B → Baggage C → Cargo (including special loads) M → Mail Unit Load Devices (ULDs) must be tagged so that the loader is able to identify loads in the containers and/or pallets. The tag must be easily readable: it must be at eye level, on a fixed side of the container or on the net of the pallet. A tag must be completed, even for empty ULDs. Its shape and colors are standardized: Size: A5 (148 x 210 mm) Color: Black letters with: BAGGAGE A red slash on a white background * DANGEROUS GOODS Red hatching surrounding the tag UNSERVICEABLE UNITS Orange background OTHER LOAD White background * Whenever an ULD contains baggage, the red line must appear on the tag. A. LOADING GENERALITIES 214 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S ULD tag example SFO Airport where the ULD must be unpacked (San Francisco) Separation between NET and TARE weight mandatory when ULDs are transferred between carriers Second leg information First leg information C Presence of special loads (refer to “Operational loading documents” for the codes) 1500 100 1600 Delete the wrong word ALF2503AF ULD code CDG AF5 025 31P UA2 053 JFK 22P C = Cargo AVI Some operators use an electronic system to read ULD tags. A bar code that contains all the previous information is then shown on the form. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 215 L O A D I N G O P E R A T I O N S 4.2. Opening/Closing the doors There are two different types of cargo doors: some open manually and others automatically (hydraulically, electrically). Ground staff operates cargo doors. No special training is required for manual doors, whereas only qualified staff is allowed to open hydraulic or electric doors. Airbus provides a detailed description of the doors and the way to operate them in the Weight & Balance Manual, so that ground staff can open and close them. In presence of wind, special care must be taken before opening the doors or when the doors are already opened. The maximum wind speed allowed to have the door opened is given in the Cargo Loading System Manual. In Airbus aircraft, the forward and aft cargo compartments doors open to the outside, whereas the bulk compartment door (compartment 5) opens to the inside. No equipment must obstruct the passage of the door. Bulk Cargo door FWD or AFT Cargo door Before closing the bulk compartment door (compartment 5), it is necessary to ensure that the door protector nets are installed and secured. After on-loading and off-loading, the loading supervisor must ensure that doors are closed and secured. A. LOADING GENERALITIES 216 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 4.3. On loading 4.3.1. Bulk This way of transporting loads is used in cargo holds not equipped with a Cargo Loading System (CLS). Most Airbus types have at least one bulk compartment at the rear, named compartment 5. The bulk compartment is divided into sections thanks to nets. Before loading, it is necessary to ensure that the separation nets are properly secured. In case of failure, refer to the “Limitations” section of the Weight and Balance Manual of the aircraft to determine the weight restriction engendered by the failure. Before loading bulk load, the loading agent has to check that there is no leaking or damaged package. This check is absolutely necessary when transporting live animals or wet cargo; every leaking or damaged package must not be loaded. Moreover, the loading agent has to ensure that the floor, the walls, and the bulkhead are in good conditions. Several precautions must be taken for loading. Most of them are common with the loading of items into ULDs, but it may be useful to remind them: − Heavy items at the bottom − Use the maximum available volume − The load must be evenly distributed in the net section − Follow specific instructions shown on the labels and place the articles so that the labels are easily visible − Respect weight limitations of the aircraft given in the Weight and Balance Manual. If one limit is exceeded, use spreader boards. − If a package is likely to damage other packages (heavy item, pieces with sharp points or edges, etc.), then the package should be tied down. − Use mechanical handling aids to handle heavy items 4.3.2. Cargo Loading System (CLS) The Cargo Loading System is installed as basic in the aft and forward cargo compartments of all the Airbus aircraft except the A318, A319, A320 and A321 where it is optional. Before being loaded in the aircraft, ULDs are filled as described above. They must be cleared of snow, ice and water. The Cargo Loading System makes the loading easier for loading staff: once in the aircraft, ULDs can be either pushed into position or progressed by powered rollers. The positions where ULDs must be loaded are indicated in the Loading Instructions/Report form (refer to “Operational Loading Documents”). A few rules must be respected to load ULDs: − Each ULD must go to the position indicated by the Loading Instructions prepared by the load planner − All obstacles have to be removed (including floor locks and side restraints) to allow the ULD to go into its position, otherwise CLS latches and or ULDs could be damaged − No staff must be in front of an ULD when it is pushed or driven into position − All the stops, locks and restraints necessary to fix the ULD in position must be used. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 217 L O A D I N G O P E R A T I O N S Once all the ULDs are loaded into the aircraft, the responsible loading supervisor checks the loading. He checks that they have been loaded in compliance with the regulations and if so, he fills the Loading Report in and signs it (refer to “Operational Loading Documents”). 4.3.3. Seats Occupied by Cargo (SOC) Sometimes, when there is not enough space in the cargo holds or for some specific cargo items, small items of cargo, baggage or mail are loaded on seats in the passenger cabin provided that several constraints are respected: − Weight limitations must not be exceeded − Safety rules must be respected (not next to emergency exits, no emergency equipment obstructed, etc.) − The package must not contain liquid, live animal or smelling cargo − The package must be tied down and covered − The seat should be protected from possible damage 4.4. Off loading The items must be off-loaded in descending order of priority: 1) Baggage must always be off-loaded first, even before passengers disembark when it is possible, so that passengers are not delayed by waiting for their baggage. There is a priority between different sorts of baggage: Code Priority Description TB 1 Baggage for transfer to various connecting flights HB 1 Group of baggage (ULD) that must be transshipped to the same connecting flight HTB 1 Group of baggage (ULD) that must be transshipped to various connecting flights FB 2 First class baggage and/or priority handled baggage B 3 Baggage (no specification) 2) Cargo 3) Mail In case of a multi-sector flight, at a transit station, the load planner has to prepare off-loading instructions (LIR (1) ) from the incoming messages (CPM/LDM (1) ). Loading agents must check cargo and mail against these instructions, and any irregularity or discrepancy with the document must be reported, at transit airport loading agents have to check all that must be off-loaded is off- loaded, and that transit shipment is at the right place. An inspection of the shipment allows determining the presence of damaged or leaking packages. In case of leakage, the source must be identified and the compartment in which leaking goods were transported must be inspected for contamination. (1) Refer to “Operational loading documents” paragraph A. LOADING GENERALITIES 218 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 5. LOADING LIMITATIONS 5.1. Structural limitations and floor panel limitations 5.1.1. Introduction Aircraft have a flexible structure. In addition to their natural contortion in flight, the repartition and the quantity of load transported have an influence on the fuselage deformation. Therefore, Airbus has defined structural loading limitations that the operator must respect. These limitations are certified by airworthiness authorities and can be found in the “Limitations” section of the Weight and Balance Manual. They follow IATA AHM 513 recommendations. 5.1.2. Structural limitations a) Running (Linear) Load Limitation • Definition: The running load limitation is the maximum load acceptable on any given fuselage length of an aircraft floor. • Unit: kg/m or lb/ft L W direction flight the in piece the of Length piece the of Weight Load Running = = The length to take into account is the length of the contact points on the floor. • Example: Let’s assume a Maximum Running Load of 2000 kg/m Example 1 Running load = = 725 kg/m < 2000 kg/m Max weight = 2000 x 1.2 = 2 400 kg > 870 kg 870 1.2 Flight direction Running load not exceeded 870 kg 1.2 m Floor Example 2 Running load = = 2175 kg/m > 2000 kg/m Max weight = 2000 x 0.4 = 800 kg < 870 kg 870 0.4 Flight direction Running load exceeded 870 kg 1.2 m Floor 0.2 m 0.2 m A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 219 L O A D I N G O P E R A T I O N S b) Area load limitation • Definition: The area load limitation is the maximum load acceptable on any surface unit of an aircraft floor. It prevents the load from exceeding the capability of the aircraft structure (floor beams, floor posts, floor panels and frames). Note: The Area Load Limitation is called “Uniformly distributed load” limitation in the Airbus Weight and Balance manuals. • Unit: kg/m 2 or lb/ft 2 S W Area Contour piece the of Weight Load Area = = The contour area is the external contour of the contact points on the floor. • Example: Let’s assume a Maximum Area Load of 2000 kg/m 2 The following rectangular load is laying onto four pieces in direct contact with the floor. The surface used for the calculation of the area load is represented by the external green contour. 0.5 m Area load = = 1450 kg/m < 2000 kg/m Max weight = 2000 x 0.6 = 1 200 kg > 870 kg 870 0.6 Area load not exceeded 870 kg 1.2 m Contour area (0.6m 2 ) 0.1 m 4 contact points 0 . 1 m c) Compartment Load Limitation • Definition: The compartment load limitation is the maximum load acceptable in an entire compartment. This limitation applies to the whole load located in a given compartment. Note: The Compartment Load Limitation is called “Cumulative load” limitation in the Airbus Weight and Balance manuals and it concerns the complete forward or aft hold or the aircraft. • Unit: kg or lb A. LOADING GENERALITIES 220 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S d) Cumulative Load Limitation • Definition: The cumulative load limitation is the maximum weight that can be carried forward or aft of a given section. This limitation prevents the weight loaded in the forward and aft fuselage sections to exceed the capability of the frames and skin stringers. Note: The Cumulative Load Limitation is called “Fuselage Shear load” limitation in the Airbus Weight and Balance manuals. • Unit: kg or lb • Example: Fuselage shear load forward of frame 40. The total payload weight applied on the main deck and the lower deck forward of frame 40 must not exceed 18 tons when the ZFWCG is 24%. 24 Weight and balance manual extract A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 221 L O A D I N G O P E R A T I O N S 5.1.3. Floor panel limitations a) Contact load limitation • Definition: The contact load limitation is the maximum load acceptable in direct contact with the aircraft floor per surface unit. This limitation is used to prevent the load in direct contact with the floor from exceeding the capability of the horizontal floor panels (metal sheet, honey comb sandwich panels). Note: The Contact Load Limitation is called “Local load” limitation in the Airbus Weight and Balance manuals. • Unit: kg/m 2 or lb/ft 2 S W Area Contact piece the of Weight Load Contact = = The contact area is the surface in direct contact with the floor. • Example: Let’s assume a Maximum Contact Load of 2000 kg/m 2 The following rectangular load is laying onto two pieces in direct contact with the floor. The area used for the calculation of the contact load is represented by the green contours. 0.5 m Contact load = = 4350 kg/m > 2000 kg/m Max weight = 2000 x 0.2 = 400 kg < 870 kg 870 0.2 Contact load exceeded 870 kg 1.2 m Surface in direct contact with the floor (0.2 m²) 0.2 m 0.2 m b) Point Load Limitation • Definition: The point load limitation represents the resistance to puncture by a heavy load bearing onto a very small surface of the floor panels. Note: The Point Load Limitation is called “Walking load” in the Airbus Weight and Balance manuals. • Unit: kg/cm 2 or lb/ft 2 • Examples: To avoid floor panel punctures, the following elementary handling precautions are recommended. A. LOADING GENERALITIES 222 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S − Never lay a heavy package on an edge or a corner: − When using a pinch bar, place a floor protector device beneath the pinch bar (plank, piece of wood): 5.1.4. Spreader floor A spreader floor enables to transport loads whose weight exceeds one of the previous limitations (running load, area load or contact load). It allows increasing either the length of the piece or the area in direct contact with the floor. Example : Max running load = 500 kg/m Max area Load = 1000 kg/m 2 Max contact load = 2000 kg/m 2 Without spreader floor Running load = = 1250 kg/m Area load = = 1429 kg/m 2 Contact load = = 3125 kg/m 2 With spreader floor Running load = = 434 kg/m Area load = = 867 kg/m 2 Contact load = = 1084 kg/m 2 500 0.4 0 . 5 m 500 0.35 500 0.16 500 + 20 1.2 500 + 20 0.6 500 + 20 0.48 0 . 2 m 0.7 m 0.2 m 0.2 m 1.2 m Note: Spreader’s weight = 20 kg A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 223 L O A D I N G O P E R A T I O N S 5.2. Stability on ground – Tipping 5.2.1. Introduction During on-loading and off-loading operations, an aft center of gravity position may lead to a tail tipping of the aircraft. Therefore, specific precautions should be considered to avoid this kind of critical situation. 5.2.2. Precautions a) Load planning During load planning, the load planner must allocate a sufficient load ahead of the aircraft center of gravity, and pay a particular attention to the distribution of the transit load on multi-sector flights. b) Loading/Off-loading Loading operations should start in the forward compartment and then in the aft ones, while off- loading operations should start in the aft compartment and then the forward ones. The same sequence applies for the galleys, whereas passenger distribution must not be considered to secure ground stability. To help the operator establishing its own recommendations for loading and off-loading, the tip up CG position (max aft CG position) is provided in the limitation section of the Weight & Balance Manual (refer to the graph “Aircraft stability on wheels”). Thus, the operator can simulate different critical scenarios and evaluate the risk of tipping of its aircraft in these configurations. A. LOADING GENERALITIES 224 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S c) Maximum wind for stability on wheels Due to the large surface of the wings, the wind can affect the stability of the aircraft on ground by providing a lift force ahead of the center of gravity and as a consequence a rolling moment around the main landing gear group or the center gear if any. The following graph, provided in the limitation chapter of the weight and balance manual, enables to determine the maximum allowable wind for a given aircraft weight and center of gravity position, as shown in the example. It can help the operator establishing its own recommendations for loading and off-loading rules in windy conditions. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 225 L O A D I N G O P E R A T I O N S 6. SECURING OF LOADS 6.1. Introduction As per IATA AHM 311, all individual items of load, which by their nature, shape or density may constitute a hazard, shall be restrained. Restraint can be achieved by filling volumetrically the compartment, the net section or the ULD, or by tie-down. Note: In IATA Airport Handling Manual (AHM) Compartments, net sections and ULDs are considered to be volumetrically full when they are filled up to three-quarters (75%) of their height. Note 2 : this value is indicated as 80% of the height in Airbus Weight and Balance Manuals. Pieces weighing 150 kg or more, when loaded as bulk in compartments or net sections should always be tied down, except on single sector flights when the compartments or net section is volumetrically full. Pieces weighing 150 kg or more, when packed in certified ULDs should be individually tied-down except when the unit is volumetrically full. Note : the 150 kg figure is the value recommended in the AHM document, nevertheless each individual operator may define a lower value for Heavy Items definition. 6.2. Aircraft acceleration 6.2.1. Influence on cargo items Anytime an aircraft accelerates, decelerates or turns, forces are generated on each cargo item. As a consequence, hazardous or heavy items must be tied-down in order to prevent them from moving, damaging the structure of the aircraft or crashing other cargo loads. The force generated by the movement of the aircraft depends on the aircraft acceleration and the weight of the piece. A. LOADING GENERALITIES 226 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 6.2.2. Load factor The load factor represents the “apparent weight”, in a given direction, of an item submitted to an acceleration that can be caused by: a speed increase, a slow down, sideway movements or vertical drops. M = mass of the item W = weight of the item = M.g a X = item’s acceleration in the X direction F X = Force in the X direction = M.a = n X .M.a F Z = Force in the X direction = M.a = M.g W a = Apparent weight = n.M.g n = Load factor n X = Load factor in the X direction M F z = W = M.g F x = M.a x = n x .M.g W a = n.M.g X axis Z a x i s Therefore, if an item weighing 1000 kg is submitted to a load factor of 1.5 in a given direction, the apparent weight of this item is equivalent to the weight of an item with a mass of 1500 kg and no load factor applied. The operator has to forecast the restraint of heavy items in each direction, taking into account the maximum admissible load factors published in the limitation chapter of the weight and balance manual of each aircraft type. Each restraint must resist to the maximum apparent weight in each direction. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 227 L O A D I N G O P E R A T I O N S 6.3. Tie-down computation 6.3.1. 3.1 Tie-down equipment a) Breaking strength The breaking strength for a lashing or a tie-down fitting represents the maximum load that the item shall withstand without failure. Only equipment for which the breaking strength is ascertained should be used. b) Lashing equipment Different types of equipment can be used for lashing: nets, cables, ropes or straps. Lashing equipment must indicate permanently the maximum breaking strength, except when the restraint equipment is part of a pallet or an aircraft compartment (pallet nets and divider nets). c) tie-down fittings Airbus cargo hold floors are equipped with tie-down points enabling quick fastening of small rings only (single stud fittings). Only the tie down points which are not required for net fastening may be used for restraint of packages. The maximum breaking strength of a single stud fitting is 900 kg (2000 lb). Heavy rings (double stud fittings), can not be used for direct tie-down on the cargo floor, but for tie-down on pallet’s or container’s rims. The maximum breaking strength for a double stud fitting is 2270 kg (5000 lb). A. LOADING GENERALITIES 228 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 6.3.2. General tie-down recommendations − It is prohibited to tie-down a load with different lashing equipment (straps and ropes as an example). − Single stud fittings and ropes can be used in case of absolute necessity, when no other equipment is available, for tie-down in bulk compartments or inside containers. − Tie-down shall ensure restraint in the forward, aft, up, left and right directions. With a standard lashing, lateral tie-down is generally covered if tie-down in the forward, aft and up directions is adequately performed except for irregular shape loads and for high CG loads. − A minimum distance between two tie-down points shall be respected (generally 30 cm between two single stud fittings and 50 cm between two double stud fittings). − Each strap or rope shall make a maximum angle of 30 degrees with the direction of restraint (e.g. α Α , α F , δ, β A , β F ). α A = Floor angle (Restraint in the AFT direction) α F = Floor angle (Restraint in the FWD direction) δ L / R = Wall angle Left / Right (Restraint in the UP direction) β A L / R = Wall angle Left / Right (Restraint in the AFT direction) β F L / R = Wall angle Left / Right (Restraint in the FWD direction) FWD AFT α A α B UP LEFT RIGHT δ L δ R TOP β A/L β F/L β A/R β F/R AFT FWD UP − It is prohibited to use two ropes or straps attached to the same tie-down point and restraining the load in the same direction. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 229 L O A D I N G O P E R A T I O N S 6.3.3. Standard lashing A standard lashing consists into four straps or ropes (2 Up, 1 Forward, 1 Aft), attached to 4 tie- down points (2 on each side of the piece in the flight direction). This basic pattern solves most of the lashing problems. A security rope may be used to maintain straps in correct position and prevent them from slipping down. Security rope Tie-down point Strap or rope Flight direction 6.3.4. Forces breakdown In order to compute the number of ropes or straps needed to restrain a load, the force applied to each tie-down point in any direction must be carefully studied. For that purpose, it is necessary to consider a reference axis system (X, Y, Z) in the Forward, Left and Up directions. Tie-down point Flight direction F 2 F 1 Z Y X In the above example, two straps are attached to each tie-down point, generating two forces: the force F 1 is generated by a strap restraining the load in the forward direction, whereas the force F 2 is generated by a strap restraining the load in the up direction. A. LOADING GENERALITIES 230 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S • Forward strap: F 1 force breakdown In X direction F 1 Z Y X F 1X α αα α β ββ β F 1X = F 1 .cos(α).cos(β) In Y direction F 1 Z Y X F 1Y α αα α β ββ β β ββ β F 1Y = F 1 .cos(α).sin(β) In Z direction F 1 Z Y X F 1Z α αα α α αα α F 1Z = F 1 .sin(α) As each strap shall make a maximum angle of 30 degrees with the direction of restraint, α and β shall be less than 30º. Consequently, for a FORWARD (or AFT) strap, the minimum restraint force in each direction can be expressed as follows: F 1x = 75% F 1 F 1y = 43% F 1 F 1z = 50% F 1 A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 231 L O A D I N G O P E R A T I O N S Note : the recommended 30°between the rope or the strap with the main direction of restraint enables a high restrained force in the needed direction, indeed by increasing this angle, one decreases the weight that can be restrained by the item. Nevertheless some operators might choose even when applying the recommended 30°to perform the computation with an angle of 45°in order to take into account a margin in case one of the ropes in not correctly tied down. In this case the above force breakdown is F 1x = 50% F 1, F 1y = 50% F 1, F 1z = 70% F 1 • Up strap: F 2 force breakdown Z Y X F 2Z δ δδ δ F 2 F 2Y F 2X =0 , F 2Y = F 2 .sin(δ) , F 2Z = F 2 .cos(δ) As each strap shall make a maximum angle of 30 degrees with the direction of restraint, δ shall be less than 30º. Consequently, for an UP strap, the minimum restraint force in each direction can be expressed as follows: F 2x = 0 F 2y = 50% F 2 F 2z = 86% F 2 Note : the recommended 30°between the rope or the strap with the main direction of restraint enables a high restrained force in the needed direction, indeed by increasing this angle, one decreases the weight that can be restrained by the item. Nevertheless some operators might choose even when applying the recommended 30°to perform the computation with an angle of 45°in order to take into account a margin in case one of the ropes in not correctly tied down. In this case the above force breakdown is F 2x = 0 , F 2y = 70% F 2, F 2z = 70% F 2 Note2: When the force is applied in the forward, left or up directions, it is considered as positive. It is counted negative in the aft and right directions. A. LOADING GENERALITIES 232 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 6.3.5. Maximum load Let’s assume, as an example, a sudden deceleration of the aircraft. Without restraining system, the load would slip forward. To prevent it from moving in the forward direction, a strap is tied- down to a single stud on each side of the load, as shown below. At each tie-down point, a force F is generated in the forward direction with a magnitude proportional to the aircraft deceleration rate. In that case, the load factor in the X direction (n x ) becomes greater than 1, and the lashing equipment shall be able to restrain a load equivalent to the piece’s apparent weight: F = n x .W (with W = piece’s weight). Moreover, each tie-down point (single stud fitting) can withstand a maximum load of 900 kg. Therefore, F must be less than 900 kg. X Y Z W FWD F 1 F 2 1 2 The forces F 1 generated by the deceleration at the tie-down point number 1 can be decomposed into three components F 1x , F 1y and F 1z as shown previously. Considering a force F 1 of 900 kg, the maximum force components at tie-down point number 1 are: F 1x max = 75% F 1 = 675 kg F 1y max = 43% F 1 = 387 kg F 1z max = 50% F 1 = 450 kg 6.3.6. Ultimate load a) Example 1 Let’s assume that the previous piece is loaded in the aft cargo hold of an aircraft, COMPARTMENT 3. As shown in the following “Weight & Balance Manual” extract, the lashing must be done so as to be able to restrain any piece submitted to a load factor of 1.69 in the FORWARD direction. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 233 L O A D I N G O P E R A T I O N S Therefore, if the piece’s weight is W, the force that has to be restrained by the lashing equipment in the forward direction is : Fx = 1.69 W As shown in the previous paragraph, the maximum load that can be restrained in the forward direction by one strap fastened to two tie-down points (1 and 2) is : Maximum load = F x max = F 1x max + F 2x max = 675 kg + 675 kg = 1350 kg The Ultimate Load represents the maximum weight of a piece or a pallet that can be restrained by a lashing equipment in a given direction. In our example, the ultimate load in the forward direction is : Ultimate load = Maximum Load / Load factor Ultimate Load = 1350 / 1.69 = 798 kg Conclusion : With ONE strap restraining the load in the forward direction, the maximum piece’s weight must not exceed 798 kg due to the breaking strength of the tie-down points. b) Example 2 Let’s assume that the load is now restrained in the forward direction by two strap as shown in the next figure. Note : It is prohibited to use two straps attached to the same tie-down point and restraining the load in the same direction X Y Z W FWD F 1 F 2 1 2 F 3 3 F 4 4 Each strap is fastened to two tie-down points, creating a force of magnitude Fn at each tie-down point n. The force that has to be restrained by the lashing equipment in the forward direction is still: Fx = 1.69 x W The maximum load that can be restrained in the forward direction by two straps fastened to four tie-down points (1, 2, 3 and 4) is : Maximum load = F x max = F 1x max + F 2x max + F 3x max + F 4x max = 4 x 675 kg = 2700 kg Ultimate Load = 2700 / 1.69 = 1597 kg Conclusion: With TWO straps restraining the load in the forward direction, the maximum piece’s weight must not exceed 1597 kg due to the breaking strength of the tie-down points. A. LOADING GENERALITIES 234 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 6.3.7. Ultimate load for a standard lashing (4 straps) Let’s now consider a standard lashing composed of four straps (1 Forward, 1 Aft, 2 Up) fastened to 4 single stud fittings (see next figure). As done previously, it is possible to establish the ultimate load in each direction (Forward, Aft, Up, Left, Right). Tie-down point Flight direction Z Y X TD LF TD LA TD RF TD RA ST A ST F ST u ST u With: ST F = Strap Forward TD LF = Tie-down point Left Forward ST A = Strap Aft TD LA = Tie-down point Left Aft ST U = Strap Up TD RF = Tie-down point Right Forward TD RA = Tie-down point Right Aft a) Angles definition The force breakdown needs to be calculated for each tie-down point. So for each point the angles α and β need to be defined. F n Z Y X α αα α β ββ β TD n α : angle between the force direction and the floor. β : angle between the force direction and the forward direction. Note : for the following example we assume that each strap shall make a maximum angle of 30 degrees with the direction of restraint. A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 235 L O A D I N G O P E R A T I O N S • Left Tie Down Points Restraint UP TD LF ST U : α = 60°, β = 90° TD LA ST U : α = 60°, β = 90° Restraint FORWARD TD LF ST F : α = 30°, β = 30° Restraint AFT TD LA ST A : α = 30°, β = 150° • Right Tie Down Points Restraint UP TD RF ST U : α = 60°, β = 270° TD RA ST U : α = 60°, β = 270° Restraint FORWARD TD RF ST F : α = 30°, β = 330° Restraint AFT TD RA ST A : α = 30°, β = 210° Tie-down point Flight direction Z Y X TD LF TD LA TD RF TD RA ST A ST F ST u ST u A. LOADING GENERALITIES 236 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S b) Force breakdown Then for each tie-down point the force breakdown is : F X = F.cos(α).cos(β) F Y = F.cos(α).sin(β) F Z = F.sin(α) • Left Tie Down Points TD LF : 2 straps : 1 UP and 1 FORWARD F x UP = 0 F Y UP = 0.5 F F Z UP = 0 86 F F x FORWARD = 0.75 F F Y FORWARD = 0.43 F F Z FORWARD = 0 50 F TD LA : 2 straps : 1 UP and 1 AFT F x UP = 0 F Y UP = 0.5 F F Z UP = 0 86 F F x AFT = - 0.75 F F Y AFT = 0.43 F F Z AFT = 0 50 F • Right Tie Down Points TD RF : 2 straps : 1 UP and 1 FORWARD F x UP = 0 F Y UP = - 0.5 F F Z UP = 0 86 F F x FORWARD = 0.75 F F Y FORWARD = - 0.43 F F Z FORWARD = 0 50 F TD RA : 2 straps : 1 UP and 1 AFT F x UP = 0 F Y UP = - 0.5 F F Z UP = 0 86 F F x AFT = - 0.75 F F Y AFT = - 0.43 F F Z AFT = 0 50 F Note : F being the maximum breaking strength allowed at the tie-down point. c) Maximum load So the maximum loads in each direction are: F X FORWARD = 0.75 F + 0.75 F = 1.5 F F X AFT = - 0.75 F - 0.75 F = - 1.5 F F Y RIGHT = - 0.5 F - 0.43 F - 0.5 F - 0.43 F = - 1.86 F F Y LEFT = 0.5 F + 0.43 F + 0.5 F + 0.43 F = 1.86 F F z = 0.86 F + 0.5 F + 0.86 F + 0.5 F + 0.86 F + 0.5 F +0.86 F + 0.5 F = 5.44 F d) Ultimate load ( ¸ ( ¸ = Factor Load Load Maximum Load Ultimate So the ultimate loads in each direction are: Ultimate Load FORWARD = F X FORWARD / n FORWARD = 1.5 F / n FORWARD Ultimate Load AFT = F X AFT / n AFT = 1.5 F / n AFT Ultimate Load RIGHT = F Y RIGHT / n RIGHT = 1.86 F / n RIGHT Ultimate Load LEFT = F Y LEFT / n LEFT = 1.86 F / n LEFT Ultimate Load UP = F Z / n UP = 5.44 F / n UP A. LOADING GENERALITIES Getting to Grips with Aircraft Weight and Balance 237 L O A D I N G O P E R A T I O N S e) Summary This whole method can be summarized in the following table: Angle Force Breakdown Tie down Point Pos. Restraint α (°) β (°) FWD + AFT - LH + RH - UP + AFT 30 150 75% F 43% F 50% F Left UP 60 90 50% F 86% F TD LA 75% F 93% F 136% F FORWARD 30 30 75% F 43% F 50% F Left UP 60 90 50% F 86% F TD LF 75% F 93% F 136% F AFT 30 210 75% F 43% F 50% F Right UP 60 90 50% F 86% F TD RA 75% F 93% F 136% F FORWARD 30 330 75% F 43% F 50% F Right UP 60 90 50% F 86% F TD RF 75% F 93% F 136% F Total Maximum Load Allowed 150% F 150% F 186% F 186% F 544% F Load Factor n FWD n AFT n LEFT n RIGHT n UP Ultimate Load 150% F / n FWD 150% F / n AFT 186% F / n LEFT 186% F / n RIGHT 544% F / n UP ULTIMATE LOAD Minimum of the Ultimate loads This method can be applied for as many as needed tie down points, adding each time a strap in the direction which limiting the ULTIMATE LOAD. Then tables like the following one can be issued and published in the loading manuals of operators. Load to be restrained Number of single stud fittings Number of straps hooked on 2 single stud fittings kg FWD AFT UP less than 800 4 1 1 2 801 to 1420 6 2 1 3 1421 to 1600 6 2 2 3 1601 to 2400 8 3 2 4 2401 to 3200 10 4 3 5 3201 to 4010 12 5 4 6 > 4010 14 6 5 7 A. LOADING GENERALITIES 238 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S Note : the recommended 30°between the rope or the strap with the main direction of restraint enables a high restrained force in the needed direction, indeed by increasing this angle, one decreases the weight that can be restrained by the item. Nevertheless some operators might choose even when applying the recommended 30°to perform the computation with an angle of 45°in order to take into account a margin in case one of the ropes in not correctly tied down. Angle Force Breakdown Tie down Point Pos. Restraint α (°) β (°) FWD + AFT - LH + RH - UP + AFT 45 145 50% F 50% F 70% F Left UP 45 90 70% F 70% F TD LA 50% F 120% F 140% F FORWARD 45 45 50% F 50% F 70% F Left UP 45 90 70% F 70% F TD LF 50% F 120% F 140% F AFT 45 225 50% F 50% F 70% F Right UP 60 90 70% F 70% F TD RA 50% F 120% F 140% F FORWARD 45 315 50% F 50% F 70% F Right UP 45 90 70% F 70% F TD RF 50% F 120% F 140% F Total Maximum Load Allowed 100% F 100% F 240% F 240% F 560% F Load Factor n FWD n AFT n LEFT n RIGHT n UP Ultimate Load 100% F / n FWD 100% F / n AFT 240% F / n LEFT 240% F / n RIGHT 560% F / n UP ULTIMATE LOAD Minimum of the Ultimate loads B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 239 L O A D I N G O P E R A T I O N S SPECIAL LOADING INTRODUCTION B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 241 L O A D I N G O P E R A T I O N S B. SPECIAL LOADING 1. LIVE ANIMALS AND PERISHABLE GOODS 1.1. Generalities 1.1.1. Main difficulties in animals and perishable goods transportation Live animals and perishable goods are particularly restricting shipments to transport. Several factors must be considered when livestock and perishable goods are transported: − Each animal specie or perishable good must be transported under specific condition of temperature, but they can be grouped into three main categories: ) Frozen goods: transported between –30°C and -12°C ) Other perishable goods: transported between -2°C and 20°C ) Live animals: transported between 0°C and 32°C − Condensation can deteriorate the quality of certain perishable goods, and may cause death of live animals. Moreover, too much condensation may cause false smoke warnings. Condensation can be caused by a moist external ambient air, a descent from high altitude into comparatively warmer air, or by moisture produced by live animals and perishable cargo. − The presence of a high rate of carbon dioxide endangers the health of live animals and reduces the quality of fruits and vegetables. Not only live animals, fruits, vegetables, but also sublimation of dry ice (used as a cooling medium for perishable goods) are the main causes for presence of CO 2 . − Ethylene is a gas given off by horticultural products (fruits, vegetables and flowers) and the ground equipment used to load and unload the cargo compartments. With some products, the ripening process is accelerated by the presence of ethylene. Therefore, in addition to the temperature, several other factors must be considered: on the one hand, animals and perishable goods need a relatively fresh air, but on the other hand they give off substances which can be harmful. B. SPECIAL LOADING 242 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 1.1.2. Recommendations To transport perishable goods and live animals in good conditions, different rules should be applied: ⇒ A ventilated cargo compartment is recommended. It allows a removal of moist air, CO 2 , and ethylene. Moreover, ventilation limits the accumulation of dust, which may avoid false smoke warnings. ⇒ In addition to the ventilation system, a heating system ensures suitable conditions for their transport. Indeed, external temperatures can be very high or very low depending on the phase of the transport considered, whereas the temperature in the compartment must remain stable. AIRBUS Industrie provides a range of optional ventilation and heating systems for installation in the FWD and AFT compartments of all the aircraft. Ventilation and heating are provided as basic in the bulk compartments of all the aircraft except the A320 family where it is optional. ⇒ Containers must be cleaned thoroughly before and, above all, after the flight. It is recommended to clean the compartments that have transported animals more frequently than given in the Aircraft Maintenance Manual. There are several reasons for this: cleaning compartments avoids the accumulation of dust, hair and feathers in the air extraction system ducts and on the lens of smoke detectors, and it limits corrosion of the aircraft due to animals excreta, sea water, fish slime or blood. ⇒ When transporting live animals and perishable goods, the basic rule is “Last in – First out”. For the cargo to arrive in the best condition, it must be loaded as near as possible to the aircraft departure time and collected as soon as possible at the destination airport. ⇒ The most direct route, or at least the most favorable route, should be used to transport live animals and perishable goods. 1.1.3. Responsibilities Transportation of live animals and/or perishable goods is under the sole responsibility of the operator who has to ensure a suitable environment for the load transported. When any live animal is on board, the form “Special Load - Notification to Captain” gives indications to the pilot about the required action on hold heating and ventilation controls (Refer to the “Operational Loading Documents” part of this manual). B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 243 L O A D I N G O P E R A T I O N S 1.2. Live animals transportation 1.2.1. Reference documents a) SAE AIR 1600 A common reference document for live animals transportation is the norm called SAE AIR 1600 edited by the Society of Automotive Engineers (USA). The purpose of this AIR (Aeronautical Information Report) is to provide information on the environmental conditions, such as temperature, humidity, carbon dioxide, noise, lighting…, that are required for the transportation of various live animals in the cargo compartments of civil commercial aircraft. It provides Air Conditioning engineers guidelines for the design of cargo air conditioning systems. b) IATA Live Animals Regulations Another reference book for the transport of live animals is the “IATA Live Animals Regulations” (LAR). This document states general rules for transportation by air of live animals. It specifies the type of container to be used and the handling procedures to be followed for individual animal species. Special attention is given to animal comfort, safety of handling staff and prevention of damage caused to aircraft. 1.2.2. Environmental limitations Animals give off heat, moisture, carbon dioxide and other gases. Combination of high temperature and high moisture is not recommended because it reduces the animals’ ability to withstand the stress. Moreover, too much carbon dioxide is dangerous to the animals’ health. Therefore, limit rates have been imposed to the airlines when live animals are transported: − Relative humidity < 80% − Concentration of carbon dioxide < 3% (this limit is going to decrease over the next years) That’s why ventilation is therefore recommended when transporting live animals. 1.2.3. Unventilated cargo compartments Most of the countries have accepted the IATA Live Animals Regulations (LAR) as the directive for animal transportation by air. Within the EU, live animals transportation is also regulated by the Council of Europe document “European Convention for the Protection of Animals during International Transport (ETS65)”. It applies to all airlines of all nationalities, operating into, out of, and transiting through any EU member State. ETS65 covers the transport of live animals in general, Article 29 is special provisions for transport by air. Paragraph 1 of Article 29 states “no animal shall be transported in conditions where air quality, temperature and pressure cannot be maintained in an appropriate range during the entire journey”. It does not specifically ban the transport of live animals in unventilated compartments, but without ventilation supply to the cargo compartment, temperature could not always be maintained in the appropriate range. B. SPECIAL LOADING 244 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 1.2.4. Specific containers Live animals must be transported in suitable clean containers. In the IATA LAR, everything can be found about container’s specificity for each animal specie. Some rules are common to all of them. Containers must be: − Strong enough to be stacked − Escape-proof for the handling staff to be in safety − Leak-proof (the use of an absorbent material is recommended, but not straw because of its combustibility) − Tied down during the flight − Not closed containers, except for tropical fish On the four sides of the container, the labels “Live Animals” and “This Way Up” must be placed. 1.2.5. Loading rules General rules must be respected: ⇒ They must be loaded close to the cargo door ⇒ They must be protected against low temperatures: − Not directly loaded on the floor of the aircraft − Not directly loaded in front of or below the air inlets ⇒ A special care must be taken concerning the neighbourhood of the animal: − Enemy animals such as cats and dogs not in sight of one another − Males and females not close to each other − Sensitive animals not close to foodstuffs − Sensitive animals not close to human remains − Sick animals and “laboratory animals” separated from healthy animals ⇒ Animals must not be in close proximity of dangerous goods such as dry ice, cryogenic liquids, radioactive materials, and poisonous and infectious substances. Note: A table presenting loading incompatibilities of live animals with other cargo loads is proposed in the “Loading Operations” part of this manual. B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 245 L O A D I N G O P E R A T I O N S 1.2.6. Live Stock Transportation Manual (LTM) Airbus has developed a simplified calculation method allowing the calculation of heat load and moisture rate in a cargo hold, while carrying live animals. This method is based on a series of graphs and a Basic Data Form published in the Airbus Live Stock Transportation Manual (LTM). This manual enables to determine whether the planned load can be carried safely under given climatic and flight conditions. The method proposed permits to calculate: • for a ventilated compartment: The Total Animal Heat Load and the Total moisture rate at the departure airport, destination airport and during the flight. Depending on the cargo option (heating or not), the method enables to evaluate if the temperature and humidity rate can be maintained in an appropriate range during the entire journey. • for an unventilated compartment: The Compartment temperature (without heat Load) at the departure airport, destination airport and during the flight, as well as the Maximum confinement time. The confinement time is the time spent in a compartment without ventilation (from door closing to door opening). The maximum confinement time is the maximum time to reach the maximum volumetric concentration of carbon dioxide (CO 2 ). It is dependent on the free air volume in the cargo compartment and the animal CO 2 production. B. SPECIAL LOADING 246 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 1.3. Perishable goods 1.3.1. IATA Perishable Cargo Handling Manual The reference guide for packaging and handling of perishable goods by air is the IATA Perishable Cargo Handling Manual. This manual is published as an industry service under the authority of the IATA Cargo Service Conference. 1.3.2. Definition Perishable cargo can be defined as “goods that will deteriorate over a given period of time, or if exposed to adverse temperatures, humidity or other environmental conditions”. As an example, this concerns different types of products such as meat, hatching eggs, flowers, fresh fruits and vegetables, sea food, vaccines and medical supply, living human organs and blood. 1.3.3. Dehydration Loss of water is a major cause of deterioration of fruits and vegetables. Since dehydration is caused by both high temperatures and low humidity, it is necessary to store fruits and vegetables under climatic conditions which are as close as possible to the ideal temperature and relative humidity. The temperature should be maintained constant during the journey, and the relative humidity required is often very high (up to 90%). 1.3.4. Package Some perishable goods, like meat and sea food, require the use of watertight refrigerated and temperature controlled containers, and must be treated as WET cargo (1) . Indeed, the temperature must remain between the following limits during the whole flight: - fresh meat or fresh fish: between 0ºC and 5ºC - frozen meat or frozen fish: below – 12ºC (1) Note: WET cargo concerns shipments containing liquids, or which by their nature may produce liquids (except dangerous goods). As an example: liquids in watertight containers, wet materials not packed in watertight containers (eg fish packed in wet ice), live animals… • Refrigerating material: Dry ice: the most effective refrigerant but classified as a “dangerous good” because it produces CO 2, which can be dangerous for live animals and can damage some perishable goods. It is used as a cooling medium and must be used for frozen goods. Gel ice: chemically based compound available in 2 forms (powder in plastic envelopes or sheets in plastic sachets). It must be frozen before use and has a gel-like consistency. Wet ice: ice made of frozen water. B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 247 L O A D I N G O P E R A T I O N S Tº dry ice < Tº gel ice < Tº wet ice The use of gel ice is recommended for several reasons: contrary to dry ice, it is harmless to food products and more durable. There is no risk of leakage and gel ice can be re-used over and over again: therefore, it is an economically attractive way to keep perishable goods cool. The labels “Perishable” and “This Way Up” must figure on the 4 sides of the package. 1.3.5. Loading rules Before loading perishable goods, it is necessary to know the incompatibilities between different product types. Note: A table presenting loading incompatibilities of perishable goods with other cargo loads is proposed in the “Loading Operations” part of this manual. • Some are incompatible because of a difference in temperature and/or humidity, others because of vapours or odours released. • Goods for human consumption must not be in close proximity of non-cremated human remains or live animals. • There must also be a separation with radioactive materials, dry ice and cryogenic liquids. Several other rules must be respected for the loading of perishable goods to avoid crushing: − Not in direct contact with the compartment floor or wall − A maximum stacking height − Not heavy package on top of fragile goods (fruits and vegetables, eggs, etc.) − Interlocking layers are recommended when a lot of ventilation is not needed. Other rules are specific to each species of perishable goods. They can be found in the IATA Perishable Cargo Handling Manual. B. SPECIAL LOADING 248 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S • Summary: Transportation of animals and perishable goods requires specific conditions that can vary depending on the product transported. Ventilation is necessary to transport live animals, and is recommended to transport perishable goods; heating is recommended for both of them. Airbus aircraft can be equipped with these two systems, either as optional or as basic. But even with ventilation and/or heating systems, a special care must be taken about incompatibilities between animals and/or perishable products. B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 249 L O A D I N G O P E R A T I O N S 2. DANGEROUS GOODS 2.1. Responsibility Transportation of dangerous goods is under the sole responsibility of the operator (the shipper). 2.2. References Two references shall be used for transportation of dangerous goods: − the ICAO Technical Instructions For the Safe Transport of Dangerous Goods by Air, adopted by the Members of the International Civil Aviation Organization (ICAO) − The IATA Dangerous Goods Regulations published annually by IATA. They contain all the requirements of the ICAO Technical Instructions, but IATA has included additional requirements that are more restrictive. The IATA Dangerous Goods Regulations are more applicable for practical reference by the industry, but as indicated in the preface of the IATA Dangerous Goods Regulations, “Annex 18 to the Chicago convention and the associated Technical Instructions for the Safe Transport of Dangerous Goods by Air are recognized as the sole authentic legal source material in the air transport of dangerous goods”. In addition to these two reference manuals, national regulations from e.g. FAA or JAA may also apply as applicable and furthermore the local authorities of the country of departure and country of arrival may have strict regulations which have to be taken into account. 2.3. Definitions Dangerous goods are “articles or substances which are capable of posing a significant risk to health, safety or property when transported by air” (per IATA Dangerous Goods Regulations). There are three types of dangerous goods: − goods too dangerous to be transported by air − goods transported with cargo aircraft only (called CAO shipments) − goods transported both with cargo and passenger aircraft To know to which category belongs a given good, refer to the Limitations section of the IATA Dangerous Goods Regulations. In this section, you will also find the list of state variations concerning dangerous goods. Some cargo may be hidden dangerous cargo: indeed, declared under a general description, some cargo can hide hazards that may not be apparent. Here are some examples of hidden dangerous goods: − Articles found in passengers’ baggage that may contain flammable gas or liquid, matches, aerosols, etc. − Frozen perishable goods or vaccines that may be packed with Dry Ice (solid carbon dioxide) − Parts of automobiles that may contain wet batteries or gasoline − etc. B. SPECIAL LOADING 250 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 2.4. Identification “An operator shall take all reasonable measures to ensure that articles and substances are classified as dangerous goods as specified in the Technical Instructions.” (JAR–OPS 1.1170). A number, in the United Nations classification system, is given to each dangerous article or substance. Each substance has its own UN number. This number is used for all ways of transport (not only air-transport) to identify the substance. The letters “UN” precede this number (when the UN number is not assigned yet, a temporary “ID” number in the 8000 series is assigned). Symbol: 2.5. Classification Moreover, dangerous goods are classified into 9 hazard classes. Each hazard class is divided into several hazards divisions and specific labels are applied to each one of these classes and/or divisions: 2.5.1. Explosives − Division 1.1 - Articles and substances having a mass explosion hazard − Division 1.2 - Articles and substances having a projection hazard but not a mass explosion hazard − Division 1.3 - Articles and substances having a fire hazard, a minor blast hazard and/or a minor projection hazard but not a mass explosion hazard − Division 1.4 - Articles and substances presenting no significant hazard − Division 1.5 - Very insensitive substances having a mass explosion hazard − Division 1.6 - Extremely insensitive articles which do not have a mass explosion hazard Applicable labels are: B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 251 L O A D I N G O P E R A T I O N S 2.5.2. Gases − Division 2.1 - Flammable gas − Division 2.2 - Non-flammable, non toxic gas − Division 2.3 - Toxic gas Applicable labels are: 2.5.3. Flammable liquids Applicable label is: 2.5.4. Flammable solids; Substances liable to spontaneous combustion; Substances which, in contact with water, emit flammable gases − Division 4.1 - Flammable solid − Division 4.2 - Substances liable to spontaneous combustion − Division 4.3 - Substances which, in contact with water, emit flammable gas Applicable labels are: B. SPECIAL LOADING 252 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 2.5.5. Oxidizing substances and Organic Peroxide − Division 5.1 - Oxidizer − Division 5.2 - Organic peroxides Applicable labels are: 2.5.6. Toxic and infectious substances − Division 6.1 - Toxic substances − Division 6.2 - Infectious substances Applicable labels are: 2.5.7. Radioactive material Applicable labels are: B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 253 L O A D I N G O P E R A T I O N S 2.5.8. Corrosives Applicable label is: 2.5.9. Miscellaneous dangerous goods Applicable label is: B. SPECIAL LOADING 254 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 2.6. Packing The order in which classes and divisions are numbered does not imply a relative degree of danger. The element that gives an indication on the degree of hazard substances present is the packing group: − Packing group I ➙ great danger − Packing group II ➙ medium danger − Packing group III ➙ minor danger Criteria for packing groups have only been developed for some classes and divisions. When a given substance presents more than one hazard, the most stringent class and packing group must be applied to this substance; the least stringent hazard is called the subsidiary hazard. A table provided in the 3 rd section of the IATA Dangerous Goods Regulations helps in determining which one of the two hazards must be regarded as the primary hazard. Example: CLASS OR DIVISION PACKING GROUP A 4.2 II B 5.1 III C 5.1 I − A + B → 4.2, II - Subsidiary risk: 5.1 − A + C → 5.1, I - Subsidiary risk: 4.2 Therefore, before packing any dangerous good, the shipper must: − Identify correctly and fully all dangerous articles and substances before transportation − Classify each item by determining its class or division and its subsidiary hazard − When it is possible, assign each item to one of the three packing groups The shipper is responsible for all aspects of the packing of dangerous goods in compliance with the IATA Dangerous Goods Regulations. In the 5 th section of the IATA Dangerous Goods Regulation, the shipper can find packing instructions that detail the type of specifications required to transport each product depending on its class. Most dangerous goods must be packed with both an inner and an outer packaging. Here are general packing requirements (for more details, refer to the 5 th section of the IATA Dangerous Goods Regulations): − Dangerous goods packaging must be of a good quality − Packaging in direct contact with dangerous goods must be resistant to any chemical action of such goods − Salvage packaging must be used for damaged, defective or leaking dangerous goods − Packaging can be reused or reconditioned under specific conditions − Several dangerous goods may be transported in the same outer packaging under specific conditions One last condition about package of dangerous goods is that it must be of such a size that there is enough space to affix all required markings and labels. B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 255 L O A D I N G O P E R A T I O N S 2.7. Marking and labeling All packages containing dangerous goods are to be marked and labeled in order to ensure immediate identification during all phases of transportation. − First of all, the packaging must bear the UN number and the shipping name of the substance it contains. − Each package is labeled thanks to the dangerous goods hazard labels we have seen above (minimum size: 100 x 100 mm). − If necessary, handling information shall be shown on the packages thanks to the following labels: This Way Up Cargo Aircraft Only B. SPECIAL LOADING 256 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 2.8. Documents The presence of special loads such as dangerous goods should be noted on the load sheet and the load message. Moreover, for each shipment containing dangerous goods, the shipper must fill in special forms: 2.8.1. Air Waybill The IATA Air Waybill Handbook gives all the instructions necessary to complete an Air Waybill. An Air Waybill is compulsory whenever dangerous goods are transported. The “Handling information” box of the Air Waybill gives information about: − the presence of dangerous goods on board − the presence or not of a “Shipper’s Declaration for Dangerous Goods” − the way the dangerous goods must be transported (Cargo Aircraft Only or Passenger aircraft) Example: Dangerous goods for which a Shipper’s Declaration is required and transported on a passenger aircraft. B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 257 L O A D I N G O P E R A T I O N S 2.8.2. Shipper’s Declaration for Dangerous Goods Thanks to the “Shipper’s Declaration for Dangerous Goods”, the shipper certifies that dangerous goods have been properly prepared for shipment. A Shipper’s Declaration for Dangerous Goods is provided on the following page. 3 9 8 4 7 6 5 2 1 Red Hatching 1 - Information about the shipper 2 - Information about the consignee 3 - Number of the Air Waybill attached 4 - Page number 5 - Enter the full names of the airports (not ICAO codes) 6 - Radioactive material must not be on the same declaration as other dangerous goods, except dry ice (used as a refrigerant for perishable goods — cf. next part). 7 - Information about dangerous goods transported 8 - Particular information about the shipment 9 - The shipper commits himself to respect regulations concerning transportation of the shipment B. SPECIAL LOADING 258 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 2.8.3. Special Load – Notification to Captain Thanks to this form, the flight crew is aware of the presence of dangerous goods on board. It is also used to indicate the presence of live animals or perishable cargo which transportation is developed below. The following form is used: SUCH AS LIVE ANIMALS OR PERISHABLE GOODS 2.9. Handling and loading Competent persons that have received an appropriate training concerning dangerous goods shall only execute handling and loading. A few rules are to be respected: − First of all, before loading, it is necessary to inspect the outer packaging of dangerous goods to determine there is no hole or leakage. Moreover, they must always be handled with care. − Handling instructions on the package must be respected (This Way Up, etc.). − Dangerous goods must never be carried on the same deck as passengers or crewmembers. − Some goods may react dangerously with others. To avoid any interaction, other loads or being loaded in different compartments shall physically separate incompatible goods from others. The table of incompatibilities is provided in the AHM 645. − When an Auxiliary Center Tank (ACT) is installed in a cargo compartment, no combustible, corrosive or explosive material shall be transported in this compartment − After unloading, the outer packaging must be inspected for evidence of damage or leakage. B. SPECIAL LOADING Getting to Grips with Aircraft Weight and Balance 259 L O A D I N G O P E R A T I O N S 2.10. Special shipments 2.10.1. RADIOACTIVE MATERIALS There are three different categories of radioactive materials depending on the Transport Index (TI) of the package. Its value is shown on the labels affixed on the package. The TI number expresses the maximum radiation dose rate at 1 meter away from the external surface of a package containing dangerous goods. − Category I - no TI − Category II – 0 < TI ≤ 1.0 − Category III – 1.1 ≤ TI ≤ 10.0 The transport index of a single package is limited to 10 and the transport index of the whole shipment is limited to 50. There is no specific restriction concerning radioactive materials from category I. Packaging containing radioactive materials of categories II and III must be separated from live animals, hatching eggs and undeveloped photographic films. Moreover, during the flight, minimum horizontal and vertical distances must separate these radioactive packages from each other and from passengers. 2.10.2. CARBON DIOXIDE, SOLID (DRY ICE) Dry ice is used as a refrigerant for perishable goods transportation. Loading regulations shall be applied such as: − When there is dry ice in a compartment, it must be ventilated before the staff enters in it. − Dry ice shall not be loaded in close proximity of live animals or hatching eggs. 2.10.3. CORROSIVES Corrosives shall not be loaded next to dangerous goods classified as explosives, flammable solids, oxidizing substances or organic peroxides. Moreover, whenever ACTs are installed in the aircraft, no corrosive materials should be transported in close proximity of them. 2.10.4. TOXIC AND INFECTIOUS SUBSTANCES Such substances shall not be loaded in the same section or ULD as live animals or foodstuffs. Even when they are loaded in different ULDs, the ULDs must be separated C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 261 L O A D I N G O P E R A T I O N S OPERATIONAL LOADING DOCUMENTS INTRODUCTION IATA AHM part 5 describes in detail all the different types of traffic documents and messages to be used for handling operations. This manual must be used as a reference to help building specific airline policies in accordance with national regulations. Our goal in this chapter is to provide the reader with a general description of the main documents used in operations for a better understanding of the load control function. These main documents are: − Loading Instruction / Report form (LIR) − Container/Pallet distribution message (CPM) − Loadsheet − Loadmessage (LDM) − Balance chart / balance table In these different documents, codes are used and it is recommended that operators comply with the proposed codification of IATA AHM 510 recalled hereafter. C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 263 L O A D I N G O P E R A T I O N S C. OPERATIONAL LOADING DOCUMENTS 1. LOAD AND VOLUME INFORMATION CODES 1.1. Load Information Codes The following codes enable to define the type and priority of deadload transported in the cargo holds. To be used on the LIR and the CPM. Code Description B Baggage C Cargo D Crew baggage E Equipment in compartment F First class baggage and/or priority handled baggage H ULD and/or its load to be transshipped to a connecting flight (destination or flight number indicated in Supplementary Information part of the CPM) M Mail N No ULD at position Q Courier baggage S Sort on arrival T Load for transfer to connecting flights U Unserviceable ULD W Cargo in security controlled ULD X Empty ULD Z Load deliberately mixed by destination when these destinations are known to be beyond a planned 1.2. ULD Load volume codes The following codes provide a transit station with information about the available volume in a cargo section or an ULD. To be used on the LIR and the CPM. Code Description 0 No volume available 1 Quarter volume available 2 Half volume available 3 Three quarters volume available C. Operational Loading Documents 264 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 1.3. Codes used for loads requiring special attention The following codes (non exhaustive list) indicate in the LIR, CPM, Loadsheet, and LDM, the content of the dead load requiring special attention. Code Description LDM format Remark AOG Spare part for Aircraft On Ground .AOG/12L ULD position 12L AVI Live Animals .AVI/4 Loaded in CPT4 BAL Ballast hold loaded .BAL/5/100 100 kg ballast in CPT5 BED Stretcher installed .BED/6/2Y 6 seats blocked by 2 pax in Y BEH Stretcher in cargo hold .BEH/33/50 Position 33, 50 kg BIG Item loaded on two or more pallets .BIG/11P12P/26 50 2650 kg loaded on 11P + 12P COM Company mail .COM/42L/216 216 kg loaded in 42L CSU Catering equipment not used for flight .CSU/22R/500 500 kg loaded in 22R DHC Crew occupying pax seats (not on duty) .DHC/0/2/5 2 seats in B class, 5 in Y class DIP Diplomatic Mail .DIP/1/2 2 bags loaded in CPT1 EAT Foodstuff for human consumption .EAT/31R Loaded in 31R EIC Miscellaneous items not included in DOW .EIC/4/50 50 kg loaded in CPT4 FIL Undeveloped Film/Unexposed film .FIL/3 CPT3 FKT Flight Kit .FKT/53/450 450 kg loaded in section 53 HEA Heavy cargo (above 150 kg per piece) .HEA/2/216 216 kg loaded in CPT2 HEG Hatching eggs .HEG/32L ULD position 32L HUM Human remains in Coffins .HUM/42P/210 210 kg loaded in 42P ICE Carbon dioxide, Dry ice .ICE/11R Loaded in 11R LHO Live Human Organs/Blood .LHO/2 Loaded in CPT2 MAG Magnetized material Not to be used Not mentioned in LDM MOS Miscellaneous Operational Staff .MOS/0/2/0 2 seats in B class NIL No item loaded OBX Obnoxious deadload .OBX/12P Loaded in 12P PAD Passenger Available for Disembarkation .PAD/0/1/5 1 seat in B class, 5 in Y class PEA Hunting trophies, skin, … .PEA/2 Loaded in CPT2 PEF Flowers .PEF/4 PEM Meat .PEM/11P Loaded in 11P PEP Fruit and vegetables .PEP/3 Loaded in CPT3 PER Perishable goods .PER/41P Loaded in 41P PES Seafood/Fish for human consumption .PES/1 Loaded in CPT1 R... Dangerous goods .RNG/31L Loaded in 31L RRY Radioactive Category II and III .RRY/41P/6PT4 Sum of Transport Indexes = 6.4 SOC Seats occupied by baggage, cargo, mail .SOC/6/12 6 seats in F/B class, 12 in Y class VAL Valuable cargo Not to be used WET Wet materials not packed in watertight .WET/41R Eg : fish packed in wet ice XPS Priority small package .XPS/41P C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 265 L O A D I N G O P E R A T I O N S 2. LOADING INSTRUCTION / REPORT (LIR) 2.1. Introduction This form is a means of communication between the Load Planner and the Loading Supervisor. On the one hand, it allows the Load Planner to give loading and off-loading instructions to the Loading Supervisor, and on the other hand, it allows the Loading Supervisor to know everything about the shipment (nature, distribution, etc…) and to report the loading distribution is effectively performed. The Loading Instruction / Report form (LIR), is prepared and filled in by the Load Planner once he knows how much load can be transported. To determine this data, the load planner needs information from : − Passenger booking : to calculate the forecasted passenger weight and associated − Baggage weight (number of containers required in case of CLS) − Dispatch : to know what is the available payload according to the fuel required for the flight − Incoming LDM/CPM : to know the cargo distribution and if there is transit cargo/mail in case of multi-sector flights − Cargo department : to know if cargo is available for the flight − Aircraft type : weight limitations, CG limitations, cargo options (ventilation, heating) Once the load is known, the Load planner determines its distribution into the cargo holds, taking into account several constraints such as Zero Fuel CG position, weight limitations, loading/off- loading rules, incompatibilities, specific loading constraints (dangerous goods, live animals, perishable goods…). C. Operational Loading Documents 266 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 2.2. Manual LIR The layout of the LIR may vary with aircraft type or with airline, but for all of them, the following information is required, as stated in IATA AHM 515. A - Heading: Station, Flight number, Aircraft registration, Destination(s), Local date, name of the Load Planner who prepared it. B - Compartment number and Weight limitations: clearly indicates the weight limitations for each cargo hold. C - Arrival (for multi-sector flights only): gives details about the incoming loads for intermediate stops. Cargo that must be off-loaded at the transit station may be encircled, but the loading agent knows what he must off-load, since the destination of each load is clearly indicated on the form. Information contained in this section is copied from the incoming CPM for aircraft equipped with ULDs, and from the incoming LDM for others. D - Loading Instructions: Gives indications on where the load must be stowed, and of any change in the transit load position in case of multi-sector flights. In this case, the destination must be clearly indicated by the 3-letter IATA airport codes. E - Loading reports: completed by the Loading Supervisor, it is used to confirm that the aircraft has been loaded in accordance with the given instructions. Information shown in this section reflects the exact state of the shipment loaded in the aircraft before departure. Any deviations from the original Loading Instructions must be noted or transmitted before the flight departure to the loadsheet agent. F - Special instructions: gives any information that might be considered as important or useful by the Load Planner, such as dangerous goods, live animals, lashing of heavy items, relocation of some cargo to balance the aircraft, airway bill of dangerous goods… G - Signatures: Two names and two signatures are required: The Load planner who prepared the Loading Instructions The Loading Supervisor, who performed the Loading, to confirm that the aircraft is loaded in accordance with the instructions or to advise of any deviations. The Load Planner has to fill in the header part, the arrival part from the incoming LDM/CPM (in case of multi-sector flights) as well as the Loading Instructions part. To give its loading instructions, the load planner must use, for each hold section, the following items: − the destination of the shipment (3-letter IATA code) − the ULD type and ID code (for ULDs aircraft) − the content of the section (Baggage, cargo, mail…) through a one letter code (as per AHM 510) − the estimated weight of the load − the nature of the shipment in case of special loading (as per AHM 510) − the available volume in the section (as per AHM 510) C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 267 L O A D I N G O P E R A T I O N S C. Operational Loading Documents 268 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S Example : 41P JFK/PAG 1234AI/ C/2480/AVI.PER Hold section Destination Pallet ID Content Weight Special load 41P JFK PAG 1234AI C (Cargo) 2480 kg AVI.PER (Live Animals + Perishable goods) 12L JFK/F2 Hold section Destination Pallet ID Volume 12L JFK F (First class/priority baggage) 2 (Half volume available C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 269 L O A D I N G O P E R A T I O N S 2.3. EDP LIR Nowadays, integrated load control systems enable to prepare loading instructions and to visualize simultaneously the effect of the load on the center of gravity of the aircraft. To avoid reporting the load distribution on a manual LIR, a computerized “Loading Instruction / Report” form can be directly printed. According to AHM 514, it is recommended to issue a Loading Instruction/report form for each departing flight. These reports must be signed by the persons responsible for loading and/or off- loading. Note that due to limited space, only the occupied ULD positions or hold sections may be shown. In case of loads requiring special attention, AHM 514 recommends a “Summary of special loads” to be issued. • Example of an EDP LIR: A CPT 1MAX 13380 : 12PPAG 2503AI : ONLOAD:JFK C / 1850 : SPECS:SEE SUMMARY : REPORT:1850 Cpt capacity : 13380 kg Hold section : 12P Pallet ID : PAG 2503AI Origin : CDG Destination : JFK Content : Cargo (1850 kg) Special load : RFL (See summary : one piece, Airway Bill 034 99222) Report : 1850 kg (Actual weight reported by the loading supervisor) B CPT 2MAX 10206 : 21PPAG 5421AI : TRANSIT:JFK C / 3225 : SPECS:SEE SUMMARY : REPORT:3225 Cpt capacity : 10206 kg Hold section : 21P Pallet ID : PAG 5421AI Origin : (Transit in CDG) Destination : JFK Content : Cargo (3225 kg) Special load : RRY (See summary : one piece, Transport Index 2, Airway Bill 055 235324) Report : 3225 kg (Actual weight reported by the loading supervisor) C. Operational Loading Documents 270 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S • EDP LIR example LOADING INSTRUCTION/REPORT PREPARED BY Jones EDNO ALL WEIGHTS IN KILOS 01 FROM / TO FLIGHT A/C REG VERSION GATE TARMAC DATE TIME CDG JFK AI0533 OOTPA C18/Y264 B40 H10 30DEC00 1405 PLANNED JOINING LOAD JFK F 0 C 16 Y204 C 10785 M 0 B 4300 JOINING SPECS : SEE SUMMARY TRANSIT SPECS: SEE SUMMARY LOADING INSTRUCTIONS ************************************************************************************************************************************** CPT 1 MAX 13380 : : 12P PAG2503AI : : ONLOAD: JFK C / 1850 : : SPECS: SEE SUMMARY : : REPORT: 1850 : …………………………………………………………………………………………………………..……….: : 13P PAG3251AI : : ONLOAD: JFK C / 1980 :……………...……. REPORT: 1980 CPT 1 TOTAL : 3 830 ************************************************************************************************************************************** CPT 2 MAX 10206 : : 21P PAG5421AI : : TRANSIT: JFK C / 3225 : : SPECS: SEE SUMMARY : : REPORT: 3225 : …………………………………………………………………………………………………………..……….: : 22P PAG4521AI : : TRANSIT JFK C / 3730 :………..………….. REPORT: 3730 CPT 2 TOTAL : 6 955 ************************************************************************************************************************************** CPT 4 MAX 10206 : : 41L AKE1245AI : 41R AKE4567AI : : ONLOAD: JFK B / 810 : ONLOAD: JFK B / 810 : : REPORT: 800 : REPORT: 800 : …………………………………………………………………………………………………………..……….: : 42L AKE4561AI : 42R AKE8424AI : : ONLOAD: JFK B / 810 : ONLOAD: JFK B / 810 : : REPORT: 750 : REPORT: 750 : …………………………………………………………………………………………………………..……….: : 43L AKE5624AI : 43R AKE4093AI : : ONLOAD: JFK B / 810 : ONLOAD: JFK F / 480 :………...…………. : REPORT: 800 : REPORT: 400 CPT 2 TOTAL : 4300 ************************************************************************************************************************************** : SI THIS AIRCRAFT HAS BEEN LOADED IN ACCORDANCE WITH THESE INSTRUCTIONS AND THE DEVIATIONS SHOWN ON THIS REPORT. THE CONTAINERS / PALLETS AND BULKLOAD HAVE BEEN SECURED IN ACCORDANCE WITH COMPANY INSTRUCTIONS. SIGNATURE JONES Italic characters represent the loading supervisor inputs A B C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 271 L O A D I N G O P E R A T I O N S • “Summary of special loads” - Example FROM / TO FLIGHT A/C REG VERSION GATE TARMAC DATE TIME CDG JFK AI0533 OOTPA C18/Y264 B40 H10 30DEC00 1405 LOCN JOIN/ TRAN DEST CAT IMP PCS WEIGHT TI AWB ************************************************************************************************************** 12P JOIN JFK C RFL 1 034 99222 ………………………………………………………………………………………………………………... 21P TRAN JFK C RRY 1 Opt 2 055 234324 ************************************************************************************************************** SI ….. 3. CONTAINER/PALLET DISTRIBUTION MESSAGE (CPM) The Container/Pallet distribution message only concerns aircraft equipped with Unit Load Devices (ULDs). This message shall provide the type and the distribution of the ULDs, their destination (for multi-sector flights), as well as their weight and content. It is not requested to send a loadmessage on a single leg flight or on the last leg of a multi-sector flight. Nevertheless, most of the carriers systematically send CPMs as it enables the destination station to prepare the adequate equipment and manpower for handling containers and pallets. A need exists for an automatic readable format for the CPM. Indeed, this can allow both automatic transmission and reading of any CPM, as well as automatic distribution of ULDs by EDP systems. IATA AHM 587 gives information about the standard format of the Container/Pallet distribution message. The codes used for the CPM come from IATA AHM 510. All the ULD positions, including those not occupied by an ULD, must be shown on the message. The message is composed of four parts: 1- Teletype addresses and communication reference 2- Standard message identifier and flight record 3- Distribution and load information 4- Supplementary information C. Operational Loading Documents 272 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S CPM example QU JFKKLAI JFKKKAI CDGKKAI # ## # .CDGKLAI AI/301505 CPM & && & AI533/30.OOTPA.C18/Y264 -11L/X-11R/X -12P/JFK/1850/C.RRY/1PT5 -13P/JFK/1980/C.FIL -21P/JFK/3225/C.PER -22P/JFK/3730/C -31P/N -32P/N -41L/JFK/800/B0-41R/JFK/800/B0 -42L/JFK/750/B1-42R/JFK/750/H/TB1 $ $$ $ -43L/JFK/800/B1-43R/JFK/400/F3 % %% % SI -42R/UA256/PIT/TB QU JFKKLAI JFKKKAI CDGKKAI Priority (urgent) Address 1 Address 2 Address 3 .CDGKLAI AI/301505 Originator Facilit y / D at e / Time # ## # AI / 30 / 15h05 CPM (Message identifier) AI533/30 .OOTPA .C18/Y264 & && & Flight number/date Aircraft registration Aircraft configurati on -11L/X-11R/X Empty ULD in position 11L – Empty ULD in position 11R -12P/JFK/1850/C.RRY/1PT5 ULD position 12P, destination JFK, weighing 1850 kg, cargo load containing radioactive materials whose sum of Transport Indexes is equal to 1.5 -31P/N Position 31P empty (No ULD) -42L/JFK/750/B1 ULD position 42L, destination JFK, weighing 750 kg, containing baggage, ¼ volume available -42R/JFK/750/H/TB1 $ $$ $ ULD position 42R, destination JFK, weighing 750 kg, containing a load to be transferred to a connecting flight (destination or flight number indicated in SI), transfer baggage, ¼ volume available SI (Supplementary Information) –42R/UA256/PIT/TB % %% % ULD position 42R, connecting flight UA256 to PIT, baggage to be transferred onto this flight C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 273 L O A D I N G O P E R A T I O N S 4. LOADSHEET 4.1. Introduction The loadsheet is a document prepared and signed by the loadsheet agent at the departure airport. This form gives information about the weight of the aircraft as well as the distribution of the load in the different cargo holds. In case of multi-sector flights, the weight that must be unloaded at the different stations is indicated. The loadsheet allows to check, before each departure, that the weight of the shipment is consistent with the structural limitations of the aircraft. The loadsheet must reflect the actual state of the aircraft before takeoff. It is often necessary to adjust it after completion to take into account “Last Minutes Changes” (LMC). The loadsheet must be issued in not more than four-fold, distributed as follows: − one copy for the aircraft − one copy for the departure station file − one or two copies for the carrier, if required Airlines often use their own loadsheet format. Nevertheless, IATA AHM 516 gives recommendations about the kind of information that must appear on a loadsheet, which can be manual or computerized (EDP loadsheet). C. Operational Loading Documents 274 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 4.2. Manual loadsheet • Manual Loadsheet example A 1 2 3 4 5 6 9 8 10 7 B 1 2 3 C 1 2 3 4 5 6 D 1 2 3 4 5 6 9 8 7 10 E 1 2 3 4 5 F 1 2 3 4 5 6 G 1 2 3 4 5 6 7 C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 275 L O A D I N G O P E R A T I O N S A : Addresses and heading 1 - Priority code (QU = urgent, QD = Standard) 2 - Teletype address for loadmessage as required (XXXYYZZ) . XXX : destination airport (3 letters IATA code) . YY : destination department. As an example: . eg KL (K= Operations department, L = Load control department) . eg KK (K = Operations department, K = Station manager) . ZZ: code of the company (airline code or XH for external handling companies) 3 - Teletype address of originator (XXXYYZZ) 4 - Recharge facility/Date/Time : eg AF/251005 . Recharge facility : AF . Date : 25 . Time : 10h05 AM 5 - Operators initial 6 - Standard message indicator (LDM for loadmessage) 7 - Flight number/identifier : eg SN551/25 . Flight number : SN551 . Identifier : 25 (date as an example) 8 - Aircraft registration 9 - Version code of the aircraft used : eg C42Y218 . C42 : 42 business seats . Y218 : 218 economic seats 10 - Number of cockpit crew / cabin crew : eg 2/9 or 2/2/7 . 2/9 : 2 cockpit crew + 9 cabin crew . 2/2/7 : 2 cockpit crew + 2 cabin crew male + 7 cabin crew female B : Operating weight calculation 1 - Dry Operating Weight = Basic weight + Crew + Pantry 2 - Takeoff fuel from fuelling order 3 - Operating weight = Dry operating weight + Takeoff fuel C : Allowed traffic load calculation 1 - MZFW = Certified Maximum Zero Fuel Weight 2 - MTOW = Certified Maximum TakeOff Weight 3 - MLW = Certified Maximum Landing Weight 4 - Trip fuel from dispatch 5 - Allowed weight for takeoff = Lowest of (MZFW+Takeoff Fuel), MTOW, (MLW+Trip Fuel) 6 - Allowed traffic load = Allowed weight for takeoff (C5) - Operating weight (B3) C. Operational Loading Documents 276 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S D : Load information per destination and totals This section provides information about the number of passengers as well as on the deadload (weight and distribution) for each destination of the flight. 1 - Destination airports (several in case of multi-sector flights) 2 - Number of passengers in transit and continuing to the next destination airport (Males, Adults/Females, Children, Infants, Total cabin baggage weight (1) ) 3 - Number of passengers joining at this airport (Males, Adults/Females, Children, Infants, Cabin baggage (1) ) 4 - Total weight of deadload (Tr: deadload in transit, B: joining baggage, C: joining cargo, M: joining mail) 5 - Weight distribution per cargo hold and per type (Tr, B, C, M) 6 - Total number of seats occupied by outgoing passengers per class, including PADs (Passengers Available for Disembarkation: no firm booking, low priority) 7 - Total number of seats occupied by outgoing PADs per class 8 - Additional remark as per IATA AHM 510 recommendations (HEA, AVI, RRY, RFL, HUM…) 9 - Number of outgoing passengers and outgoing deadload per destination 10 - Total number of outgoing passengers and outgoing deadload (1) When not included in passenger weight E : Actual gross weight calculation 1 - Total Traffic Load = Total outgoing deadload (D10) + Total cabin baggage weight (1) (D10) + Total outgoing passenger number (D10) x passenger weight (2) 2 - ZFW = Total traffic Load (E1) + Dry operating weight (B1) 3 - TOW = ZFW (E2) + Takeoff fuel (B2) 4 - LW = TOW (E3) - Trip fuel (C4) 5 - Underload before LMC (3) = Allowed traffic load (C6) – Total traffic load (E1) (1) Irrelevant when cabin baggage weight is included in the passenger weight (2) Passenger weight with or without baggage weight (company policy) (3) The underload before LMC represents the extra weight that can be added at the last minute, while structural limitations are still respected. C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 277 L O A D I N G O P E R A T I O N S F : Last minutes changes (LMC) As the loadsheet must reflect the actual loaded state of the aircraft before departure, it is often necessary to adjust it after completion. This is the aim of Last Minute Changes (LMC). Generally, only changes in the weight or distribution of the traffic load (passengers, baggage, cargo and mail) should be mentioned in the LMC box. Nevertheless, any deviation of the DOW conditions could be added as well. 1 - Dest : Destination of LMC 2 - Specification : Kind of LMC (number of passengers, weight of deadload) 3 - Cpt: Cabin section or cargo compartment in which the LMC is added 4 - +/-: Indication of on or off-load 5 - Weight : Weight increment or decrement for the specific LMC 6 - LMC Total +/- : Sum of all LMC weights (on or off-load) The total weight increase due to LMC (F6) must not exceed the underload before LMC (E5). No subsequent corrections are to be made to the previously calculated ZFW (E2), TOW (E3) and LW (E4), provided the weight increment remains below a pre-determined tolerance. This tolerance should be established per aircraft type (company policy). When the tolerance is exceeded, a new loadsheet must be issued. G : Supplementary information and notes 1 - SI: supplementary information transmitted with LDM (free format) 2 - Notes: Information not transmitted with LDM 3 - Balance condition: balance conditions according to carriers requirement (MACZFW, MACTOW,…) as per AHM 050. 4 - Seating conditions: according to carrier requirement 5 - Total passengers: Total number of passengers on board (including LMC) 6 - Prepared by: Loadsheet agent’s signature 7 - Approved by: Captain’s signature C. Operational Loading Documents 278 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 4.3. EDP Loadsheet With computerized Load control systems, cargo, mail and passenger boarding information are interconnected. EDP loadsheets can be issued very quickly at the last minute, generally besides the aircraft. That’s why it is advisable to adjust passenger and load figures before the final version is printed or sent to the aircraft. This enables to avoid Last Minute Changes on the loadsheet. According to IATA AHM 517, an EDP loadsheet must look like the following example: • EDP loadsheet example LOADSHEET CHECKED APPROVED EDNO ALL WEIGHTS IN KILOS 02 FROM/TO FLIGHT A/C REG VERSION CREW DATE TIME CDG JFK AI0533 OOTPA C18Y264 2/9 30DEC00 1405 WEIGHT DISTRIBUTION LOAD IN COMPARTMENTS 10785 1/3830 2/6955 4/4300 PASSENGER/CABIN BAG 16905 190/ 27/ 3 TTL 220 CAB PAX CY 16/204 SOC BLKD ************************************************************************************************************** TOTAL TRAFFIC LOAD 27690 DRY OPERATING WEIGHT 123250 ZERO FUEL WEIGHT 150940 MAX 168000 TAKE OFF FUEL 65500 TAKE OFF WEIGHT ACTUAL 216440 MAX 230000 TRIP FUEL 58600 LANDING WEIGHT ACTUAL 157840 MAX 180000 BALANCE AND SEATING CONDITIONS LAST MINUTE CHANGES DEST SPEC CL/CPT WEIGHT .. UNDERLOAD BEFORE LMC 13560 LMC TOTAL ************************************************************************************************************** CAPTAIN INFORMATION/NOTES ….. LOAD MESSAGE BEFORE LMC ….. END LOADSHEET EDNO 02 AI0533 30DEC00 140535 Deadload information Cargo 1 : 3830 kg Cargo 2 : 6955 kg Cargo 4 : 4300 kg Total : 10785 kg Passenger information Adult : 190 / Children : 27 / Infant : 3 Business class (C) : 16 pax Economic class (Y) : 204 pax Total number : 220 pax Total weight : 16905 kg A B BALANCE AND SEATING CONDITIONS According to carrier requirement (Refer to “Balance calculation methods”) C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 279 L O A D I N G O P E R A T I O N S 4.4. ACARS loadsheet The ACARS loadsheet format is designed to provide only essential data. According to IATA AHM 518, the loadsheet must be headed “Prelim” or “Final” to prevent from any confusion. When the ACARS loadsheet is generated by an EDP system, this system must ensure that only one final loadsheet will be transmitted. The transmission by the loadsheet agent must be done at a time that ensures that no further adjustments will be necessary. It is recommended to get the acknowledgement from the cockpit crew. After transmission of the final loadsheet, any correction should be done verbally. A copy of the final loadsheet must be printed on ground, signed by the loadsheet agent and stored in the flight’s file. • ACARS loadsheet example LOADSHEET FINAL 1505 AI05333/30 30DEC00 CDG JFK OOTPA 2/9 ZFW 150940 MAX 168000 TOF 65500 TOW 216440 MAX 230000 TIF 58600 LAW 157840 MAX 180000 UNDLD 13560 PAX /0/16/204 TTL220 SI .. ENDAI0533 ACARS loadsheet status : Final Sent at : 15h05 Flight Number/Day : AI0533/30 Date : 30 DEC 2000 Departure : CDG Arrival : JFK A/C Registration : OOTPA Crew : 2 cockpit / 9 cabin Zero Fuel Weight : 150940 kg Max Zero Fuel Weight : 168000 kg Take Off Fuel : 65500 kg Take Off Weight : 216440 kg Max Take Off Weight : 230000 kg Trip Fuel : 58600 kg Landing weight : 157840 kg Max Landing Weight : 180000 kg Underload : 13560 kg Passengers per class : 16 B / 204 Y Total number of pax : 220 SI : Supplementary Information BALANCE AND SEATING CONDITIONS According to carrier requirement (Refer to “Balance calculation methods”) C. Operational Loading Documents 280 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 5. BALANCE CALCULATION METHODS 5.1. Introduction It is necessary to determine, before takeoff, the center of gravity position of the aircraft. The main reason is the flight safety. Indeed, it is necessary to ensure that the aircraft CG will remain within pre-determined limits during the whole flight. Another reason is an operational reason: the crew must be able to correctly trim the aircraft for takeoff by selecting the appropriate THS (Trimmable Horizontal Stabilizer) angle, directly deduced from the center of gravity position of the aircraft. An aircraft is a combination of several items that have a particular weight and a particular location. Different methods are available to determine the influence of each item on the aircraft balance: 1 Manual method : Balance chart / Balance table 2 EDP method 5.2. Manual balance calculation method 5.2.1. Balance chart C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 281 L O A D I N G O P E R A T I O N S • Balance chart example A J B H I C D F E K G C. Operational Loading Documents 282 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S • Fuel index table example F IATA AHM 519 gives information about the kind of information that must appear on a balance chart: A – The type of aircraft and version B – A drawing of the aircraft layout showing : . The passenger cabin section . The position and numbering of holds and compartments C – Index units as the first scale D – For each compartment or cabin section : . Vertical or sloping lines corresponding to index variations . Arrows indicating direction and value of each pitch E – A balance diagram with shaded areas outside the forward and aft balance limits F – The influence of fuel on weight and balance. It can be provided on a separate fuel index table G – Final ZFW and TOW CG values in percentage of the Mean Aerodynamic Chord (%MAC). Other optional information may appear on the balance chart, according to carriers requirements: H – Index formula for DOW Index calculation (1) I – Weight deviations in galley zones and effect on balance J – Weight information (2) K– Pitch Trim scale for THS setting (1) For a given aircraft, it’s possible to start the balance calculation from the Dry Operating Index (DOI) or from the combination DOW / DOW H-arm. Thus, the index formula is only required for the second case. (2) When this information appears on the balance chart, this one can be called a “Load and Trim sheet” C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 283 L O A D I N G O P E R A T I O N S • Numerical example: DOW conditions: Weight : 123 500 kg H-arm : 33.378 m ⇐ ⇐⇐ ⇐ Data coming from the weighing report (refer to WBM) Weight deviations : Zone E : +150 kg Zone F : +150 kg Zone G : +200 kg ⇐ ⇐⇐ ⇐ Pantry adjustment in the galley zones if not included in DOW Cargo distribution : Cargo 1 : 3 500 kg Cargo 2 : 4 000 kg Cargo 3 : 7 000 kg Cargo 4 : 5 500 kg Cargo 5 : 750 kg ⇐ ⇐⇐ ⇐ Deadload distribution in the cargo holds Pax distribution : Cabin OA : 15 pax Cabin OB : 120 pax Cabin OC : 105 pax ⇐ ⇐⇐ ⇐ Passengers distribution in the cabin sections Fuel data : Takeoff fuel : 54 000 kg Fuel density : 0.79 kg/l ⇐ ⇐⇐ ⇐ Fuel on board at takeoff and fuel density C. Operational Loading Documents 284 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 123 500 33.378 105.5 12 FEB 2001 AI523 CDG Jones JFK 123 500 kg 500 kg 124 000 kg 20 750 kg 20 160 kg 164 910 kg 54 000 kg 218 910 kg 2 4 0 +150+150 +150+200 -0.247 105.2 3500 4000 7000 5500 750 15 120 105 218 910 kg 164 910 kg 29.9% 28.5% 28.5 % 3.25°UP 2 8 5 1 6 4 9 2 9 9 - 1 C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 285 L O A D I N G O P E R A T I O N S 5.2.2. Balance table a) Standard balance table In a balance table, the index corrections due to a load in a cargo compartment or passengers in a cabin section are indicated thanks to tables, instead of graphical scales as in a balance chart. The user has to start from the DOW Index and then add or subtract the different index corrections to get the ZFW Index. IATA AHM 519 gives information about the kind of information that must appear on a balance table (refer to next page): A – The type of aircraft and version B – A drawing of the aircraft layout showing : . The passenger cabin section . The position and numbering of holds and compartments C – Tabulated index corrections for each passenger cabin section D – Tabulated index corrections for each cargo compartment E – A balance diagram with shaded areas outside the forward and aft balance limits F – A balance diagram with shaded areas outside the forward and aft balance limits G – The influence of fuel on weight and balance. It can be provided on a separate fuel index table (identical to the one used with a balance chart) H – Final ZFW and TOW CG values in percentage of the Mean Aerodynamic Chord (%MAC). I – Index formula for DOW Index calculation As for the balance chart, optional information may appear on the balance table according to carriers requirements, such as the Index formula for DOW Index calculation (I). • Numerical example DOI : 105 CPT2 : 4000 kg CAB ZONE C : 105 pax ZFW Index : 105 – 8 + 19 = 116 C. Operational Loading Documents 286 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S • Balance table example B D E F C A H I G C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 287 L O A D I N G O P E R A T I O N S b) Balance table with complement of 1000 To avoid negative index corrections that could be a source of mistake, carriers sometimes prefer to use a balance table with complement of 1000. In this case, index corrections are always positive. As an example, instead of –3, the index correction would be 997 (1000-3). • Complement of 1000 - example • Numerical example DOI : 510 CPT 1 : 2000 kg CPT 4 : 1500 kg CPT 5 : 300 kg CAB OA : 4 pax CAB OB : 7 pax CAB OC : 10 pax ZFW Index : 2,514.2 The thousands figure is suppressed to obtain a final ZFW Index (514.2) consistent with the index scale. 3 C. Operational Loading Documents 288 Getting to Grips with Aircraft Weight and Balance L O A D I N G O P E R A T I O N S 5.3. EDP balance calculation methods The balance information shall be printed on EDP loadsheet or ACARS loadsheet in a specific box called “Balance and seating condition” according to the carrier requirement as per AHM 560. The system should be able to check the weight and balance limitations, and forbid the print out of the loadsheet when the limits are exceeded. • Balance information on an EDP loadsheet – Example LOADSHEET CHECKED APPROVED EDNO ALL WEIGHTS IN KILOS 02 FROM/TO FLIGHT A/C REG VERSION CREW DATE TIME CDG JFK AI0533 OOTPA C18Y264 2/9 30DEC00 1405 WEIGHT DISTRIBUTION LOAD IN COMPARTMENTS 10785 1/3830 2/6955 4/4300 PASSENGER/CABIN BAG 16905 190/ 27/ 3 TTL 220 CAB PAX CY 16/204 SOC BLKD ************************************************************************* TOTAL TRAFFIC LOAD 27690 DRY OPERATING WEIGHT 123250 ZERO FUEL WEIGHT 150940 MAX 168000 TAKE OFF FUEL 65500 TAKE OFF WEIGHT ACTUAL 216440 MAX 230000 TRIP FUEL 58600 LANDING WEIGHT ACTUAL 157840 MAX 180000 BALANCE AND SEATING CONDITIONS LAST MINUTE CHANGES DOI 105 LIZFW 118 DEST SPEC CL/CPT WEIGHT LITOW 117 MACZFW 32.8 MACTOW 30.5 STAB TO 2.2 NOSE UP BASED ON FUEL DENSITY .790 KG/LTR A16.B120.C84 CABIN AREA TRIM UNDERLOAD BEFORE LMC 13560 LMC TOTAL *********************************************************************************** BALANCE INFORMATION (AHM 050) DOW Index : 105 ZFW Index : 118 TOW Index : 117 ZFW CG : 32.8% MAC TOW CG : 30.5% MAC THS setting : 2.2º NOSE UP Fuel density : 0.79 kg/liter Cabin OA : 16 pax Cabin OB : 120 pax Cabin OC : 84 pax C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 289 L O A D I N G O P E R A T I O N S • Balance information on an ACARS loadsheet - Example LOADSHEET FINAL 1505 AI05333/30 30DEC00 CDG JFK OOTPA 2/9 ZFW 150940 MAX 168000 TOF 65500 TOW 216440 MAX 230000 TIF 58600 LAW 157840 MAX 180000 UNDLD 13560 PAX /0/16/204 TTL220 LIZFW 118 LITOW 117 MACZFW 32.8 MACTOW 30.5 ENDAI0533 BALANCE INFORMATION (AHM 050) ZFW Index : 118 TOW Index : 117 ZFW CG : 32.8% MAC TOW CG : 30.5% MAC SYSTEMS A. Cargo Systems .......................................................................... 9 1. Type of ULDs and Configuration........................................................................................... 9 1.1. History............................................................................................................................ 9 1.2. IATA identification code for Unit Load Devices (ULDs)................................................. 10 1.3. ULDs among the AIRBUS fleet .................................................................................... 14 2. Cargo Holds descriptions.................................................................................................... 19 2.1. Bulk cargo system........................................................................................................ 19 2.2. Cargo Loading Systems (CLS):.................................................................................... 21 2.3. Cargo loading system failure cases.............................................................................. 28 2.4. Additional Cargo holds related systems ....................................................................... 29 B. Fuel Systems ........................................................................... 38 1. Generalities ........................................................................................................................ 38 2. The Single-Aisle family (A318/A319/A320/A321) ................................................................ 40 2.1. Tanks and capacities ................................................................................................... 40 2.2. Fuel System ................................................................................................................. 43 2.3. CG travel during refueling ............................................................................................ 45 2.4. In-flight CG travel ......................................................................................................... 48 3. The Long-Range Family (A330/A340) ................................................................................ 49 3.1. Tanks and capacities ................................................................................................... 49 3.2. Fuel systems................................................................................................................ 52 3.3. CG travel during refueling ............................................................................................ 55 3.4. In-flight CG travel ......................................................................................................... 59 4. The Wide-Body Family (A300-600/A310) ........................................................................... 64 4.1. Tanks and capacities ................................................................................................... 64 4.2. Fuel Systems ............................................................................................................... 65 4.3. CG Travel during refueling ........................................................................................... 66 4.4. In-flight CG travel ......................................................................................................... 67 4.5. CG control system........................................................................................................ 67 C. Less Paper in the Cockpit Weight and Balance system .......... 69 1. Generalities ........................................................................................................................ 69 2. User interface – general presentation ................................................................................. 70 Getting to Grips with Aircraft Weight and Balance 1 WEIGHT AND BALANCE ENGINEERING A. Generalities.............................................................................. 75 1. Definitions........................................................................................................................... 75 1.1. Center of Gravity (CG) ................................................................................................. 75 1.2. Mean Aerodynamic Chord (MAC) ................................................................................ 75 2. Forces applied on flying aircraft .......................................................................................... 76 3. Influence of the CG position on performance...................................................................... 77 3.1. Impact on the stall speed ............................................................................................. 77 3.2. Impact on takeoff performance..................................................................................... 79 3.3. Impact on in-flight performance .................................................................................... 84 3.4. Impact on landing performance.................................................................................... 87 3.5. Summary ..................................................................................................................... 88 3.6. Conclusion ................................................................................................................... 88 4. Certified limits design process ............................................................................................ 89 4.1. Certification requirements ............................................................................................ 90 4.2. Take-off Limitations......................................................................................................91 4.3. Aircraft stability and maneuverability Limitations .......................................................... 93 4.4. Final Approach Limitations ........................................................................................... 98 4.5. Landing Limitations ...................................................................................................... 99 4.6. Limitation summary ...................................................................................................... 99 4.7. Certified limits definition ............................................................................................. 100 4.8. SUMMARY : CG ENVELOPES .................................................................................. 104 B. Weight and Balance Manual.................................................. 108 1. Section 1 : Weight and balance control............................................................................. 108 1.1. 1.00: GENERAL......................................................................................................... 108 1.2. 1.10: LIMITATIONS.................................................................................................... 109 1.3. 1.20: FUEL................................................................................................................. 111 1.4. 1.30: FLUIDS ............................................................................................................. 114 1.5. 1.40: PERSONNEL .................................................................................................... 114 1.6. 1.50: INTERIOR ARRANGEMENT ............................................................................ 115 1.7. 1.60: CARGO............................................................................................................. 115 1.8. 1.80: ACTIONS ON GROUND ................................................................................... 117 1.9. 1.90: Examples .......................................................................................................... 117 2. Section 2 : Weight Report................................................................................................. 118 2 Getting to Grips with Aircraft Weight and Balance WEIGHT AND BALANCE ENGINEERING C. Balance Chart Design............................................................ 121 1. Moment and Index definitions ........................................................................................... 121 1.1. Moment...................................................................................................................... 121 1.2. Index.......................................................................................................................... 123 2. Index variation calculation (∆Index) .................................................................................. 125 2.1. ∆Index for one item .................................................................................................... 125 2.2. ∆Index for additional crew member ............................................................................ 125 2.3. ∆Index for additional weight on the upper deck .......................................................... 126 2.4. ∆Index for passenger boarding................................................................................... 127 2.5. ∆Index for cargo loading............................................................................................. 128 2.6. ∆Index for fuel loading................................................................................................ 130 3. operational limits determination ........................................................................................ 135 3.1. Calculation principle ................................................................................................... 135 3.2. Margins determination method ................................................................................... 135 3.3. Inaccuracy on initial data (DOW and DOCG) ............................................................. 138 3.4. Inaccuracy on items loading on board the aircraft (passengers, cargo, fuel) .............. 140 3.5. Inaccuracy due to CG computation method................................................................ 162 3.6. Item movements during flight impacting the aircraft CG position ................................ 167 3.7. Total operational margins determination .................................................................... 175 3.8. Takeoff, Landing, In-Flight operational limits determination........................................ 176 3.9. Zero Fuel limit determination...................................................................................... 178 4. Balance Chart Drawing principle....................................................................................... 181 4.1. ∆index scales or tables for loaded items .................................................................... 182 4.2. Operational limits diagram.......................................................................................... 184 5. The AHM560 .................................................................................................................... 186 5.1. Generalities................................................................................................................ 186 5.2. PART A: COMMUNICATION ADDRESSES............................................................... 186 5.3. PART B: GENERAL INFORMATION ......................................................................... 187 5.4. PART C: AIRCRAFT DATA........................................................................................ 187 5.5. PART D: LOAD PLANNING DATA............................................................................. 189 D. Load and Trim Sheet software .............................................. 191 1. Introduction....................................................................................................................... 191 2. Objectives......................................................................................................................... 191 3. Software description ......................................................................................................... 192 3.1. Unit system: ............................................................................................................... 192 3.2. Aircraft modifications:................................................................................................. 192 3.3. Aircraft configurations: ............................................................................................... 193 3.4. Cabin layout: .............................................................................................................. 194 3.5. Operational margins customization ............................................................................ 195 Getting to Grips with Aircraft Weight and Balance 3 LOADING OPERATIONS A. Loading Generalities.............................................................. 201 1. Load control...................................................................................................................... 201 1.1. Loading constraints .................................................................................................... 201 1.2. Load control organization and responsibilities ............................................................ 201 1.3. Load control qualification............................................................................................ 204 2. Aircraft Weight.................................................................................................................. 205 2.1. Regulation.................................................................................................................. 205 2.2. Aircraft Weighing........................................................................................................ 206 3. Passenger weight ............................................................................................................. 207 3.1. General ...................................................................................................................... 207 3.2. Survey........................................................................................................................ 207 4. Loading Operations .......................................................................................................... 210 4.1. Preparation before loading ......................................................................................... 210 4.2. Opening/Closing the doors......................................................................................... 215 4.3. On loading ................................................................................................................. 216 4.4. Off loading ................................................................................................................. 217 5. Loading Limitations........................................................................................................... 218 5.1. Structural limitations and floor panel limitations.......................................................... 218 5.2. Stability on ground – Tipping...................................................................................... 223 6. Securing of loads.............................................................................................................. 225 6.1. Introduction ................................................................................................................ 225 6.2. Aircraft acceleration ................................................................................................... 225 6.3. Tie-down computation................................................................................................ 227 B. Special Loading ..................................................................... 241 1. Live animals and perishable goods................................................................................... 241 1.1. Generalities................................................................................................................ 241 1.2. Live animals transportation ........................................................................................ 243 1.3. Perishable goods ....................................................................................................... 246 2. Dangerous goods ............................................................................................................. 249 2.1. Responsibility............................................................................................................. 249 2.2. References................................................................................................................. 249 2.3. Definitions .................................................................................................................. 249 2.4. Identification............................................................................................................... 250 2.5. Classification.............................................................................................................. 250 2.6. Packing ...................................................................................................................... 254 2.7. Marking and labeling .................................................................................................. 255 2.8. Documents................................................................................................................. 256 2.9. Handling and loading ................................................................................................. 258 2.10. Special shipments .................................................................................................... 259 4 Getting to Grips with Aircraft Weight and Balance ................................................... 263 1.............................................LOADING OPERATIONS C......................................... Manual loadsheet....................................... Loadsheet.....................3....... Load Information Codes .......... 264 2....... Loading Instruction / Report (LIR)...........................3........................... 274 4.................................................... 280 5................. ACARS loadsheet ....................................................... Container/Pallet distribution message (CPM) ................................ Codes used for loads requiring special attention ................1...................... 273 4.................................................................................. Introduction .......................... 278 4....................... ULD Load volume codes ............................. Balance calculation methods ........ 280 5.........2.......................... 280 5..............................................................................................................1..............3.............................. EDP LIR.............2......... EDP Loadsheet.............. Operational Loading Documents ................................................ 263 1.......................... Introduction ....... 263 1..................................................................3.................................. 269 3.......................... EDP balance calculation methods 288 Getting to Grips with Aircraft Weight and Balance 5 .......................... 273 4..........................................................................2............ 271 4.............2.................1............................ 263 1....... 265 2...........1.................................................4.................................................................................................. 279 5.. Manual LIR 266 2.......................................... Manual balance calculation method ................. Load and volume information codes .. Introduction 265 2....................... . considering that the cargo area was too great for it to be loaded manually.A. the A300 was originally designed to accommodate. On the single aisle family two cargo loading solutions are proposed to the operators either manual bulk loading or semi-automatic. electrically powered cargo loading system. the Unit Load Devices that were already standardized at that time for the B747. As an introduction the first paragraph is dedicated to Unit Load Devices description. The lower deck of the airplane is dedicated to passenger luggage as well as additional freight transportation. CARGO SYSTEMS SYSTEMS CARGO SYSTEMS INTRODUCTION Airbus aircraft are designed for passenger civil air transport with a passenger cabin on the upper deck. The following chapter describes the cargo loading areas on Airbus aircraft and the systems related to cargo holds. This solution was later used for to all the other longrange programs. electrically powered cargo loading system accommodating Unit Load Devices derived from the larger aircraft ULDs. Getting to Grips with Aircraft Weight and Balance 7 SYSTEMS . So at the end of the 60’s. with a semi-automatic. . 1. CARGO SYSTEMS 1. NAS3610 only considers the ULD baseplate. the lower-deck capacity of the 747 was too great for it to be loaded manually. introduced the 767. each unit occupying half the width of the compartment floor. which first flew in 1981. The baseplate dimensions of the half-width container were set at 60. Airbus does not differentiate between so-called certified or non-certified containers. was designated NAS3610. airframe manufacturers. Baggage and cargo had to be accommodated in Unit Load Devices (ULDs). therefore. There are a variety of different contours that may be attached to any one baseplate size. The 747 was originally designed to accommodate the 96in square cross-section of the ISO standard ‘marine’ containers on the main deck. although many of the ULD sizes in use are ‘standard’ in terms of certain critical dimensions. Getting to Grips with Aircraft Weight and Balance 9 SYSTEMS . The document was approved by the Federal Aviation Administration (FAA) in 1969 and entitled: minimum Airworthiness requirements and test conditions for Certified Air Cargo Unit Load devices. It is the responsibility of the owner of an aircraft ULD to have provisions for the maintenance of such units to the effect that they are kept in an airworthy condition. Although NAS3610 is an airworthiness certification document. incompatibilities do still exist and many different ULD types are in service. drafted with input from the major U. Most carriers at that time used 88in x 125in pallets on freighter aircraft. the new baggage containers were smaller than cargo containers and were loaded in pairs. which determined the overall shape and size of the fuselage.5in.A. which had previously only been used for freighter aircraft. The basic reference document for ULD base sizes is a National Aerospace Standard produced by the Aerospace Industries Association of America. to be able to accept the 125in dimension across the width of the lower deck. Then the lower deck height dictated the maximum height for ULDs (64in). unaccountably. Boeing then. The space remaining in the lower deck. the fact that it reflects mandatory requirements and details the baseplate dimensions of all ULDs types dictate that all ULD standards should refer to it.4 x 61. This document. however the container has to fulfil the same requirements as a certified container. in accordance with the requirements of federal Aviation Regulation-Part25 (FAR25)-Airworthiness Standards: Transport Category Aeroplanes. The 747s lower-deck system was required. It is not required that a container actually undergoes a certification process. The primary objective was to provide requirements designed to ensure the ability of ULDs and their in-aircraft restraint-systems to contain their load under the influence of in-flight forces. For ease of handling. the air transport industry faced a dramatic change of ground-handling culture. Having been of such service to the industry in developing a ‘standard’ for lower deck ULD equipment. TYPE OF ULDS AND CONFIGURATION 1. after satisfying the main deck requirement determined the basic dimensions and shape of the lower-deck containers. CARGO SYSTEMS A. History When the first Boeing 747 went into service in 1970. which used several completely different sizes of ULD. In fact. With this background of evolution and airframe manufacturer influence.S. pallet/net/non-structural igloo assembly. pallets. The IATA Identification Code consists in nine characters composed of the following elements: Position Type description 1 ULD Category 2 Base Dimensions 3 Contour and Compatibility 4. Taking into account all the characteristics corresponding to a particular ULD has therefore developed an identification Code.2 and 3) • Position 1 Position 1 is used to describe the general type of the unit considering only the following characteristics: − Certified as to airworthiness or non-certified. CARGO SYSTEMS SYSTEMS 1. insulation or thermal control or not fitted for refrigeration.5. nets. − Fitted with equipment for refrigeration. Code Letter A D F G J M N P R U H K V X Y Z ULD Category Certified aircraft container Non-Certified aircraft container Non-Certified aircraft pallet Non-Certified aircraft pallet net Thermal non-structural igloo Thermal non-certified aircraft container Certified aircraft pallet net Certified aircraft pallet Thermal certified aircraft container Non-structural container Horse stalls Cattle stalls Automobile transport equipment Reserved for airline internal use Reserved for airline internal use Reserved for airline internal use 10 Getting to Grips with Aircraft Weight and Balance .6 and 7 Serial number 8 and 9 Owner/Registrant Only the three first letters are necessary to identify the ULD. The purpose of the following paragraph is to explain quickly the method of ULD marking and numbering. • IATA Identification Code The Identification Code gives each unit an individual identification and allows the easy exchange of the information contained in the marking of units. • TYPE CODE (Positions 1.A. − Also considering specific units: containers.2. IATA identification code for Unit Load Devices (ULDs) There is a large number of ULDs in operations today. − Structural unit or non-structural. insulation or thermal control. This Code contains essential data to describe each ULD and for further technical information the reference is the IATA ULD Technical Manual. A.4 x 125 in 2438 x 3175 mm 96 x 125 in 1562 x 2438 mm 61.5 x 96 in 1198 x 1534 mm 47 x 60.25 in 2438 x 12192 mm 96 x 480 in 1534 x 1562 mm 60.4 x 61.5 in 2438 x 9125 mm 96 x 359. CARGO SYSTEMS • Position 2 This position makes reference to the Base Dimensions of the ULD.4 in 1534 x 2438 mm 60.5 in 1534 x 3175 mm 60.75 in 2438 x 6058 mm 96 x 238.4 x 96 in 2438 x 4938 mm 96 x 196 in Miscellaneous sizes largest dimension between 2438 mm and 3175 mm (between 96 in and 125 in) Miscellaneous sizes largest dimension lower than 2438 mm (96 in) Miscellaneous sizes largest dimension above 3175 mm (125 in) Getting to Grips with Aircraft Weight and Balance 11 SYSTEMS . Series A B E F G H J K L M N P Q R X Y Z Base dimensions (and compatible nets when applicable) length width length width 2235 x 3175 mm 88 x 125 in 2235 x 2743 mm 88 x 108 in 1346 x 2235 mm 53 x 88 in 2438 x 2991 mm 96 x 117. A.Forkliftable M 92 in(2337mm) 79 in(2007mm) 64in (1626mm) E/N 46in (1168mm) G C C 2. Here are the main contours and their letters. 48in (1219mm) A/B 90in (2286mm) M A .Non-Forkliftable B . CARGO SYSTEMS SYSTEMS • Position 3 The Position 3 corresponds to the type of contour and describes if the ULD is forklift compatible or not.25 in (108mm) 12 Getting to Grips with Aircraft Weight and Balance 46in (1168mm) U . The loading contours have been sequentially numbered and the individual aircraft ULDs are coded and marked according to the type of aircraft in which they can be carried.12 in(54mm) E-Non-Forkliftable N-Forkliftable G 93 in(2362mm) 80 in(2032mm) 96 in(2438mm) 64in (1626mm) 96in (2438mm) F A/B H U/F/H 2. A full description of the aircraft contours is contained in the IATA ULD Technical Manual.12 in(54mm) or 4. A. CARGO SYSTEMS 62.5 in(1588mm) 41.3 in (389mm) Z 64 in(1626mm) 82 in(2083mm) K Z/K Getting to Grips with Aircraft Weight and Balance 13 SYSTEMS .3 in (1049mm) 15.5 in(1588mm) 64 in(1626mm) P P 62. 42 m3 .4 in (1534 mm) 60.4 m3 .5 in (1562mm) 61.5 in (1562mm) 61.A.7 m3 .109 ft³ 3.9 m3 .5 in (1562mm) 125 in (3175 mm) 61.123 ft³ (contour P) Height Vol.5 in (1562 mm) 64 in (1626mm) 64 in (1626mm) 64 in (1626mm) 46 in (1168mm) 10.385 ft³ (contour P) 14.4 in (1534 mm) Width 125 in (3175 mm) 125 in (3175 mm) 61.5 m3 .9 m3 .4 in (1534 mm) 60.45 in (1016-1143mm) 64 in (1626mm) 64 in (1626mm) 64 in (1626mm) Height Typical Volume (without shelves) 4.4 in (1534 mm) 60.6 m3 . CARGO SYSTEMS SYSTEMS 1.5 in (1562 mm) 61.4 in (1534 mm) 60.5 in (1562mm) 61.4 in (1534 mm) Width 61.3.473 ft³ (contour F) 7. 14 Getting to Grips with Aircraft Weight and Balance .314 ft³ 2.5 in (1562mm) 47 in (1194 mm) 96 in (2432 mm) 96 in (2432 mm) 64 in (1626mm) 46 in (1168mm) 46 in (1168mm) 64 in (1626mm) 64 in (1626mm) 40 .1 m3 .4 in (1534 mm) 60.515 ft³ (contour F) 10 m3 .96 ft³ 120 ft³ 202 ft³ 245 ft³ PALLETS Base Dimension ATA IATA Length LD9 standard LD7 PMx PAx (A2) PLx PKx 96 in (2438 mm) 88 in (2235 mm) 60.353 ft³ (contour P) 13.2 m3 .3 m3 .151 ft³ 3.254 ft³ (contour F) 3.166 ft³ 8.4 in (1534 mm) 39.4 in (1534 mm) 60.68 m3 – 130 ft³ 4.75 in (1010mm) 60. ULDs among the AIRBUS fleet ULD Type CONTAINERS Base Dimension ATA IATA Length LD3 LD3-46 standard LD3-46W LD1 LD6 LD3-40/45 LD2 option LD4 LD8 AKE (V3) AKG AKH AKC (V1) ALF (W3) H DPE DQP DQF 60.4 in (1534 mm) 60. ****option : for A340-500 equipped with 7 frames Rear Center Tank (RCT) Getting to Grips with Aircraft Weight and Balance 15 SYSTEMS . **option : the basic version is designed for bulk loading.A. CARGO SYSTEMS ULD Number of ULD per cargo hold FWD/AFT/BULK Max weight A319 A320 A321 A310 A300600 A330200 A330300 A340300 A340A340A340-500 200 600 18/12 24/18 18/10**** 18/12 24/18 18/10**** 9/6 9/5**** 12/9 ATA/ A318 IATA LD3 / AKE (V3) LD346 / AKG LD346W / AKH LD1 / AKC (V1) LD6 / ALF (W3) LD340/45 /H LD2 / DPE option LD4 / DQP LD8 / DQF PMx Pax (A2) PLx 8/6/1* 12/10/1* 14/12/1* 18/14/1* 14/12/1* 3500lb (1587kg) 2/2**/0 3/4**/0 5/5**/0 8/6/1* 12/10/1* 14/12/1* 18/14/1* 14/12/1* 2500 lb (1134kg) 2/2**/0 3/4**/0 5/5**/0 4/3/1* 6/5/1* 7/6/1* 9/7/1* 7/6/1* standard 2500lb (1134kg) 4/3/0 6/5/0 7/6/0 9/7/0 7/6/0 9/6 9/5**** 9/6 9/5**** 12/9 3500lb (1587kg) 4/3/0 0/1** 1660lb (753kg) 0/8*** 0/10*** 0/8*** 6/5/0 7/6/0 9/7/0 7/6/0 12/9 7000lb (3174kg) 2700lb (1224kg) 0/4*** 0/4*** 0/5*** 0/5*** 0/4*** 0/4*** 6/4 6/3**** 6/4 6/3**** 9/6 9/5**** 5400lb (2449kg) 5400lb (2449kg) 3/0 4/0 4/4 6/4 5/4 8/6 11250lb (5103kg) 3/0 4/0 4/4 6/5 5/4 8/6 PALLET 10200lb (4626kg) 4/3/0 6/5/0 7/6/0 9/7/0 7/6/0 12/9 7000lb (3174kg) PKx 2/2 3/4 5/5 8/6 12/10 14/12 18/14 14/12 18/12 24/18 18/10**** 3500lb (1587kg) *option : additional container in bulk cargo compartment. ***option : eight (or ten) containers plus four LD3 in aft compartment. Aircraft: A310.5 (156 in 2mm ) 60.4 m) 34m (15 CONTAINER ALF IATA ULD Code: ALF.25m³) Certified MGW limit: 1660 lb (753 kg) 96 in (2438m m) CONTAINER AKE IATA ULD Code: AKE Classification ATA: LD3 Also known as AVA. Aircraft: A310.4 in ) mm (1534 *46 in (1168 mm) 61. Volume: 159 to 173 ft³(4.5 in (1562 mm) 60. Classification ATA: LD6 Aircraft: A310. A300.1 to 4.4 in ) mm (1534 NB: * means that. DVE. for those two containers.A.47m³) Weight limitations: 3500 lb (1587 kg) 79 in (2007mm ) 45 in (1168 mm) 61. DVP.1m³) Weight limitations: 2500 lb (1134 kg) 79 in (2007m m) CONTAINER AKH IATA ULD Code: AKH Classification ATA: LD3-46W Also known as DKH. AVC. Some airlines prefer the 45 in container. 16 Getting to Grips with Aircraft Weight and Balance . A330. Volume: 316 ft³(8. Aircraft: A320 family and interlining Volume: 127 ft³(3.75 ) 10mm (10 64 in (1626mm) 61. DVA.5 (1562 in mm) 60.4 in ) mm (1534 64 in (1626mm) 61.9m³) Weight limitations: 7000 lb (3175 kg) 160 in (4064m m) CONTAINER AKC IATA ULD Code: AKC Classification ATA: LD1 Also known as AVC. AVD. A340.4 in ) mm (1534 Additional CONTAINER A319 IATA ULD Code: H Classification ATA: LD3-40/45 Aircraft: A319 Volume: 80 ft³(2. CARGO SYSTEMS SYSTEMS CONTAINER AKG IATA ULD Code: AKG Classification ATA: LD3-46 Aircraft: A320 family and interlining Volume:110 ft³(3. AVB. A340. A330. A300. A340. A300.5 (156 in 2mm ) in 60.XKG.9m³) Weight limitations: 3500 lb (1587 kg) 94 in (2337 mm) 64 in (1626 mm) 125 (317 in 5mm ) 60.6m³) Weight limitations: 2500 lb (1134 kg) 96 in (2438m m) *46 in (1168 mm) 61.5 to 4. this dimension varies between 44 in and 46 in. XKS. Volume: 145 to 158 ft³(4. AVK. AVK. A330. AVJ. (156 5 in 2mm ) in 39. DLE.A. Classification ATA: LD8 Also known as ALE. A340. PAG. PAX. ALN. P1G.4 in ) mm (1534 Getting to Grips with Aircraft Weight and Balance 17 SYSTEMS 64 in (1626mm) 64 in (1626mm) 64 in (1626mm) 46 in (1168mm) . P1A. P6A. Aircraft: A310. DLF. P6Q. PAJ. PMC. P1D.4 mm) (1534 125 (317 in 5mm ) 88 in ) mm 2235 ( CONTAINER DQF IATA ULD Code: DQF. Volume: 407 ft³(11. A340. PQP. P1C.5m³) Weight limitations: 10200 lb (4626 kg) 64 in (1626mm) 47 in (1194 mm) in 60.7m³) Weight limitations: 5400 lb (2449 kg) PALLET PKx IATA ULD Code: PKx Volume: 85 ft³(2.4 m) 534m (1 125 (317 in 5mm ) 96 in ) 8mm (243 CONTAINER DQP IATA ULD Code: DQP Classification ATA: LD4 Volume: 202 ft³(5. Volume: 245 ft³(6.5m³) Weight limitations: 11250 lb (5103 kg) 64 in (1626 mm) 96 in (1194 mm) in 60. A330.4m³) Aircraft: A320 family Weight limitations: 2500 lb (1134 kg) Certified MGW limit: 3500 lb (1587 kg) 96 in (243 8 mm ) in 60. PMP. Aircraft: A330.5 in (1562m m) PALLET PAx IATA ULD Code: Pax Classification ATA: LD7 Also known as PAA. DQP. PMA. Also known as APA. A300. Volume: 372 ft³(10. A330. DPA.4 m) 34m (15 61. A340.4m³) Weight limitations: 2700 lb (1224 kg) 61.5 (1562 in mm) 60. Volume: 120 ft³(3. A300. CARGO SYSTEMS CONTAINER DPE IATA ULD Code: DPE Classification ATA: LD2.9m³) Weight limitations: 5400 lb (2449 kg) 125 in (3175 m m) PALLET PMx IATA ULD Code: PMx Classification ATA: LD9 Also known as P6P. PAP. Aircraft: A310. . Getting to Grips with Aircraft Weight and Balance 19 SYSTEMS . There is also a divider net separating AFT and BULK cargo holds. 2. The cargo holds position arrangement depends on the aircraft fuselage length. CARGO SYSTEMS 2. FWD and AFT holds are divided into 1 or 2 compartments. CARGO HOLDS DESCRIPTIONS All Airbus aircraft lower decks are divided into 3 cargo holds : forward (FWD). 2. AFT and BULK. They have fixed locations in each cargo hold and dedicated attachment points on the ceiling and side-wall linings and on the floor panels. Cargo components a) Partition nets These nets are used for cargo loading areas separation.1. Bulk cargo system For the A320 family aircraft the basic way to load cargo is to load it in bulk.A. each compartment being made of several loading positions defining the position of each type of ULD or the position of bulk cargo loads.1.1. For any Airbus aircraft the most rear cargo hold (BULK : compt 5) is also loaded in bulk. This divider net has to be linked with a tarpaulin. These holds are equipped with adequate cargo and lining components. They are located on the ceiling and side-wall linings and on the floor panels. which due to their geometry or weight may damage the panel.2. c) Attachment point Attachment points are used to fasten the nets. 2. d) Tie-down point Tie-down points are used to restraint cargo item(s) movement in the cargo hold. Lining components a) Floor panel b) Side wall lining c) Ceiling d) Partition wall Each panel has a defined maximum static area load. These loads are not exceeded if the maximum loads per position and per holds are not exceeded and if loads. are tied down at loading.1. CARGO SYSTEMS SYSTEMS b) Door net These nets are used to delimit the entrance door area which must remain unloaded.A. 20 Getting to Grips with Aircraft Weight and Balance . Attachment points on the floor panels that are not used for nets fastening can be used for load restraint. Attachment points in the side-wall and ceiling linings are for nets fastening only. power drive and control component. The cargo loading system is equipped with rollertrack mounted self-lifting electrical Power Drive Units (PDU) installed for the lateral and longitudinal movement of ULDs and controlled by a joystick located in the doorway. Cargo Loading Systems (CLS): The 2-aisle aircraft family is equipped with a semi-automatic. they allow multidirectional and low friction movements of ULDs in the cargo door area. For A320 family. except for the A318. CARGO SYSTEMS 2.2.1. The cargo loading system allows manual loading and offloading of the ULDs if the power drives are inoperative for any reason.A. The following paragraphs provide detailed information about conveyance components. The ballmats and strips are equipped with ball transfer units installed in a framework. 2. Ballmats and Ball Transfer units in entrance area of A330/A340 Getting to Grips with Aircraft Weight and Balance 21 SYSTEMS . Conveyance components: a) Ballmats and Ball Transfer units in entrance area: Ballmats and ball strips are installed in the forward and aft cargo door entrance area. This cargo loading system is compatible with ULDs designed to meet the class II requirements of the specification NAS3610 and provides individual ULD baseplate restraint. electrically powered cargo loading system in the FWD and AFT cargo holds. It offers a real flexibility for loading as any position can be loaded or remain empty. guides and restrains. ULDs which do not fit into the restraint system due to their geometry can be loaded but they must be handled in such a manner that neither the ULD nor the items loaded on it will endanger the aircraft during the whole flight.2. Locking and unlocking of ULDs inside the cargo compartments is carried out manually. Simultaneous loading and offloading of the FWD and the AFT holds is possible provided that the stability criteria are met. an option is available to have the cargo loading system installed. “Self . It provides a towing force. a gear drive and a rubber coated roller.2.Lift” type 22 Getting to Grips with Aircraft Weight and Balance . In these roller tracks braking rollers are also installed to prevent inadvertent ULD movement. equipped with transport rollers. the roller tracks are additionally equipped with power drive units and proximity switches below the XZ-latches allowing powered transportation of ULDs. CARGO SYSTEMS SYSTEMS b) Roller tracks: The roller tracks are installed in longitudinal direction. the drive roller lowers automatically to its rest position. mounted on a rolling axle. sufficient to drive the ULDs in different directions. At certain position. The roller tracks are extruded profiles. When the PDU is switched off. Transport roller Roller track 2.A. used for longitudinal transport of ULDs.2. Power drive and control components: a) Power drive units: The Power Drive Unit (PDU) consists of an electrical motor. “Spring . PDU Drain outlet Roller track PDU sensor Ball mat PDU. It is used to move the ULDs in longitudinal and lateral direction.lift” type Outside ball mat PDU. endstops and XZ-latches. 3 mm below system height. All PDUs are activated via signal from the control system. CARGO SYSTEMS b) Control components and control panel: Loading and offloading with the lower deck cargo loading system is managed by control panels located at FWD and AFT cargo doors. On A340-500 and A340-600 aircraft an additional joystick is installed on the roof of the entrance area. − a switch at each door sill latch interrupting power supply for the CLS each when the latch is raised and preventing door operations when the latch is lowered.A. that are equipped with a power ON-OFF switch to activate the CLS and a joystick to determine the direction of movement of the PDUs. Additional joystick Getting to Grips with Aircraft Weight and Balance 23 SYSTEMS . In order to avoid any unexpected or dangerous ULD movement in the cargo hold some limitation systems are available : − limit switches below the XZ-latches stopping the PDU power when the ULD has reached its limit. From this joystick it is possible to control the all PDUs except those in the ballmat area. CARGO SYSTEMS SYSTEMS 2. 24 Getting to Grips with Aircraft Weight and Balance . a hydraulic damper delays the Y-latch raising to allow ULD unloading. − a guide roller which is used to transfer of ULDs between the loader and the ballmat area.A. − an overrideable Y-latch which prevents inadvertent roll out of ULDs during loading and off-loading. returning to the raised position once the ULD has passed over. which allows to latch the ULDs positioned in the door entrance area. YZ-latch lowered YZ-latch in up position The overrideable Y-latches are spring loaded and operated automatically or manually.3. Each door sill latch consists of: − a YZ-latch. to prevent inadvertent roll out. It can be lowered by pressing a red lever at the side of the unit and can be raised by being pulled up by hand. the Y-latch has to be lowered manually by means of a handle located on the cargo loading system control panel.2. Guide roller Overrideable Y-latch YZ-latch The YZ-latch is operated manually. When the handle is pushed down. They are overrideable in loading direction. Guides and restraints: a) Door sill: Door sill latch units are installed in the FWD and AFT cargo door areas. Each lever of the door sill latch units is electrically monitored by a limit switch to ensure that the cargo door cannot be closed when the YZ-latch is in its lower position and that the CLS is not powered closed when the YZ-latch is in its up position. Before ULD offloading. Tie down point Fixed YZ-latch Optional Continuous Side Guides Tie down point Fixed YZ-latch Getting to Grips with Aircraft Weight and Balance 25 SYSTEMS . Entrance guides AFT door Entrance guides FWD door Retractable Y-guides c) Fixed YZ-latches and side guides opposite of cargo door: The fixed YZ-latches serve to guide in X-direction and to lock ULDs in Y. Entrance guides system is made of guides acting in different directions : − a mechanical Z-guide is installed for guidance of ULD baseplates under the endstops.and Z-direction. Each YZ-latch is equipped with a tie-down point. which provides sufficient clearance between ULD’s baseplate and the door frame during loading and offloading. To transport the ULDs to their final position those guides have to be unlocked by operating a toggle switch on the entrance control panel. designed to a maximum load of 2000 lbs (890daN) or 4000 lbs for A340-500 and A340-600 in any direction. − retractable Y-guides prevent the ULD’s from turning while entering the compartment. A vertical guide roller is installed in the YZ-latch. CARGO SYSTEMS b) Entrance guides: The door entrance guides provide a correct guidance on the ballmat during loading or offloading of ULDs and prevent impact to the doorframe. Additional side guides are basically installed opposite of each cargo door to align ULDs and optional continuous side guides are installed all along the cargo holds.A. − a spring loaded Y-guide is installed with a guide roller. These latches are located at each frame on both sides of the cargo compartments. CARGO SYSTEMS SYSTEMS d) Overrideable YZ-latches (A310. They are located in the entrance area of AFT and FWD holds. A300. Overrideable Y-guide 26 Getting to Grips with Aircraft Weight and Balance . A340): Overrideable YZ-latches. The two latch claws are spring loaded so they raise again when the ULD has moved on. also known as “butterfly”.A. A330. Overrideable YZ-latches e) Overrideable Y-guide (splitter): The overrideable Y-guides are used to separate half-size ULDs during loading and offloading. are provided to lock half-size containers in Yand Z-direction. When loading ULDs they can be lowered manually by foot beneath the level of the cargo loading system then when half size containers are loaded they can be pulled up using the control panel joystick in order to separate the ULDs. During loading of full size containers the latches are overridden. These latches are attached to the structure at aircraft centerline. and Z-direction. Getting to Grips with Aircraft Weight and Balance 27 SYSTEMS . Depending on the cargo hold configuration single. CARGO SYSTEMS f) XZ-latches: The XZ-latches are used to lock the ULDs in X.and Z-direction. double or triple latches may be installed in order to accommodate any kind of ULD loading. These switches serve to cut off the power supply of the associated PDUs when the applicable latch is in the locked (up) position and to restore PDU power supply when the latch is in lowered position. Limit switches are installed underneath some of the XZ-latches. Single latch Double latch Triple latch g) Endstops: The fixed XZ-endstops at the extremities of each cargo hold are used to lock ULDs in the X. The latch is locked by hand by pulling the pawl upwards.A. They are spring loaded and operated manually. To unlock/lower the latch the pawl marked “Press to unlock” needs to be pressed this can be achieved by foot pressure. They are fitted to the roller tracks. Malfunctioning equipment should be replaced as soon as possible. CARGO SYSTEMS SYSTEMS 2. some limitations in the allowed cargo weight per position may appear.10.A. Failure of a latch may require weight reduction of the ULD forward and aft of the latch of LH and RH of the latch. tie down points. Example : A330-200 : In case of XZ-latch failure between position 13L and 21L.3. Cargo loading system failure cases In case of failure or malfunctions of some of the cargo loading system equipments: nets. ULD weight must be reduced to 0 kg on both position. The WBM details these different limitations in chapter 1. In case of malfunctioning ULD’s and aircraft structure. …. latches. 28 Getting to Grips with Aircraft Weight and Balance . 23 x 1.68 x 1.8x50.5 in) 1.70 x 2.82 m (48.6x71.4.5 in) A310/A300 1.82 m (48.5 in) A319 1.95 m (34 x 37 in) 0.28 m (48.4 in) Getting to Grips with Aircraft Weight and Balance 29 SYSTEMS .95 m (25x37.23 x 1.24 x 1.23 x 1.6x50.72 m (66.4.4 in) 0.1x107 in) BULK DOOR No door No door 0.68 x 2.81 x 0.6x71.23 x 1.5 in) 1.3x71.82 m (48. Additional Cargo holds related systems 2.82 m (48.23 x 1.1x37.70 m (66.The forward and the aft cargo doors open to the outside and the bulk cargo door opens to the inside.88 x 0.5 in) 1.5 in) A321 1.1.A.23 x 1.2 x 1.9x106 in) AFT DOOR 1. one for the aft cargo compartment and one for the bulk compartment.6x71.70 m (66.6x71.3 in) 1. However the shorter A318 and A319 do not have the bulk cargo door.5 in) 1.5 in) A320 1. CARGO SYSTEMS 2.64 x 0.95 m (25.82 m (48.95 m (32 x 37 in) 0.82 m (48. Cargo hold doors In most Airbus aircraft there are three cargo doors: one for the forward compartment.6x71.8x106 in) A330/A340 1. Bulk Cargo Door CLEAR OPENING DIMENSIONS A318 FWD DOOR 1.6x71.81 m (66.69 x 2.64 x 0.28 m (48. 2. sidewalls and floors of the cargo compartment have fire and impact resistant linings complying with “JAR/FAR 25 Amendment 60”. The sidewalls and partitions are equipped with rapid decompression panels. The installed linings and floor panels are designed for the following: − Handling loads from loading personnel. − Surface finish in light color. CARGO SYSTEMS SYSTEMS 2. The floor panels and the linings are of sandwich type. prepreg layers and protection foil or metal sheet. in case of “blow out” the frame of the decompression panel brakes to allow decompression panel displacement. − Low smoke and toxicity requirements. Lining and decompression (All Airbus aircraft): The ceiling. Decompression panels In case of “blow in” spring loaded snappers are pushed back.A. − Rapid decompression requirements according to FAR/JAR. Each decompression panel is enclosed within a frame and is held in place by decompression assemblies. − Flammability requirements according to FAR/JAR. − Quick release features necessary for accessibility. manufactured from honeycomb.4. “Blow out” case “Blow in” case 30 Getting to Grips with Aircraft Weight and Balance . − Leak proof requirements for class C compartments according to FAR/JAR. which contains a sponge filter element. Hoses are connected to the drain outlets.4. For the lighting of the loading area. 2.3.A. Drain funnels are installed in the roller tracks. Cargo compartment lighting (All Airbus aircraft): A separate lighting system is installed in each cargo compartment. All lights are manually controlled by means of switches. with drain valves.4. The loading area light is sufficient to allow reading of labels on the ground loading equipment. leading to the bilge area. Getting to Grips with Aircraft Weight and Balance 31 SYSTEMS . numerous drain-outlets are provided in forward and aft cargo compartments and in the bulk compartment floor. acting as a coarse filter. The drain outlets consist of a mounting housing. placed near to the cargo door. which is provided. CARGO SYSTEMS 2. Drainage (All Airbus aircraft): To prevent accumulation of water in the cargo compartments. a spotlight is installed in each door ceiling area. Each cargo hold is provided with a minimum light level of 50 lux at the hold floor. The control switch is installed adjacent to the cargo door for the respective compartment.4. in sumps and in the floor in front of slushing dam. On request. The extracted air from the bulk cargo compartment is passed under the bulk compartment floor to provide floor heating.5.A. In the bulk cargo compartment. CARGO SYSTEMS SYSTEMS 2. Air Extraction Air Extraction Fan Fan BULK Overboard Inlet Isolation Inlet Isolation Valve Valve ELECTRICAL FAN HEATER Cabin Ambient Air 32 Getting to Grips with Aircraft Weight and Balance . Heating and ventilation a) in bulk cargo compartment (A310/A300/A330/A340): Cabin ambient air is supplied to the bulk cargo compartment through a distribution duct along the left-hand side of the compartment. The air is extracted from the bulk compartment by an electrical fan through vents near ceiling on the right-hand side.4. an electrical heater can heat the air. isolation valves are fitted in the inlet and outlet ducts to isolate the cargo compartment in case of smoke warning. To decrease the compartment temperature. In the bulk cargo compartment. FWD Overboard Cold air valve Cold air valve Trim air valve Trim air valve (hot air supply) (hot air supply) Cabin Ambient Air Cabin Ambient Air An additional option is available which ensures proper ventilation in the bulk and main cargo compartments during ground time when respective cargo doors are open. CARGO SYSTEMS b) in FWD and/or AFT cargo compartment (all aircraft. cold air valve are automatically closed and the extraction fan is switched OFF. Temperature control is provided on top of the ventilation by adding cold or hot air respectively from the packs or hot air manifold. the cabin ambient air can be mixed with cold air from the packs via a cold air valve. This valve has three positions to adjust the quantity of cooled conditioned air. the following aircraft conditions and activities are necessary: − Packs running − Forward cooling selector in cockpit overhead panel in "NORM" position. Getting to Grips with Aircraft Weight and Balance 33 SYSTEMS . the isolation valves. It is possible to select temperatures within the range of 5 DEG C and 25 DEG C (41 DEG F and 77 DEG F). The hot air supply is controlled by a trim valve which regulates the temperature in the compartment. A cockpit temperature selector and a cockpit cooling mode selector control temperature. this option uses the same ventilation as in flight nevertheless. In the main cargo compartment. In the event of smoke detection. The heating function is deactivated in this operation. trim air valve. optional): Ventilation system is based on air suction provided by an extraction fan or by a venturi tube in flight when the pressure difference is sufficient.A. The air enters the compartment through one side wall and ceiling and is extracted on the other side. In the case of temperature regulation. the air enters pressurized and conditioned. the basic fan heaters can be controlled by an ON/OFF switch on the aft compartment servicing panel in order to activate the blowing function when the aircraft is on ground and the cargo compartment door is fully open. There are means to exclude hazardous quantities of smoke. Fire protection: We consider two airworthiness requirements: − Class “C” (FAR 25.There is an approved built-in fire-extinguishing system controllable from the pilot or flight engineer station 3. flames or other noxious gases from any compartment occupied by the crew or passengers 4. CARGO SYSTEMS SYSTEMS 2.There is a separate approved smoke detector or fire detector system to give warning at the pilot or flight engineer station 2.4.There are means to control ventilation and drafts within the compartment so that the extinguishing agent used can control any fire that may start within the compartment. which has a smoke detection and an automatic fire extinguishing system and burn through resistant lining. it is a compartment.857(c)): A class “C” cargo or baggage compartment is one in which: 1. 34 Getting to Grips with Aircraft Weight and Balance .6.{Reserved} To sum up.A. 5. they change the voltage of an ionization chamber. An electronic circuit inside the detector estimates this change. When the bottle content is discharged. CARGO SYSTEMS • The fire protection system consists of two sub-systems: a) A dual loop smoke detection system: Ionization-type smoke detectors are installed in cavities in the ceiling of each compartment. one without flowmeter and the second with flowmeter.(see picture above). With a detector failure. a pressure switch activates lamps in the cockpit to confirm that the agent has been discharged. Each cavity contains two detectors. The extinguishing agent (Halon 1301) is discharged to either the forward or aft lower deck holds. signaling from two detectors is required to produce a smoke warning. Note: Smoke detectors: When combustion gazes enter the detector.A. Detectors are controlled and operated by the Smoke Detection Control Unit (SDCU) as a dual loop system using and/or logic principle requiring that. Discharge cartridges without flowmeter Discharge cartridges with flowmeter Getting to Grips with Aircraft Weight and Balance 35 SYSTEMS . amplifies it and transmits the information to the flight deck) Smoke detectors and Extinguishing nozzle b) A Fire extinguishing system: This system consists of two fire suppression bottles (just one bottle for the A320 family) which are installed behind the sidewall lining. The discharged cartridges are electrically ignited by guarded switches located on the overhead panel. in each compartment. the system reverts to a single-loop operating condition. which the sampled air passes through. . FUEL SYSTEMS FUEL SYSTEMS INTRODUCTION This part describes general aspects of the aircraft fuel systems such as fuel capacities. fuel control computers as well as the impact on CG position (CG movement during refueling and CG movement in flight). Fuel computers on board the aircraft manage the fuel sequence. the most obvious being the location of the fuel tanks. the refueling and defueling sequences follow the same guidelines. Getting to Grips with Aircraft Weight and Balance 37 SYSTEMS . Due to some structural issues common to all aircraft. in the fuselage (center tank and additional center tanks – ACT) and in a trim tank located in the THS (except for A320 family and some A300/A310 aircraft).B. These tanks are located in the wings. All Airbus aircraft fuel systems described in this part have some common characteristics. fuel has to be kept in the wing as long as possible. Bending moments Lift 2 Lift 2 Weight = mg Important structural strain On the one hand. this weight is balanced by the lift created mainly on the wings. FUEL SYSTEMS SYSTEMS B. GENERALITIES The main part of the aircraft weight and most particularly the payload is located in the fuselage. FUEL SYSTEMS 1. In flight.B. This distribution generates a bending moment around the wing root. Bending moments Lift 2 Lift 2 mfuelg mfuselageg mfuelg 38 Getting to Grips with Aircraft Weight and Balance . the weight of the fuel tanked in the wings balances the effect of the lift and thus reduces the bending moment. the fuel in the fuselage is an extra load the wings have to create lift for. So. This has a strong impact on the aircraft structure and leads to define a Maximum Zero Fuel Weight (MZFW) in order to limit the stress at these locations. On the other hand. FUEL SYSTEMS This is the reason why the wing tanks are the first tanks to be filled and the last ones to be emptied and this no matter the aircraft type. Moreover. On top of this general considerations. However. A330/A340 and A300-600/A310) has its own characteristics. the outer tank is filled first in order to bring the m fuel g vector further out. as the wing tanks are generally divided into outer and inner wing tanks (except on A321). in-flight fuel transfers CG control system (when applicable) Getting to Grips with Aircraft Weight and Balance 39 SYSTEMS . A318/A319/A320/A321.B. That is why this part presents the following aspects for each aircraft family separately: − − − − − Fuel tanks: location and capacities Fuel systems: engine feed system. control and indication CG travel during refueling: refueling sequence and resulting fuel vector In-flight CG travel: defueling sequence. it is worth pointing out that this rule is only applicable to a certain extent : too much weight in the outer tanks creates some structural strain on the wings on ground (ie when not balanced by the lift). each aircraft family (ie. B. Please refer to Weight and Balance Manual for relevant information. THE SINGLE-AISLE FAMILY (A318/A319/A320/A321) 2. 40 Getting to Grips with Aircraft Weight and Balance . Tanks and capacities Compared with A318/A319/A320. FUEL SYSTEMS SYSTEMS 2. contrary to all the other Airbus aircraft. which has no center tank and slightly dissymmetrical inner tanks.1.1. Optional additional center tanks for A319/A320 200/A321 Wing tank A321 A318/A319/A320 2. there is no separation between outer and inner tanks on A321. A321 wings have been modified in order to support higher weights. A318/A319/A320 Note : One or two optional additional center tanks can be fitted (on the A319 and A320-200 only) Fuel Capacity (Usable fuel) – density: 0.1. As a consequence.785kg/L Total Total Total Outer Inner Center without with 1 with 2 Tanks Tanks ACT Tank ACT ACT ACTs (x 2) (x 2) 23860 26852 29844 Liters 880 6925 8250 2992 Volume 6304 7094 7885 US Gal 232 1830 2180 790 18730 21079 23428 Kg 691 5436 6476 2349 Weight 41292 46471 51649 Lb 1523 11984 14277 5179 Note: this does not apply to the A320-100. 4. 2. A319 Corporate Jet The A319 CJ can be fitted with up to six additional center tanks.785kg/L Outer Tanks Volume Liters US Gal Kg Weight Lb 880 (x2) 232 (x2) 691 (x2) 1523 (x2) ACT 1 Volume Liters US Gal Kg Weight Lb 3104 820 2437 5372 ACT 2 2180 576 1711 3773 Inner Tanks 6925 (x2) 1830 (x2) 5436 (x2) 11984 (x2) ACT 3 2180 576 1711 3773 ACT 4 3036 802 2383 5254 Center Tank 8250 2180 6476 14277 ACT 5 3104 820 2437 5372 Total without ACT 23860 6304 18730 41292 ACT 6 3104 820 2437 5372 Total with 6 ACTs 40568 10718 31846 70207 Note: Two fuel operating sequences are available on A319 CJ. 3.1. Due to specific issues raised by this configuration. 4. 3 and 5 and defueled in the reverse order.2. Fuel Capacity (Usable fuel) – density: 0. 6. Getting to Grips with Aircraft Weight and Balance 41 SYSTEMS . 2. 5 and 6 • Seq B: 1. applicable information will be presented separately from other A319 aircraft. ACTs are fueled in the following order : • Seq A: 1. Please refer to the Weight and Balance Manual for applicable information.B. FUEL SYSTEMS 2. 3.1.785kg/L Total Wing Center without Tanks Tank ACT 23700 Liters 7745 8210 Volume 6261 US Gal 2046 2169 18605 Kg 6080 6445 Weight 41015 Lb 13404 14208 ACT 2992 790 2349 5178 Total with 1 ACT 26692 7052 20954 46193 Total with 2 ACTs 29684 7842 23302 51371 42 Getting to Grips with Aircraft Weight and Balance . A321 Note : One or two optional additional center tanks can be fitted (on A321-200 only) Fuel Capacity (Usable fuel) – density: 0. FUEL SYSTEMS SYSTEMS 2.B. FUEL SYSTEMS 2. Fuel transfers from center tank to wing tanks are managed through a transfer valve. So.B. Control and indication The A320 family aircraft are fitted with a Fuel Quantity Indication (FQI) system and three Fuel Level Sensor Control Units (FLSCU). fuel transfer is made by pressurization. there are six main pumps: two pumps in the center tank (except A320-100 which has no center tank) and two pumps in each inner tank. A319 and A320 aircraft. As explained above. − One CIC (capacitance Index Compensator giving the dielectric constant of the fuel) to give the density in case of cadensicon failure. Engine feed and fuel transfer On A318. the fuel system only deals with fuel quantities and tank transfer issues. valves between outer and inner open and an automatic gravity transfer occurs. 2.2. each engine is supplied from two pumps in its own side wing tank. When inner tanks reach low level.2. ACTs) 2. Fuel System The standard body family has the simplest fuel systems. Indeed. The FQI provides the crew with information regarding fuel (total fuel mass.2. the benefits of a CG control system on the much shorter missions of the A320 family aircraft would be negligible compared with the cost related to the installation of a CG control system (maintenance costs and extra weight on board). some differences can be observed depending on the aircraft type and on the modifications fitted on the aircraft (e. On A321. A318/319/320 ECAM fuel page Getting to Grips with Aircraft Weight and Balance A321 ECAM fuel page 43 SYSTEMS .g. − One densitometer (cadensicon) sensor in each wing inner tank (in wing tank for A321) to measure density of fuel and. ACTs are emptied one by one into the center tank. When aircraft are equipped with ACTs (Additional Center Tanks).2. Each engine is fed with one pump in the center tank and with the two pumps in its own side inner tank. as it is neither equipped with a CG control system nor a trim tank.1. quantity and temperature in each tank) via the ECAM and based on data from: − A set of capacitance probes in each tank measuring fuel level and temperature. The following diagram presents the fuel system architecture: WING TANK PROBES & SENSORS FLSCU (FUEL LEVEL SENSOR CONTROL UNIT) REFUEL VALVES REFUEL CONTROL PANEL ECAM UPPER DISPLAY FQI COMPUTER ECAM FUEL DISPLAY FLIGHT CREW ADIRS FMGS WING TANK PROBES & SENSORS 44 Getting to Grips with Aircraft Weight and Balance . The FLSCUs include probes and temperature sensors located in the tanks during refueling and transfer to detect low and high fuel levels in tanks. On A319CJ. specific units (AFMC .Auxiliary Fuel Management Computer and ALSCU . which can be fitted with up to 6 ACTs. They generate signals that are used to operate the valves during refueling and transfers (from center tank to wing tanks as well as from ACTs to center tank). FUEL SYSTEMS SYSTEMS The FQI also controls the automatic refueling by determining the target levels in each tank.B.Auxiliary Level Sensor Control Unit) are dedicated to ACT fuel management. CG travel during refueling 2. Inner tanks (full) Center tank (full) ACT1 then ACT 2 (if applicable) 3 4 5 3 6000 1 -15 2000 0 5 2 -5 Delta Index The graphs below illustrate examples of the fuel vector impact on the certified CG envelopes: 80 75 70 Weight (tonnes) 80 75 70 Weight (tonnes) 65 60 55 50 45 40 35 10 30 50 Index 70 90 110 65 60 55 50 45 40 35 10 30 50 Index 70 90 110 A318 A319 (no ACT) Getting to Grips with Aircraft Weight and Balance 45 SYSTEMS . valves between the outer and inner tanks open and fuel spills from the outer to the inner tanks (2).1. A318/A319/A320 The refueling sequence and the resulting fuel vector are the same for A318. FUEL SYSTEMS 2.3. If an inner tank contains less than 750 kg of fuel.B. A319 and A320 aircraft: 24000 22000 20000 18000 Fuel Weight (kg) 5 1 4 16000 14000 12000 10000 8000 4000 Outer tanks (full).3. 46 Getting to Grips with Aircraft Weight and Balance . due to the range of the fuel vector.B. FUEL SYSTEMS SYSTEMS 80 75 70 Weight (tonnes) Weight (tonnes) 80 75 70 65 60 55 50 45 40 35 10 30 50 Index 70 90 110 65 60 55 50 45 40 35 10 30 50 Index 70 90 110 A319 CJ (with 6 ACTs – Seq B) A320 (with 2 ACTs) Note: On A319CJ. specific ZF envelopes have been certified in order to ensure that CG is kept inside the limits in case of failure of the fuel transfer function from the ACTs to the center tanks. 2. FUEL SYSTEMS 2. 95 90 85 Weight (tonnes) 80 75 70 65 60 55 50 45 0 10 20 30 40 50 60 Index 70 80 90 100 110 Getting to Grips with Aircraft Weight and Balance 47 SYSTEMS .B. A321 The refueling sequence for the A321 and the resulting fuel vector are the following: 24000 22000 20000 18000 Fuel Weight (kg) 16000 3 1 2 3 Wing tanks (full) Center tank (full) ACTs (if applicable) 2 14000 12000 10000 8000 6000 4000 1 2000 0 -5 0 5 Delta Index 10 15 -15 -10 The following chart presents the impact of the refueling vector on the certified CG envelopes.3. A319. In-flight CG travel 2. This transfer brings the CG forward. the fuel vector is the same for refueling and defueling. A321 On A321.4. The valves between the outer tanks and the inner tanks open and are latched open until the next refueling.B. FUEL SYSTEMS SYSTEMS 2.1. The fuel burn sequence is therefore the following: 1/ ACTs (ACT2 then ACT1) – fuel transferred to the center tank (if applicable) 2/ center tank – fuel transferred to the wing tanks 3/ wing tanks So. All the fuel located in the center and auxiliary tanks have to be pumped into the wing tanks in order to be burnt. 2. A318/A319/A320 The fuel burn sequence for the A318. 48 Getting to Grips with Aircraft Weight and Balance .2.4. the fuel vector for defueling is the same as for the refueling.4. only the wing tanks are fitted with engine feed pumps. As a consequence. This does not necessarily occur simultaneously in both wings. A320 is as follows: 1/ ACTs (ACT2 then ACT1) – fuel transferred into the center tank (if applicable) 2/ center tank (until empty) 3/ inner tanks (until 750kg left in each tank) 4/ outer tanks – all the fuel transferred to the inner tanks from where it is fed to the engines 5/ inner tanks (until empty) The only transfer that takes place is the transfer of fuel from the outer to the inner tanks when the fuel quantity in the inner tanks reaches a low level of 750kg. THE LONG-RANGE FAMILY (A330/A340) 3.1.B. Getting to Grips with Aircraft Weight and Balance 49 SYSTEMS . please refer to the Weight and Balance Manual or to the Aircraft Flight Manual.1. For relevant information. Fuel Capacity (Usable fuel) – density: 0.1. A330-200/-300 As far as fuel is concerned. the main difference between the models is that the A330-200 is fitted with a center tank in order to cover longer-range missions than the A330-300 A330-200 only The following table gives the detail of fuel tanks capacity on the A330. FUEL SYSTEMS 3.785kg/L Outer Inner Tanks Tanks Trim Tank (x2) (x2) Liters 3650 42000 6230 Volume US Gal 964 11096 1646 Kg 2865 32970 4890 Weight Lb 6316 72686 10780 Total A330-300 97530 25767 76560 168784 Center Tank 41560 10980 32625 71925 Total A330-200 139090 36748 109185 240709 Note: These values are applicable to for all A330-200 and for A330-300 from MSN 256 and above. Tanks and capacities 3. B. Fuel Capacity (Usable fuel) – density: 0. 50 Getting to Grips with Aircraft Weight and Balance .785kg/L Outer Inner Tanks (x2) Tanks (x2) Liters 3650 42775 Volume US Gal 964 11301 Kg 2865 33578 Weight Lb 6316 74026 ACT Volume Weight Liters US Gal Kg Lb 7200 1902 5652 12460 Total with ACT 148700 39287 116728 257339 Center Tank 42420 11207 33300 73413 Trim Tank 6230 1646 4890 10780 Total 141500 37384 111076 244878 Note: These values apply for all aircraft from MSN 179 and above and to some previous MSNs. A340-200/-300 Note: One optional additional center tank can be fitted.1.2. please refer to the Weight and Balance Manual or to the Aircraft Flight Manual. FUEL SYSTEMS SYSTEMS 3. For relevant information. The information presented in this brochure is applicable to 5-frame RCT. A340-500/-600 inner tanks have been split into two inner tanks per wing. FUEL SYSTEMS 3. Getting to Grips with Aircraft Weight and Balance 51 SYSTEMS .3.B. A340-500/-600 Compared with A340-200/-300. Please refer to Weight and Balance Manual or to the Aircraft Flight Manual for relevant information.785kg/L Inner Inner Outer Center Tanks Tanks Tanks 1&4 2&3 Tank (x2) (each) (each) Liters 6310 24716 34805 55133 Volume US Gal 1667 6530 9195 14566 Weight Kg Lb 4953 10920 19402 42774 27322 60234 43279 95413 Trim Tank 7986 2110 6269 13821 Total A340600 194781 51461 152903 337088 Rear Center Tank 19873 5250 15600 34392 Total A340500 214654 56712 168503 371480 Note: Some aircraft modifications may affect the tanks capacity on A340-500/-600. two RCT sizes are available on A340-500 (5 or 7 frame). Particularly. mainly for engine burst considerations. Moreover.1. an extra tank (rear center tank) has been installed on A340-500 A340-500 only Fuel Capacity (Usable fuel) – density: 0. Each cell includes two main fuel pumps. When the cross feed valves are open. The collector cells located in the inner tanks ensure the engine feed. The CG control system generates trim tank transfers during the flight: − Forward transfers: Some aircraft are equipped with one trim tank forward transfer pump for the fuel transfers from trim tank to the inner tanks or to the center tank. One standby pump is installed in the inner tank outside the collector cell. In order to take advantage of the large amount of fuel on board and of the possible influence that this fuel position may have on the aircraft CG position. − Aft transfers: Fuel is provided from the center tank through the two center tank pumps mentioned above The fuel from inner tank is transferred using the two engine feed pumps On A340-500/-600 aircraft. For all A340s. Each collector cell contains about 1000 kg and is maintained full in order to protect the engine feed. FUEL SYSTEMS SYSTEMS 3.2. Fuel transfers This paragraph aims at briefly describing how the various fuel transfers are performed during the flight. each collector cell consists in one main fuel pump and one standby fuel pump. In case of the pump failure or if the aircraft is not fitted with it. two collectors cells are located in each inner tank.2. 3. A330/A340 aircraft are fitted with a CG control system involving trim tank transfers that enables to keep the CG as aft as possible during the flight to optimize the fuel consumption. there is one collector cell in each of the four inner tanks. these transfers are done by gravity. A340-500/-600 aircraft are basically fitted with two forward transfer pumps. transfers to trim tank are performed via six dedicated aft transfer pumps (two in the center tank and one per inner tank). any pump is able to supply any engine. That implies that the fuel from the other tanks has to be transferred in the inner tanks: − Two pumps enable the transfer from center tank (when applicable).2. − Fuel transfer from outer tanks is done by gravity and controlled by transfer valves. The main differences between the models mainly result from the number of engines and from the tanks that actually equip the aircraft. On A340500/-600. For ACT (when fitted) and for RCT on A340-500. there is one collector cell per inner tank. − On A340-200/-300. 52 Getting to Grips with Aircraft Weight and Balance . the fuel is transferred to the center tank by pressurization. Fuel systems All the aircraft of the long-range family basically follow the same guidelines in terms of fuel system. 3. Engine feed A dedicated collector cell located in the inner wing tanks feeds each engine: − On A330.1.B. They run continuously as long as there is fuel in the center tank. A cross feed valve is associated with each engine.2. electrical characteristics and temperature) is provided to the FCMCs via two Fuel Data Concentrators (FDC). Their main functions are: − Fuel transfer control − Aircraft gross weight and CG position calculation − Center of gravity control − Refuel control − Fuel quantity measurement and indication on ECAM and on refuel control panel. Control and indication On long range family aircraft. Getting to Grips with Aircraft Weight and Balance 53 SYSTEMS .3. FUEL SYSTEMS 3. Fuel level sensors also provide the FCMC with information used to control transfers and to trigger warnings independently of the fuel quantity indication.2. A340-200/-300 ECAM fuel page A340-500 ECAM fuel page In normal operation. the fuel system (FCMS : Fuel Control and Monitoring System) is controlled by two Fuel Control and Monitoring Computers (FCMCs). density. the tank data (volume. Fuel quantity calculation performed by FCMC is based on the following information: − Fuel volume from tank probes − Fuel density from densitometers − Horizontal stabilizer angle − Aircraft attitude − Fuel electrical characteristics from compensators On A340-500/-600.B. one FCMC is active while the other is in stand-by. ZFW. FUEL SYSTEMS SYSTEMS The following diagram presents the fuel system architecture: BLOCK FUEL. sensors. indication and control and control ! Level sensing ! Level sensing ! Temperature indication ! Temperature indication ! Warnings ! Warnings ! Stop jettison operation ! Stop jettison operation Refuel Refuel panel panel Fuel system Fuel system ! Valves ! Valves Fuel system isolation Slats extended Gross weight/CG Maintenance data (bite) SFCC SFCC SFCC SFCC WBC WBC Option 2 1 ! Pumps ! Pumps ! Pressure switches ! Pressure switches ! ! ! ! Temperature sensors Temperature sensors Level sensors Level sensors (thermistors) (thermistors) CMC CMC CMC CMC ! Fuel quantity ! Fuel quantity sensors. densitometers and densitometers and compensator compensator 54 Getting to Grips with Aircraft Weight and Balance . ZFWCG ACARS ECAM ECAM FMGEC FMGEC AFT CG warning FWC FWC FWC FWC Gross weight AFT CG target/caution ZFW and ZFWCG FCMC FCMC FCMC FCMC Functions Functions ECAM ECAM Cockpit Cockpit overhead overhead panel panel ACMS ACMS DMU DMU MCDU TTD ADIRS ADIRS ADIRS ADIRS ADIRS ADIRS FADEC FADEC FCMC INTERFACE WITH AIRCRAFT SYSTEMS APU APU FCDC FCDC FCDC FCDC LGCIU LGCIU LGCIU LGCIU A/C attitude Recirculation THS position LDG gear up/down flight/ground ! Quantity indication ! Quantity indication ! ! ! ! Refuel control Refuel control Transfer/cross feed control Transfer/cross feed control ! Center of Gravity ! Center of Gravity Calculations. indication Calculations.B. which is the production standard at the date of the publication. all the tanks are filled simultaneously according to a given fuel distribution. The following information is based on FCMS 9. The following graph is published in FCOM 2.0 (10.30 and enables to determine the fuel distribution in each tank at the end of refueling as a function of the total fuel quantity: Refueling distribution A340-300 FCMS 7. and on the fuel tank capacities mentioned above.0).1.3. once a fuel quantity has been selected.01. A330-200-300 and A340-200/-300 The refueling sequence for A330 and A340-200/-300 is as follows: 120000 110000 100000 90000 Fuel Weight (kg) 80000 70000 60000 50000 40000 30000 20000 10000 -20 -15 -10 -5 0 7 6 8 5 4 2 0 5 10 15 20 25 30 35 40 45 Delta Index 1 inner tanks up to 4500 kg per side (to fill in the collector cells) 2 outer tanks (full) inner tanks up to total fuel equals 36500 kg 4 trim tank up to 2400 kg A330-200. A340: simultaneously trim tank (full) and center tank (full) 7 A340: ACT (if applicable) 3 5 6 8 inner tank (full) 3 1 A330-300: trim tank (full) Getting to Grips with Aircraft Weight and Balance 55 SYSTEMS . Please refer to the Weight and Balance Manual for applicable information. FUEL SYSTEMS 3.0 FCMS modifications have been introduced in order to optimize the fuel sequences by reducing the fuel vector range.B.3. 3. CG travel during refueling During automatic refueling. B. FUEL SYSTEMS SYSTEMS The graphs below illustrates the fuel vector impact on the certified CG envelopes: 240 220 200 Weight (tonnes) 180 160 140 120 100 50 70 90 110 130 Index 150 170 190 240 220 200 Weight (tonnes) 180 160 140 120 100 20 40 60 80 100 120 140 160 180 200 Index A330-200 280 260 Weight (tonnes) 240 220 200 180 160 140 120 40 60 80 100 120 Index 140 160 180 A330-300 200 A340-200/-300 (1 ACT) 56 Getting to Grips with Aircraft Weight and Balance . center tank (full). Total fuel = 157656 kg Inner tanks 1. Total fuel = 12000 kg (to fill in the collector cells) 2 Outer tanks up to up to 4500 kg per tank. 3 and 4 up to up to 18200 kg per tank. center tank up to 17000 kg and trim tank up to 2400 kg. Total fuel = 21000 kg 3 4 5 6 7 Inner tanks 1. Total fuel = 116200 kg Center tank up to 40000 kg and trim tank up to 5900 kg. trim tank (full) and for A340-500: rear center tank (full) This sequence leads to the following refueling vectors: 160000 140000 6 7 160000 140000 120000 Fuel Weight (kg) 100000 7 5 5 120000 Fuel Weight (kg) 100000 4 4 80000 60000 40000 20000 80000 60000 40000 3 2 0 5 10 15 20 3 2 0 5 10 20000 10 -10 -5 Delta Index 10 -5 Delta Index A340-500 A340-600 Getting to Grips with Aircraft Weight and Balance 57 SYSTEMS .2.2. A340-500/-600 A340-500 and A340-600 have similar refueling sequences: 1 Inner tanks 1. 3 and 4 (full). FUEL SYSTEMS 3. Total fuel = 142700 kg A340-500: rear center tank up to 14956 kg.3. 2.3 and 4 up to up to 3000 kg per tank. Total fuel = 81800 kg Inner tanks 2 and 3 up to 25700 kg per tank. outer tanks (full).B. 2. 360 Weight (tonnes) 310 260 210 160 40 60 80 100 120 Index 140 160 180 200 A340-500 360 Weight (tonnes) 310 260 210 160 20 40 60 80 100 120 Index 140 160 180 200 A340-600 58 Getting to Grips with Aircraft Weight and Balance . FUEL SYSTEMS SYSTEMS The following graphs give an example of the fuel vector impact on the certified CG envelope.B. cycling the inner tanks quantities between 17200 and 18200 kg. to maintain full quantity.4. which is detailed in the next paragraph. Getting to Grips with Aircraft Weight and Balance 59 SYSTEMS . Fuel burn CG travel This paragraph deals with in-flight CG travel due to depletion with no consideration of CG control. As described previously. until all inner tanks are balanced (approximately 18000 kg per inner tank) 3/ Rear center tank (if applicable) fuel transferred to the center tank when the center tank quantity reaches 1000 kg 4/ Center tank fuel transferred to all inner tanks. all the fuel from the other tanks have to be transferred to the inner in order to be burnt. which is not strictly followed in flight as the CG position is modified by the CG control system. engines are only fed from the inner tanks and so. until the center tank is empty 5/ Inner tanks down to 4000 kg per inner 6/ Trim tank fuel transferred to the inner tanks 7/ Inner tanks is emptied down to 2000 kg per inner 8/ Outer tanks fuel transferred in the inner tanks 9/ Inner tanks (until empty) All the transfers mentioned here are managed automatically by the fuel system. In-flight CG travel 3.4.1. the following depletion sequence is applicable to FCMS 9. FUEL SYSTEMS 3.0 standard : a) A330-200/-300 and A340-200/-300 − − − − − − − 1/ ACT (if applicable) fuel transferred to the center tank 2/ Center tank (if applicable) fuel transferred to the inner tanks 3/ Inner tanks down to a given level (ie 4000 or 5000 kg in each inner tank depending on the aircraft) 4/ Trim tank fuel transferred to the inner tanks 5/ Inner tanks is emptied down to a second given level (ie 3500 or 4000 kg in each inner tank) 6/ Outer tanks fuel transferred in the inner tanks 7/ Inner tanks (until empty) b) A340-500/A340-600 − − − − − − − − − 1/ Center tank fuel transferred to all inner tanks until center tank fuel quantity reaches 17000 kg 2/ Center tank fuel transferred to inner tanks 1 and 4. Besides. The fuel burn sequence is a reference vector.B. the fuel burn sequence for long-range family aircraft and the associated fuel transfers are in accordance with the basic structural constraints (wing root stress). As for refueling data. The graph below is published in FCOM 1. which depends on the aircraft weight.5%.28. FUEL SYSTEMS SYSTEMS 3. According to this calculated CG position compared to the target. It calculates the CG position and compares it to a target value.4.A340-300 The FCMC determines the fuel quantities to be transferred to maintain the aircraft CG in a control band limited by the CG target position and CG target position – 0.10 and provides with the target CG expressed in %MAC as a function of the aircraft weight: AFT CG Target . Considering a typical CG envelope layout.B.2. an aft CG position reduces the drag and then implies fuel savings. CG control system The position of the aircraft CG during the flight has an impact on the fuel consumption. a) CG target In flight. the FCMC determines the fuel quantity that needs to be transferred aft or forward. That is the reason why a CG control system has been introduced on long-range family aircraft. Indeed. the control band can be presented as follows: Aircraft Weight CG control band MTOW Certified CG envelope ZFW 60 Getting to Grips with Aircraft Weight and Balance . the FCMC controls the position of the center of gravity. B. it can happen that an additional aft transfer occurs when both the CG position is 2% forward the target value and the trim tank reaches a low level. FUEL SYSTEMS b) CG control The following profile describes the CG control system behavior throughout the flight: The CG control function is active once the aircraft has reached FL 255. However. CG control starts with an aft transfer to the trim tank when all the following conditions are met: − The landing gear is up and the slats are retracted − The trim tank is not full − The aircraft CG is not on the target − Each inner tank quantity is above 6250kg (6000 kg for A340-500/-600) − The Flight Level is above FL 255 Normally only one aft transfer is generated during the flight. − Jettison is selected Getting to Grips with Aircraft Weight and Balance 61 SYSTEMS . which depends on the aircraft type and on whether a trim tank pump is fitted and operative.0. It is deactivated when the aircraft flies below FL 245 or when time-to-destination from the FMGS is less than a given value. An aft transfer ends if one of these conditions is fulfilled: − The computed CG reaches Target CG .5% − The trim tank is full − The inner tank quantity reaches 6250kg (4000 kg for A340-500/-600) − The crew requests a manual fuel transfer (forward trim transfer or transfer from the center or outer tanks to the inner tanks). center tank and inner tanks depletion brings the CG further aft. these positions are linked to the ZFW and ZFCG values input by the pilot before flight in the MCDU. an aft CG warning is triggered that requires a manual forward transfer.5% or 2%). either forward transfer is directed to the lightest tank or aft transfer is stopped on the lightest tank. c) CG target possible shifts during flight During the flight all the fuel transfers are based on the CG position determined by the FCMC. In this case. Automatic forward transfers from the trim tank (and also from the RCT on A340-500) keep the CG position within the CG control band. 62 Getting to Grips with Aircraft Weight and Balance . If the CG position computed by the FMGC is too far aft. the target also moves forward by 1. FUEL SYSTEMS SYSTEMS Then. An independent CG determination is made by the FMGC. In case the inners are unbalanced by more than 500 kg.B. The transfer stops when the level reaches 5000 kg (or respectively 6000 kg). If the resulting corrections are not enough to avoid the CG position to excess the FE limit. during the normal fuel burn. the target CG position in the FCMC is automatically shifted forward (by 1. − The FMGS sends a time-to-destination signal or the aircraft is in descent below FL245. These transfers occur in each of the following circumstances: − The Calculated CG position reaches the target CG. These transfers take into account potential tank imbalance that can be encountered during the flight.5% in case of FQI data degradation or if ZFCG/ZFW have not been entered or need to be reinitialized. the fuel transfer is continuous and stops only if the inner tanks are overflowing.5% − The fuel quantity in one of the inner tanks decreases down to 4000 kg (or 5000 kg depending on the aircraft). In order to protect the aft CG limitation. The transfer stops when the calculated CG reaches CG Target -0. 3 t Trim fwd transfer Trim fwd transfer MTOW MTOW CG control A340 wings half full ~ 60 t Trim aft transfer Trim aft transfer Inner depletion Trim fwd transfer Trim fwd transfer Getting to Grips with Aircraft Weight and Balance 63 SYSTEMS . FUEL SYSTEMS d) Example of CG control operation Automatic fuel transfers that actually happen during the flight depend on the initial amount of fuel in the tanks and on the aircraft Zero Fuel CG position.B. The following table presents the different cases that can be encountered according to the initial conditions (CG position and fuel quantity): Refuel vector (Metric tonnes) Control band reached MTOW ACT Trim and center Depletion vector CG control band Control band not reached MTOW A340-300 max full ~ 116.7 t Inner wings Outer wings Collectors Center depletion Trim Center + ACT depletion CG control Inner depletion Inner depletion Trim fwd transfer Trim fwd transfer MTOW Trim aft transfer MTOW Trim aft transfer Inner depletion CG control A340-300 wings full ~ 75. 785kg/L A310-200 A310-300 Volume Liters US Gal Kg Weight Lb Outer Tanks (x2) 3700 978 2905 6403 Inner Tanks (x2) 13950 3686 10951 24143 Center Tank 19640 5189 15417 33988 Total A310 -200 54940 14515 43128 95080 Total A310 Trim ACT Tank -300 1 ACT 6150 61090 7200 68290 1625 16140 1902 18042 4828 47956 5652 53602 10644 105724 12460 118184 Total A310 -300 Total A310 -300 2 ACTs 75490 19944 59260 130644 64 Getting to Grips with Aircraft Weight and Balance . FUEL SYSTEMS SYSTEMS 4. Please refer to the Weight and Balance Manual for applicable information.782kg/L Total Outer Inner A300-600 Center A300Tanks Tanks A300-600R Tank 600 (x2) (x2) Volume Liters US Gal Kg Weight Lb 4630 1223 3621 7982 17570 4642 13740 30290 Total A300 ACT -600 1 ACT 17600 62000 6150 68150 7000 69000 4650 16380 1625 18005 1849 18230 13763 48483 4809 53292 5474 53957 30342 106886 10602 117488 12068 118954 Trim Tank Total A300 -600R Total A300 -600 2 ACTs 76000 20079 59431 131022 Fuel Capacity (Usable fuel) – density: 0. Tanks and capacities Note : One or 2 ACTs can be installed on A300-600 and A310-300.B. THE WIDE-BODY FAMILY (A300-600/A310) 4. Fuel Capacity (Usable fuel) – density: 0.1. The pumps supply both engines simultaneously. The pumps in the outer tanks are kept on throughout the flight. Getting to Grips with Aircraft Weight and Balance 65 SYSTEMS . The CGCC (Center of Gravity Control Computer) controls the transfers from and to the trim tank. Engines are fed: − From the center tank when the aircraft is on ground and in flight when slats are retracted. The Autofeed system is activated when at least one pump pushbutton is switched in NORMAL position for each inner tank and for the center tank. outer and center tank) is equipped with two fuel pumps. the center of gravity control system is independent of the fuel feed and the refueling system. The tail trim tank (when applicable) is fitted with two transfer pumps for aft transfers generated by the CG control system. The outer tank pumps are not managed by the Autofeed system. the fuel is transferred in the center tank by pressurization. They run continuously during the flight. ACT fuel transfer pump is used on ground and in case of the pressurization system failure.B. When the aircraft is equipped with ACT(s). on the fuel quantity indicator on the overhead panel and on the external fuel panel. Control and indication The FQI (Fuel Quantity Indicating) computer provides the crew with fuel quantity information by processing data from: − A fuel specific gravity sensor (Cadensicon) − An attitude sensor which provides with aircraft pitch attitude and bank angle − A compensator probe in each tank for the fuel dielectric characteristics The resulting fuel quantity is displayed on the ECAM fuel page. 4. − From inner tanks at takeoff. FUEL SYSTEMS 4. with slats extended and when the center tank is empty. Fuel Systems 4. The FQI uses this information to monitor the refueling by closing the refuel valves when the preset quantities are reached. The Fuel Autofeed System controls the inner tanks and center tank pumps according to the normal fuel feed sequence.2.1. This transfer is inhibited during trim forward transfer to the center tank. Engine feed and fuel transfers Each of the five main fuel tanks (inner.2. Contrary to the long-range family. − From the outer tanks when the inner and center tanks are empty.2.2. CG Travel during refueling Tanks are refueled in the following order: 60000 50000 60000 5 3 Fuel Weight (kg) 50000 5 6 1 2 3 4 5 6 Outer tanks Inner tanks Center tank A300-600 and A310-300: ACT 1 (if applicable) A300-600R and A310-300 : Trim tank A300-600 and A310-300: ACT 2 (if applicable) 4 40000 Fuel Weight (kg) 40000 3 30000 20000 10000 0 30000 20000 2 2 1 10 20 30 40 50 60 Delta Index 10000 1 Delta Index 0 -20 -10 0 -20 -10 0 10 20 30 40 50 60 Refueling vector A300-600R Refueling vector A310-300 with 2ACTs The graphs below give an example of the fuel vector impact on the certified CG envelope: 170 160 150 Weight (tonnes) 140 130 120 110 100 90 0 10 20 30 40 50 60 Index 70 80 90 100 110 Weight (tonnes) 160 150 140 130 120 110 100 90 10 20 30 40 50 60 70 Index 80 90 100 110 120 A300-600 (no ACT) A310-300 (1 ACT) 66 Getting to Grips with Aircraft Weight and Balance .3. FUEL SYSTEMS SYSTEMS 4.B. CG control system Only A300-600R and A310-300 are equipped with a trim tank and an associated CG control system. As for long-range aircraft. the CGCC generates a forward fuel transfer from the trim tank to the center tank. the CG target is defined as a function of the aircraft weight. Once the inner tanks are empty. the Autofeed system controls the fuel feed sequence. The following graph is published in FCOM. Automatic fuel transfer from ACT to the center tank occurs when center tank high level has been dry for ten minutes. 4. The normal depletion vector is a reference that is not actually fulfilled as the CG position is impacted by the CG control system. the trim tank is isolated.B.4. Center of Gravity control and monitoring is achieved by the CGCC (Center of Gravity Control Computer). FUEL SYSTEMS 4. CG target A310-300 During takeoff and landing.5. It stops when the center tank high level is rewetted. the fuel quantity in each tank and the aircraft pitch angle. It also depends on the flight level. The trim tank isolation valve opens at takeoff when the slats are retracted and closes at landing when the gear is down. In-flight CG travel The normal fuel burn with no consideration of the CG control system is as follows: − 1/ ACT 2 then ACT 1 (when applicable) fuel transferred in the center tank − 2/ Center tank − 3/ Inner tanks − 4/ Trim tank fuel transferred progressively in the center tank until the trim tank is empty − 5/ Center tank − 6/ Outer tanks As explained previously. Getting to Grips with Aircraft Weight and Balance 67 SYSTEMS . The CGCC has three main functions: − To compute the aircraft CG and gross weight based on the ZFCG and ZFW (entered by the crew in the CDU). − To monitor the CG and maintain a CG target − To order fuel transfers in order to maintain the CG target. The CG target is also moved forward in case of a manual forward transfer (for more than 10 seconds) and when FQI data accuracy is degraded. As for the long-range family. the CGCC orders a fast forward fuel transfer from the trim tank to the center tank. the CGCC transfers fuel from trim tank into the center tank in order to maintain fuel quantity in the center tank (500 to 1000 kg). In case the CG is found too far aft. Above FL205. However. In order to protect the aft CG limit. In descent below FL 200. In climb below FL 205.5% forward of the CG target. FUEL SYSTEMS SYSTEMS CG control is activated above FL 205. forward transfers can be initiated if the aircraft reaches its aft CG target. an independent CG monitoring is performed by the FWC (Flight Warning Computer) based on THS position data. 68 Getting to Grips with Aircraft Weight and Balance . the CGCC initiates fuel transfers in order to maintain the CG within 0. This is done without any regards to the CG target. The fuel used in aft transfers comes from the center tank or from the inner tanks if the center tank is empty. This stops when one of the following conditions is met: − the trim tank is empty − the center tank is full − the CG has reached the forward CG limit. Forward transfers bring fuel from the trim tank to the center tank. no aft transfer is permitted. this starts with an aft fuel transfer (normally only one per flight) and continues with forward fuel transfers to compensate for the fuel burn. If the inner tanks are empty. No fuel can be transferred from the trim tank to the inner tanks.B. an ECAM warning is triggered and the CG target is shifted forward. With the LPCWBU interface. LPC WEIGHT AND BALANCE SYSTEM C. Weight & Balance. Various checks are performed throughout the data entry process and at the end. LESS PAPER IN THE COCKPIT WEIGHT AND BALANCE SYSTEM 1. load the aircraft with passengers. cargo and fuel and distribute the payload in the cabin and in the holds. The Less paper cockpit package is a more comprehensive package comprising of document consultation (FCOM and/or MEL) and of performance computation (Takeoff. pilots define the configuration of the flight. Each module may be present or not depending on the operator’s choice.C. The user interface of the Less Paper in the Cockpit – Weight & Balance module (termed as LPCWBU in the following) uses the data exclusively defined by the administrator. To complete these tasks. Landing. the LPCWB package is delivered as an empty shell and the administrator has to feed the LPCWB environment with the fleet’s weight and balance data (aircraft main characteristics. The interface runs on a laptop equipped with Windows operating system. GENERALITIES The Less Paper in the Cockpit – Weight & Balance module is an interface designed for the pilot for use in the cockpit to compute the different weights and center of gravity (CG) positions of the aircraft and to check them against their operational limitations. Getting to Grips with Aircraft Weight and Balance 69 SYSTEMS . The administrator defines also the general layout and operations of the user interface as this latter is very flexible and can be adapted to the airline's type of operations. pilot gets results graphically and numerically. Indeed. Flight). the administrator uses the dedicated functions of the administrator interface namely LPCA and in addition can optionally use comprehensive data files produced the LTS software. fuel tanks data…) as well as the operational data (influence of passengers and cargo loading on the CG .operational envelopes). USER INTERFACE – GENERAL PRESENTATION 2 1 3 6 4 7 5 The interface is composed of the following frames: Aircraft frame: Displays information regarding aircraft selection made on welcome page (given for information only). − 3 Configuration frame (Shortcut <F3>): Allows defining the aircraft configuration before loading payload and fuel. 70 Getting to Grips with Aircraft Weight and Balance .SYSTEMS 2. This frame fulfils all the tasks of a conventional load sheet. cargo and fuel distribution − 7 Results frame: Presentation of results (numerically and graphically). − 6 Payload distribution (Shortcut <F6>) and Fuel distribution (Shortcut <F7>): Enables to visualize or define passenger. − 5 Inop Item (Shortcut <F5>) This function is not available at this version. − 1 and 2 Departure frame (Shortcut <F2>): Allows selecting the departure airport. − 4 Loading frame (Shortcut <F4>): Enables to load the aircraft. ........................................6.............. 108 1.......... 108 1....................................7................................... Certification requirements .................... Weight and Balance Manual.......... Certified limits design process .......................... 79 3..... Generalities.......................2.................................... 75 2.......5............ 111 1.90: Examples ................................. 1............................................................. Impact on takeoff performance.................... 1..................................... Impact on the stall speed ......................... 114 1.......................... 115 1. 99 4................................................................................... 77 3.................. 98 4... 100 4............................. 104 B..... 88 4..............6............................... 76 3.......................................5..... 1........ 75 1........4..... 93 4................. 77 3......91 4..... Section 2 : Weight Report...................................................9.......................................................................20: FUEL.............................................50: INTERIOR ARRANGEMENT ...................... Take-off Limitations.3................ 89 4.......................................................3...............................................60: CARGO............................................................................................... 87 3......................................................................................................... Summary ............1............................................................ Forces applied on flying aircraft ................. Impact on in-flight performance .............................................. Mean Aerodynamic Chord (MAC) ........................................................WEIGHT AND BALANCE ENGINEERING A.................................................................................................................. Impact on landing performance...........................................8................................4.......................................................80: ACTIONS ON GROUND ...... Center of Gravity (CG) ..............................2.............8... Final Approach Limitations ....... 115 1................................... 84 3...................................... 1..............................................00: GENERAL..................................................................1............................................................ 90 4.....2...........................................40: PERSONNEL ....................................................................................... 114 1.....................................................3................... Conclusion ........................................... 88 3..................................7..................................................... 1....................................... Aircraft stability and maneuverability Limitations ....... 99 4. Influence of the CG position on performance........ 1... 1........................................................ SUMMARY : CG ENVELOPES ..................................................................................................... 1....5..................................................................................... Definitions.......................................................................... Landing Limitations .................. 109 1.......................... 117 2... 1.. 108 1......30: FLUIDS .................................... 117 1...............4............1............................. 75 1................2................................................. Limitation summary ............................... 118 Getting to Grips with Aircraft Weight and Balance 71 WEIGHT AND BALANCE ENGINEERING ....... Section 1 : Weight and balance control..........6.........10: LIMITATIONS....... 75 1.....1.................................................................................... Certified limits definition .......................................... ................................................... 125 2............ ∆Index for one item ........... 176 3..............1.................................... 130 3....... Inaccuracy due to CG computation method.. ∆Index for fuel loading.................... Calculation principle ............. 186 5...... Objectives..................................................... Takeoff.......5........... 186 5......... Moment and Index definitions .......... 186 5................................................................. Aircraft modifications:............................ 184 5.......................1............................................ 167 3.......................................................................... Moment.....6................................... Item movements during flight impacting the aircraft CG position ..... 121 1........... In-Flight operational limits determination............................................................................................ Generalities........... 121 1......................................................................WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C............................. 191 1...... 187 5....................................................... Margins determination method ........................................ 187 5...............................................................................5....... 138 3.1......................4.......... 125 2....3... 192 3.................................................................... 121 1......................................................... Load and Trim Sheet software ....................3................ 135 3.................. 126 2.................................................... Balance Chart Design.............................. 192 3...... 182 4...4........................................ 123 2........2........3...... PART B: GENERAL INFORMATION .............................................2........2....... 162 3............................................. 194 3....2.. Zero Fuel limit determination. 125 2................................................ 135 3.......................................................................................................2.................................................... 135 3........................................................................................................5........................................................................................ operational limits determination .............................................................................................................................................................4.... Operational limits diagram................................. ∆Index for cargo loading............................................... Index........... cargo............................................ 191 2.... 192 3........................................... PART C: AIRCRAFT DATA..................... 178 4.... ∆index scales or tables for loaded items ...........5..... fuel) ... 175 3..........................................................8.............................................. PART D: LOAD PLANNING DATA.......7................................................................................................................................................................. PART A: COMMUNICATION ADDRESSES.......9...................................................... 193 3......................................... Introduction........................................................................................................................................3.... Software description ...... Operational margins customization ................................................... Inaccuracy on initial data (DOW and DOCG) ............ Inaccuracy on items loading on board the aircraft (passengers............................................................................................ 189 D.............. 127 2..................................... Aircraft configurations: ............. Total operational margins determination ..................................................1............ The AHM560 ..........6............ Index variation calculation (∆Index) .................... Unit system: .................................................................................... ∆Index for additional crew member ......... Cabin layout: ................................. Balance Chart Drawing principle.............. 140 3........ 191 3.....................................1..4...... 195 72 Getting to Grips with Aircraft Weight and Balance ........1..................... ∆Index for passenger boarding............. ∆Index for additional weight on the upper deck .2................ Landing..................... 181 4....... 128 2........... the way to express it in relation to the Reference Chord (RC) and to detail the forces applied on the aircraft. GENERALITIES GENERALITIES INTRODUCTION The purpose of this section is to present the impact of the aircraft CG position on aircraft performance and the certified limits design process.A. First it is necessary to define precisely what is the Center of Gravity. Getting to Grips with Aircraft Weight and Balance 73 WEIGHT AND BALANCE ENGINEERING . . A.00.2. the formula would be: H −armCG = 31. the position of the center of gravity (CG) is usually expressed in terms of percentage of MAC. The safe limits for the CG are also expressed in terms of percentage of MAC (the symbol used is %MAC) The MAC is a reference line used in the design of the wing.3380 + . This point is the reference when it comes to measuring moments.Example of the A330-200 The important points to notice are: − the position and dimension of the MAC − the position of the point located at 25% of the MAC’s length. DEFINITIONS 1. Conversion from %MAC to H-arm H −armCG − H −armLeading Edge of MAC × 100 % MAC = Length of MAC H −armCG − 31. The position of the CG has to stay within certain limits to ensure aircraft maneuverability and stability and also the aircraft structure integrity. 75 Getting to Grips with Aircraft Weight and Balance WEIGHT AND BALANCE ENGINEERING .1.27 × MAC In the above case. GENERALITIES A. the formula would be: % MAC = . its position relative to the wing and the fuselage is accurately known. 1. GENERALITIES 1.06.3380 In the above case. .00. 100 In order to facilitate the operator’s work. 0. For example.072700 Length of MAC × %MAC H −armCG = H −arm Leading Edge of MAC + 100 7. Center of Gravity (CG) The Center of Gravity or CG is the point where the aircraft’s weight is applied.05 page2). The position and dimensions of this reference line are mentioned in the Weight and Balance Manual (WBM Chapter 1. conversion tables from H-arm to %RC and conversion tables from %RC to H-arm are available in the Weight and Balance Manual in chapter 1. Mean Aerodynamic Chord (MAC) All the limitations and the definitions related to weight and balance aspects use what is called the Mean Aerodynamic Chord (MAC) or the reference chord (RC). − The weight.WEIGHT AND BALANCE ENGINEERING A. The pitch up moment is due to important balance arm between the aircraft CG position and the THS where the additional force is applied. Pitch down moment Center of Gravity Lift THS Downward force Center of Pressure Weight Pitch up moment Counter moment Note : for aircraft stability reasons the CP is always located behind the CG. applied on the center of pressure (CP). Center of Gravity Lift Drag Weight Thrust Center of Pressure b) Influence of the THS (Trimmable Horizontal Stabilizer) As lift and weight are not applied on the same point. This additional force creates both lift degradation and important pitch-up moment that counters the pitch-down moment. applied on the aircraft CG. − The thrust. 76 Getting to Grips with Aircraft Weight and Balance . − The lift. GENERALITIES 2. a pitch-down moment is generated during the flight. due to the engines power. a downward force is created by the Trimmable Horizontal Stabilizer (THS) which has to be trimmed accordingly. FORCES APPLIED ON FLYING AIRCRAFT a) Diagram of forces Let us first consider main forces applied on the aircraft. − The drag. Pitch down moment Center of Gravity Lift Center of Pressure Weight In order to keep the airplane level. Getting to Grips with Aircraft Weight and Balance 77 WEIGHT AND BALANCE ENGINEERING . All influences are linked to the impact of the CG position on the stall speed. CG forward ⇒High pitch down moment ⇒Need for high THS counter moment ⇒lift = weight + THS counter force ⇒Stall speed is high CG aft ⇒Small pitch down moment ⇒Need for small THS counter moment ⇒lift = weight + THS counter force ⇒Stall speed is smaller than for forward CG CG CP THS CG CP THS The more forward the CG position.A. At that speed the upward force (mainly lift) is equal to the downward force (mainly weight + THS counter force) applied on the aircraft. 3. GENERALITIES 3. Impact on the stall speed The stall speed (Vs) is speed at which the aircraft will stall.1. INFLUENCE OF THE CG POSITION ON PERFORMANCE The impact of CG position on performance varies depending on the flight phase. The lift is directly related to the aircraft speed: the faster the aircraft flies the greater the lift. the greater the stall speed (Vs) value. 78 Getting to Grips with Aircraft Weight and Balance . A300-600 and A310). GENERALITIES • Example : A340 (High Gross Weight A340-313 with CFM65-5C4 engines) at take off CONF 1+F. Note : For conventional aircraft (A300. The difference can reach 1. the airworthiness authorities have reconsidered the definition of stall speed: the stall speed is based on a load factor equal to 1g. Gear up The following graph gives the stall speed value for different aircraft weights. It is called Vs1g. For Fly by Wire aircraft (A319. This gives a stall speed that is lower than the stall speed at 1g. and for two different CG positions (Most forward CG and CG at 26%MAC). All operating speeds are expressed as functions of this speed. A320.WEIGHT AND BALANCE ENGINEERING A.94 Vs1g. Stall Speed at Take Off (Conf 1+F. A321.94 represents the relationship between Vs1g and Vsmin : Vsmin = 0. Fly by Wire aircraft have a low-speed protection feature (alpha limit) that the flight crew cannot override. is based on a load factor inferior to 1g.5 kts. the reference stall speed. Vsmin. Gear UP) 145 140 135 130 125 120 115 110 105 150 170 190 210 Weight (tons) 230 250 270 CAS (kt) Forward CG 26%MAC This graph confirms the stall speed corresponding to a forward CG position is higher than the stall speed for a CG at 26%MAC. A330 and A340). Airworthiness authorities have agreed that a factor of 0. 3. the aircraft will need a longer runway if its CG is forward. OAT 15°C. the better the takeoff climb performances.2. the smaller the TOD (the greater the TOW). The further aft the CG. a forward CG position leads to a nose-heavy situation and a difficult rotation.A. the better the takeoff roll performances. a forward CG position leads to a nose-heavy situation and a difficult climb.1.3. At takeoff: V2 ≥ 1.8 ∆TOD = 76.13Vs1 g ) Now. AC OFF. Taking into account no other limitation (gear strength. Optimized takeoff distance or takeoff weight The aircraft operating speeds are referenced to the stalling speed.5 CG at 26%MAC 3164. Takeoff climb An aft CG position gives the aircraft a nose-up attitude that helps the aircraft climb.569% CG at 26%MAC 5. the V2 value directly impacts the takeoff distance (or the takeoff weight). VMU…).42% !This example shows that.689% !The aircraft climb is facilitated with an aft CG position. GENERALITIES 3. AC OFF. Impact on takeoff performance 3. AI OFF. for a given TOW. The further aft the CG. Takeoff roll An aft CG position gives the aircraft a nose-up attitude that helps the rotation.7 m = 2.2. • Influence on Climb Gradient A340 CONF 3. On the contrary.2Vs (1. 79 Getting to Grips with Aircraft Weight and Balance WEIGHT AND BALANCE ENGINEERING . Zp 0ft TOW = 250 000 kg 2nd segment gradient Forward CG 5. 3. • Influence on TOD A340 CONF 3. VMU…). Vs V2 TOD So for a given TOD: the lower the stall speed (Vs) value. the greater the takeoff weight (TOW).2. Taking into account no other limitation (gear strength.2. On the contrary. Zp 0ft TOW = 250 000 kg TOD (m) Forward CG 3241. The further aft the CG. AI OFF. OAT 15°C.2. All takeoff performances in the certified Airplane Flight Manual are given for both these CG positions. when determining the aircraft takeoff performance (TOW. 80 Getting to Grips with Aircraft Weight and Balance . OAT 15°C. So instead of calculating the difference in gradient for the same take-off weight. it is interesting to determine the maximum take off weight for a given climb performance. The A320 and the A340 usually have a DOW CG of around 30%MAC and their most forward certified CG limit is around 17%MAC.e. the allowed TOW is increased when the CG is aft. everyday operations might be penalized using this very forward value. However. AI OFF. for an A320. in order to be able to use the performance calculated for a 25% CG. a margin has to be applied on the calculated takeoff CG.2. Therefore. the calculation is always performed at the most forward-certified CG position. for aircraft having a naturally aft CG position (tail heavy aircraft).WEIGHT AND BALANCE ENGINEERING A. Zp 0ft The difference in 2nd segment gradient value may not seem significant. the calculated takeoff CG must be of at least 27%. Now. AC OFF. GENERALITIES • Influence on TOW A340 CONF 3.3 ∆TOW = 1366.e. Forward CG at CG 26%MAC TOW (kg) 256215. These “tail-heavy” aircraft usually have an aft takeoff CG position. TOD). 3. to take into account the errors in the determination of the CG position.1kg !For a given second segment climb gradient..2 257581.4. − at 25%MAC for the A320 − at 26%MAC for the A340. This means that their everyday performance is better than the certified performance for the most forward CG position. obstacle in take-off path). A second segment climb gradient of 5% is imposed (i. I. So a second CG position forward limit has been certified for these two aircraft. Basic and alternate CG positions From the 3 previous paragraphs it can be concluded that : The best takeoff performances correspond to an aft CG position. the basic certified CG is the aft CG (25%RC) and the alternate CG is the forward CG. it is preferable to establish the takeoff charts for that CG position. Takeoff charts and performances published in the FCOM are usually established for the basic CG position (25%) .A. performance corrections have to be applied. Getting to Grips with Aircraft Weight and Balance 81 WEIGHT AND BALANCE ENGINEERING . as the corrections given in the FCOM are conservative. should an A320 be operated with an alternate CG position.10.02. However. for the A320.Takeoff chart for an A320-232 If the CG position is forward to the 27% RC point. These are given in the FCOM 2. and if the operator does not have the take-off charts for a forward position. GENERALITIES a) A320 A320 Basic CG limits A320 Alternate CG limit Therefore. Take off charts and performances published in the FCOM are established for the basic CG position. 82 Getting to Grips with Aircraft Weight and Balance . GENERALITIES b) A340 A340 Basic and Alternate CG For the A340. an operator that wishes to benefit from the advantages of the alternate CG must establish the appropriate takeoff charts. the basic CG is the most forward CG and the alternate CG is the aft CG (26%). Influence on TOW Note : The following figures come from the PEP for Windows Take Off and Landing application. It takes into account all the limiting factors for take-off (runway length.WEIGHT AND BALANCE ENGINEERING A. Therefore. climb…). No corrections are given in the FCOM because the alternate CG performances are better than the basic CG performances. Calculations have been performed for a range of TORA and for different airfield altitude.1kg Conclusion Therefore. Getting to Grips with Aircraft Weight and Balance 83 WEIGHT AND BALANCE ENGINEERING . the envelope is narrower.8 ∆TOW = 1806. TOW AlternateCG − TOWBasicCG ∆TOW (%) = TOWBasicCG × 100 represents the difference in term of TOW when using the alternate CG for performance calculation instead of the basic CG. the operator can increase the aircraft takeoff weight.A. thus leading to more constraints on the loading aspect. GENERALITIES The following graphs show ∆TOW (%) as a function of the TORA length. For example: OAT Pressure Altitude (Zp) 20°C 0ft Runway length CG position Takeoff Weight (kg) • 3000m Basic 266013. A340-313 CONF 1+F We can notice that the difference in take off weights is all the more important with short runways and an elevated terrain. On the other hand. thus the payload or the range of the aircraft.9 Alternate 264207. by using the performances calculated for the alternate CG (A340) or for the basic CG (A320). 3. the lower the fuel consumption. the THS is set to an aircraft nose-up position that creates important lift degradation therefore creating important drag. This is due to the increasing balance arm between lift and weight. the Trimmable Horizontal Stabilizer (THS) creates a downward force. 84 Getting to Grips with Aircraft Weight and Balance . In the case of a forward CG position. the greater the counter moment necessary to keep the flight level. This drag will lead to an increase in fuel consumption. a) AFT CG POSITION THS Small balance-arm Lift Drag Weight Lift degradation b) FWD CG POSITION Lift Long balance-arm THS Drag Weight Lift degradation The further forward the CG. The further aft the CG. This additional force creates a pitch-up moment that counters the pitch-down moment due to the aircraft weight but also a drag increase which magnitude depends on the aircraft CG position.WEIGHT AND BALANCE ENGINEERING A. Reminder: In order to keep the airplane level. GENERALITIES 3. Impact on in-flight performance Let’s revert to the impact of the CG position on the forces applied on the aircraft and to the consequence it has on aircraft performance. The SR with a CG position at 27 % is taken as a reference. the more significant the fuel savings. The following graphs show the influence of the CG position on the aircraft specific range depending on the aircraft weight. the decrease or increase in fuel consumption according to the reference is significant. Getting to Grips with Aircraft Weight and Balance 85 WEIGHT AND BALANCE ENGINEERING . The aircraft therefore flies with an aft CG. for high weights and FL above 350. A310. For the other aircraft. thus giving better in-flight performance. a failure can prevent the fuel transfer and CG position control.A. the FCMC (Fuel Control and Management Computer) on the A330 and the A340 or the CGCC (Center of Gravity Control Computer) on the A300-600 and the A310 controls the CG position by transferring fuel in the trim tank. GENERALITIES c) Influence on fuel consumption This part refers to the Airbus “Getting to Grips with Fuel Economy” Brochure. Furthermore. they are not fitted with a trim tank. the curves all have a similar shape as these ones: For the A300-600. A330 and A340 types. when flying above FL350. on all the wide-body Airbus aircraft. This is due to a complex interaction of several aerodynamic effects. the further aft the CG. it is negligible The single aisle aircraft are not equipped with in-flight fuel transfer systems. the specific range variation can reach 2%. Contrary to the other aircraft. Thus. Whatever the influence of the CG position on specific range. loading is very important especially for high weights and for aircraft which have no automatic center of gravity management: we notice that. However. at a high weight. The data are expressed in Specific Range (SR) variations at cruise mach with a center of gravity of 20% and 35%. During cruise. specific range variations with respect to the CG position are random for the whole A320 family. 5 -2 160t 150t 140t 160t 140t 150t 130t 120t 110t 100t CG reference =27 % 310 330 350 370 390 100 110t 290 120t 130t CG=20 % Flight Level A340 2 1.5 0 -0.6 -2 310 330 CG reference = 27 350 370 390 CG = 20 % 230 t 240 t 210 t 190 t 200 t 220 t Flight Level Aircraft types A319/A320/A321 A330 A340 A310 A300-600 Fuel increment (Kg)/1000Nm between a 20% CG and a 35% CG Negligible 220 380 250 230 86 Getting to Grips with Aircraft Weight and Balance .4 0 290 -0.8 -1.5 -1 -1.2 -1.WEIGHT AND BALANCE ENGINEERING A. A300-600/A310 2. GENERALITIES d) Example On a 1000 NM stage length.5 SR variation (%) 1 0.6 1. the increases in fuel consumption when the center of gravity position is 20% with regards to the fuel consumption when the center of gravity position is 35% are summed up in the following table for an aircraft with a high weight and at a high flight level.5 CG=35% 2 1.4 -0.8 240 t 220 t 200 t 210 t 190 t CG = 37 % 230 t SR variation (%) 0.2 0. 2. Getting to Grips with Aircraft Weight and Balance 87 WEIGHT AND BALANCE ENGINEERING .4. For the other aircraft. Therefore. Landing distance or landing weight The aircraft operating speeds are referenced to the stalling speed. The further aft the CG. when determining the aircraft landing performance (LW. the Vapp value directly impacts the landing distance (or the landing weight).3Vs (1. Reminder: Forward CG position ⇒ High stall speed Aft CG position ⇒ Low stall speed. the calculation is always performed at the most forward-certified CG position. At landing: V App ≥ 1. 3. the greater landing weight (LW). Impact on landing performance 3. Vs Vapp LD So for a given Landing Distance: the lower the stall speed (Vs) value.1.A. the position of the CG is of no influence on landing performances as long as it stays within the certified limits. Only the A320 has two different certified CG. the smaller the LD (the greater the LW). a correction has to be made in the case of an alternate CG. for aircraft having a naturally aft CG position (tail heavy aircraft). The important performance as far as landing is concerned is the landing distance. GENERALITIES 3. everyday operations might be penalized using this very forward value.4. LD). As noted in the FCOM of the A320. Basic and alternate CG positions As for takeoff performances.23Vs1g ) Now.4. Summary H −armCG − H −armLeading Edge of MAC × 100 % MAC = Length of MAC Length of MAC × %MAC H −armCG = H −arm Leading Edge of MAC + 100 Stall speed The further aft the CG. the lower the fuel consumption. Landing The further aft the CG. the better the take off roll performance.5. GENERALITIES 3.6. the better the aircraft performance. 88 Getting to Grips with Aircraft Weight and Balance . The further aft the CG. 3.WEIGHT AND BALANCE ENGINEERING A. the smaller the LD (the greater the LW). Conclusion The best take-off performances will correspond to an aft CG position. the smaller the TOD (the greater the TOW). In-Flight The further aft the CG. the smaller the stall speed (Vs) value. the better the take off climb performance. Take off The further aft the CG. the CG has to stay within certain certified limits. However.A.10. the better the aircraft performances.02. Limitations) • Example : A320-212 The purpose of this chapter is to explain briefly how these limits are defined and why these limits vary according to the flight phase (take off. GENERALITIES 4. CERTIFIED LIMITS DESIGN PROCESS The previous chapter has dealt with the influence of the position of the aircraft center of gravity on performance. These limits are defined in the Limitations volume of the Flight Manual (Chapter 2. landing or in-flight) These limits are mainly due to: − structural limitations − handling qualities − a compromise between performances and aircraft loading Getting to Grips with Aircraft Weight and Balance 89 WEIGHT AND BALANCE ENGINEERING . The conclusion was that in general the further aft the CG.00) and are also in the Weight and Balance Manual (Chapter 1. R 25. (b) It must be possible to make a smooth transition from one flight condition to any other flight conditions without exceptional piloting skill. or (c) The extremes within which compliance with each applicable flight requirement is shown. (2) Climb.WEIGHT AND BALANCE ENGINEERING A.1.R 25. or strength.27: Center of gravity limits The extreme forward and the extreme aft center of gravity limitations must be established for each practicably separable operating condition. The following is an extract from the JAR 25. • J. (4) Descent.A. • J. and without danger of exceeding the airplane limit-load factor under any probable operating conditions including: (1) The sudden failure of the critical engine. (3) Level flight. including deployment or retraction of deceleration devices.A. alertness. (2) Configuration changes. (b) The extremes within which the structure is proven. Certification requirements Certain rules have to be respected when designing a CG envelope.143 : General (a) The airplane must be safely controllable and maneuverable during (1) Take-off. GENERALITIES 4. No such limits may lie beyond: (a) The extremes selected by the applicant. (5) Landing. Climb and Cruise Go-around Approach Take-off run Take-off rotation Landing 90 Getting to Grips with Aircraft Weight and Balance . In the following chapter all limitations are detailed by flight phase. 1.2. Nose gear strength : FWD limit (take off) c) Wing strength: The structural limits of the wing will have an effect on the CG limits at high weights. Main gear strength : AFT limit (take off) b) Nose gear Strength: " The more the CG is forward. Structural limitation a) Main gear Strength: " The further aft the CG is. GENERALITIES 4. the heavier the weight over the main gear " The strength of the main gear limits the aft position of the CG for high TOW.A. the more the weight over the nose gear " The strength of the nose gear limits the forward position of the CG for high TOW. Getting to Grips with Aircraft Weight and Balance 91 WEIGHT AND BALANCE ENGINEERING . Take-off Limitations 4.2. the lesser the adherence. Impossible rotation : FWD limit (take off) Tail strike : AFT limit (take off) 92 Getting to Grips with Aircraft Weight and Balance . The CG position can be moved forward until it reaches the point where rotation becomes impossible.WEIGHT AND BALANCE ENGINEERING A. the nose gear wheel must have enough adherence. If the correct trim setting is made prior to take-off. enough weight must be applied on the nose gear.2. To have an appropriate adherence. (This pitch up moment is due to the engines being located beneath the CG of the aircraft) The further aft the CG. GENERALITIES 4. This facilitates the rotation. the only possible means of controlling the aircraft on the ground is the nose gear steering. This adherence is further reduced during the take-off run when full power is applied on the engines. thus creating a pitch up moment. This leads to a difficult rotation. However. However. Taxi and Take-off run a) Nose Gear adherence: During taxi and at the beginning of the take-off run. an aft CG limit has to be established in order to prevent a tail-strike during the rotation. Note: A forward CG implies an A/C nose-up trim setting. flight-testing is performed with a forward CG position and an A/C nose-down trim setting (conversely with an aft CG position and an A/C nose-up trim setting) in order to cover the critical condition. the pilot will always have the same feel during rotation no matter the CG position. Nose gear adherence : AFT limit (take off) b) Take-off Rotation A forward CG means that the aircraft has a “heavy” nose. while an aft CG implies an A/C nosedown trim setting. when the speed of the aircraft is not sufficient for the rudder to be effective.2. An aft CG means that the aircraft’s nose is relatively “light”. In order to be effective. 1.3.A. 4. GENERALITIES 4.3. Static stability Definition: The static stability of an object depends on its tendency to return to its initial position after being slightly moved. it is equivalent to an increase in incidence or to the creation of a pitch up moment. the increase in lift creates a pitch down moment which reduces the incidence and brings the aircraft back to its initial conditions. Aircraft stability and maneuverability Limitations During all flight phases the aircraft must remain stable and maneuverable. The aircraft CG position has an influence on the aircraft static longitudinal stability in steady flight and during maneuvers. • Static stability When the aircraft is submitted to a gust. A lift increase is created at the aerodynamic center. If the CG is located forward of the aerodynamic center. Stable Unstable Neutral a) Longitudinal stability during steady flight • Aerodynamic center The increase (or decrease) in lift due to an increase (or decrease) in incidence (α) always applies on a fixed point of the wing. Pitch up moment due to the gust CG X Gust Pitch down moment due to the lift increase X Aerodynamic center ! The aircraft is stable Getting to Grips with Aircraft Weight and Balance 93 WEIGHT AND BALANCE ENGINEERING . This point is called the aerodynamic center. However. a significant elevator deflection will be necessary to give the aircraft a pitch up attitude. GENERALITIES If the CG is located aft to the aerodynamic center. The CG position can be moved forward until it reaches the point where the aircraft is very stable but cannot be maneuvered because the elevator has reached its maximum deflection. The CG must not be behind the aerodynamic center. Neutral Point : AFT limit (all phases) b) Maneuverability and elevator efficiency Considering the previous paragraph. approach. a compromise has to be reached between stability and maneuverability. Note : It is important to notice that the effects of the reduced maneuverability due to a forward CG are emphasized at low speeds when the elevators have a reduced efficiency. In order to be able to fly the aircraft. the lift and the weight have the same application point and there is no moment created the aircraft is neutral Hence the other name for the aerodynamic center: the Neutral Point. Elevator maximum deflection + Maneuverability margin : FWD limit (all phases) 94 Getting to Grips with Aircraft Weight and Balance . in the case of a very forward CG position. The CG is shifted aft until an appropriate maneuverability is found. The elevator efficiency limit is to be considered for all flight phases and it gives more constraining limit for take-off. the more forward the CG. and landing than for flight phases. Pitch up moment due to the gust Pitch up moment due to the lift increase Aerodynamic center ! The aircraft is unstable. the increase in lift creates a pitch up moment which adds to the initial pitch up moment due to the gust. the more stable the aircraft. Gust X X CG Note : If the center of gravity is located on the aerodynamic center.WEIGHT AND BALANCE ENGINEERING A. This brings the aircraft further away from its initial conditions. In order to compensate for this higher load factor. pull-out) and with the aircraft’s weight. GENERALITIES c) Longitudinal stability during maneuvers During flight the aircraft must remain stable during steady flight but also during different maneuvers.A. It is located behind the aerodynamic center (neutral point). This point varies with the type of maneuver (turn. If the CG is located on the maneuver point. Maneuver point The increase (or decrease) in lift due to an increase (or decrease) in load factor (n) applies on a fixed point of the wing. a reference point is established for which the maneuverability of the aircraft is reasonable : Point at 1° per g. Experience has shown that for stability reasons the CG must be located ahead of the point and at a considerable distance. the pilot must pull the stick. it appears that the higher the bank angle the higher the load factor. • Lift W Φ Apparent Weight = n.mg R = Turn radius W = Weight = mg Φ = Aircraft bank angle n = Load factor The load factor during a turn is: cos Φ = 1 n From the previous formula. This point is called the maneuver point. the elevator efficiency is infinite. • Point at 1° per g Example of a turn. In order to have an acceptable margin in regards to the maneuver point. Getting to Grips with Aircraft Weight and Balance 95 WEIGHT AND BALANCE ENGINEERING . This point is considered as an aft limit. thus increasing elevator deflection. weight and CG position. Drawing this graph for fixed conditions except CG position. gives the following: Elevator deflection (δ) δ n Load factor (n) δ40% δ30% δ10% 10% CG 40% CG 30% CG The further forward the CG position. the necessary elevator deflection to There is a CG position for which 1 degree of elevator deflection compensates a 1 g load factor (for which 1 degree of elevator deflection creates a 1g load factor).WEIGHT AND BALANCE ENGINEERING A. aircraft speed. This is the 1° per g CG. 1° per g point : AFT limit (all phases) 96 Getting to Grips with Aircraft Weight and Balance . the greater compensate on given load factor. Elevator deflection (δ) δ n=1g Load factor (n) δ40% δ=1° δ30% 10% CG 40% CG CG 1° per g 30% CG The experience has shown that the CG has to be ahead of the 1°/g CG. GENERALITIES For commercial aircraft the law that gives the elevator deflection (δ) necessary to compensate a given load factor (n) can be represented as follows : Elevator deflection (δ) δ δ1 δ2 Given CG position n1 n2 Load factor (n) This law depends on the type of maneuver. The position of the 1°/g point depends on the aircraft’s speed. 5g Load factor (n) Elevator deflection (δ) δ CG1 Maximum elevator deflection δmax CG2 CG3 CG3 : if aircraft CG is located on CG3 load factor 2. CG2 : if aircraft CG is located on CG2 load factor 2.5g cannot be reached whatever the elevator deflection is.A. These regulations require for maximum acceptable load factor with no structural damage of 2. Aircraft CG cannot be located forward of CG2. the maximum elevator deflection must not prevent the pilot from reaching the maximum load factor (pull-out cases for example). GENERALITIES d) Maximum elevator deflection and extreme load factor Civil aircraft are certified according to the JAR/FAR 25 regulations.5g can be reached for an elevator deflection lower than δmax. In order to keep full maneuverability capacity.5g is reached for elevator deflection δmax. This will therefore establish a forward CG limit as shown in the following figure: maximum load factor n = 2. CG1 : if aircraft CG is located on CG1 load factor 2.5g. Maximum elevator deflection (max load factor) : FWD limit (all phases) Getting to Grips with Aircraft Weight and Balance 97 WEIGHT AND BALANCE ENGINEERING . The combination of the two effects can lead to an important aircraft nose-up THS setting which can eventually lead to a THS stall. b) Approach + push-over When during approach the pilot excessively reduces the speed. The more aft the CG. Alpha Floor Protection Alpha floor protection configuration: high angle of attack. A forward CG position increases the pitch-down moment and is also countered by an aircraft nose-up THS setting. The more the CG is aft. In case of a forward CG position countered by an aircraft nose-up THS setting. GENERALITIES 4. Go Around Setting the engines at full throttle creates a significant pitch-up moment which must be compensated by the elevator.3.WEIGHT AND BALANCE ENGINEERING A.4. The CG position can be moved aft until it reaches the point where the pitch-up moment cannot be compensated anymore by the elevator deflection. This configuration gives the aircraft a pitchdown attitude. THS stall limit : FWD limit (flight and landing) (and take off for final approach in case of emergency landing) 4.2. This pitch-down moment is countered by an aircraft nose-up THS setting. the higher the pitch. Final Approach Limitations 4. Low speed implies low elevator efficiency. That will limit the aft position of the CG more than the go around limitation.1. low speed and TOGA power. Go around : AFT limit (flight and landing) (and take off for final approach in case of emergency landing) 4. he will push the stick (“push-over”).up moment. the higher the pitch-up moment. the flaps and slats are extended. Alpha floor protection : AFT limit (flight and landing) (and take off for final approach in case of emergency landing) 98 Getting to Grips with Aircraft Weight and Balance .4. TOGA implies high pitch-up moment.4. THS stall a) Standard approach During approach. this procedure may lead to the THS stall because of the aircraft attitude change. The CG position can be moved aft until it reaches the point where the pitch-up moment cannot be compensated anymore by the elevator deflection. in order not to stall and regain a proper approach speed.4. Limitation summary TAKE OFF FWD Nose gear strength (high weights) Impossible rotation Elevator maximum deflection + maneuverability margin Maximum elevator deflection (max load factor) AFT Main gear strength (high weights) Nose gear adherence Tail strike Neutral Point 1° per g point IN FLIGHT FWD Elevator maximum deflection + maneuverability margin Maximum elevator deflection (max load factor) AFT Neutral Point 1° per g point THS stall limit Go around Alpha floor protection AFT Main gear strength Neutral Point 1° per g point THS stall limit Go around Alpha floor protection LANDING FWD Nose gear strength Elevator maximum deflection + maneuverability margin Maximum elevator deflection (max load factor) Getting to Grips with Aircraft Weight and Balance 99 WEIGHT AND BALANCE ENGINEERING . elevator maximum deflection and aircraft maneuverability limit the CG position forward.5.6.5.2. Landing Limitations 4. GENERALITIES 4.A. Thus. when the elevator must enable the pilot to flare out.2) but it is important just before landing. they are usually less limiting as the aircraft is less heavy then at take off.1.3. Maneuverability and elevator efficiency This limitation concerns all flight phases (ref. Main gear strength : AFT limit (landing) Nose gear strength : FWD limit (landing) 4.5. Elevator maximum deflection + Maneuverability margin : FWD limit (landing) 4. Structural limitations Landing structural limitations are similar to take off ones. at low speed. B.1.2. 7. On the other hand. Those limitations are classified as handling quality and structural limitations As seen previously (in “Influence of CG Position on Performance”).7. It would penalize the loading to set a more aft limit and in this case. GENERALITIES 4. !From the performance point of view the forward limit of the envelope must stay as aft as possible. the forward limit corresponds to the handling qualities limitations. it : l lim gth tura stren c Stru gear o se N H an For some aircraft and for high TOW the compromise Performance/Loading tends to favour performance more than for low TOW. In other words. Take off limits a) Forward limit The design of the forward limit takes into account the following: − Nose gear strength − Take-off rotation − Maneuverability (efficiency of the elevator when aircraft in-flight) − Flaps/slats extension (final approach in case of emergency landing). as it corresponds to the worst CG position. the handling qualities are ahead of the retained limit.WEIGHT AND BALANCE ENGINEERING A. as far as performances are concerned. in order to facilitate the loading of the aircraft. 100 dlin ality g qu ts limi Limit shift due to the compromise between performance and loading g e mis /Loadin pro e Com rmanc fo Per Getting to Grips with Aircraft Weight and Balance . Certified limits definition 4. the envelope could be widened without any impact on handling quality and aircraft safety. the handling quality of some “nose heavy” aircraft are already rather limiting. ! From the loading point of view the forward limit must not be too aft. However. the envelope must be as wide as possible (both aft and forward).1. In aircraft operations the TOCG positions in this area are hardly reached because of loading procedures and fuel vector shape. If the envelope is too narrow. The retained limit is a compromise between loading and performance. In most of the cases. the FWD CG limit is the reference CG for aircraft performance. the operators will have to be very careful on where they locate the freight in the holds and on how they sit their passengers in the cabin. Only the structural limitations and the handling quality will be taken into account when establishing the aft limit of the CG envelope. Those limitations are classified as handling quality and structural limitations !From the performance point of view the aft limit of the envelope must stay as aft as possible. ! From the loading point of view the aft limit must be as aft as possible. For aft CG limits. GENERALITIES b) Aft limit The design of the aft limit takes into account the following: − Main gear strength − Nose gear adherence − Take-off rotation (Tail strike) − Stability in steady flight and during maneuvers − Go-around and Alpha Floor (final approach in case of emergency landing).A. there is no need for a compromise between loading operations and performance. : it gth lim ren al st ur r ct ea ru g St ain M : ce ity en al er qu h g ad lin ear nd g Ha ose N Han d Low ling qu a (Alp speed c lity : ha f loor onfigur at or G o ar ion oun d ) Getting to Grips with Aircraft Weight and Balance 101 WEIGHT AND BALANCE ENGINEERING . Landing limits The limitations that apply for take-off also apply for landing. so the aft landing envelope is : − either superimposed of the take off one. (fig1) − or set aft of the take off one (fig 2).2. b) Aft limit The aft landing envelope could usually be set aft of the take off one (less restrictive) .7. a) Forward limit The forward landing envelope is superimposed on the take off one. t Fligh Fig1 Landi ng Fig2 102 Getting to Grips with Aircraft Weight and Balance Ta ke -o Landi ff ng Ta ke -o ff Fligh t .WEIGHT AND BALANCE ENGINEERING A. Nevertheless at landing the aircraft weight is lower than at take off so some limitations are not as restrictive as for take off. Depending on the aircraft type and on the fuel vector shape it might be useful or not to extend the landing aft limit. GENERALITIES 4. In addition the nose wheel adherence does not generate a limitation. During cruise (flight phase).3. the passenger movements modify the aircraft CG. Usually the in-flight phase is less limiting than the take-off one as limiting factors such as high weights. Indeed.7. Note : the nose gear adherence limitation is not taken into account for the determination of the aft limit.A. − Choosing the in-flight envelope of the same size as the take-off one is too restrictive. GENERALITIES 4. − Opening this envelope as much as possible is useless as the CG is constrained by the T/O phase. − Stability in steady flight and during maneuvers − Go-around and Alpha Floor Those limitations are classified as handling quality and structural limitations !From the performance point of view the forward and aft limit of the envelope must stay as aft as possible to reduce fuel consumption. low speeds and TOGA are specific to take-off phase. In flight limits a) Forward limit The design of the forward limit takes into account the following: − Fuel consumption − Efficiency of the elevator − THS stall b) Aft limit The design of the aft limit takes into account the following: − Point at 1° per g. That is why the in-flight envelope is usually deduced from the take-off one and wider from roughly 1 or 2%. Getting to Grips with Aircraft Weight and Balance 103 WEIGHT AND BALANCE ENGINEERING . ! From the loading point of view the operational limit must be as wide as possible. Consequently. so during this phase to check the aircraft CG against the in flight envelope those slight CG position modifications must be taken into account. the in-flight envelope is chosen with respect to the take-off one. because of the passenger movements during cruise the in flight envelope becomes more limiting than the take off one. 1. SUMMARY : CG ENVELOPES 4. LANDING Structural limitation: Nose gear strength Maximum structural Take Off Weight Structural limitation: Main gear strength Maximum structural Landing Weight Compromise Performance/Loading Handling quality : Nose gear adherence Handling quality : Alpha floor or Go around 104 Getting to Grips with Aircraft Weight and Balance .WEIGHT AND BALANCE ENGINEERING A. GENERALITIES 4.8. TAKE-OFF Maximum structural Take Off Weight Structural limitation: Nose gear strength Structural limitation: Main gear strength Compromise Performance/Loading Handling quality : Alpha floor or Go around Handling quality : Nose gear adherence 4.2.8.8. 4. IN FLIGHT Maximum structural Take Off Weight Structural limitation: Main gear strength Structural limitation: Nose gear strength Handling quality : Alpha floor or Go around Compromise Performance/Loading Handling quality : Nose gear adherence 4.A. GENERALITIES 4.8.8. AIRCRAFT CERTIFIED ENVELOPE Getting to Grips with Aircraft Weight and Balance 105 WEIGHT AND BALANCE ENGINEERING .3. . which gives the results of the aircraft weighing (Operating Empty Weight and corresponding CG position). This document is divided into three sections : − 0. which contains all the pages describing the manual (Table of contents. which describes generic weight and balance data for the concerned aircraft. − 2.B. balance and loading are concerned.00 Arrangement of introduction pages. Weight and balance control. Getting to Grips with Aircraft Weight and Balance 107 WEIGHT AND BALANCE ENGINEERING . It is the document released by the manufacturer and given to the operator with the aircraft that contains all necessary information to determine loading instructions or to produce the Load and Trim Sheet. Aircraft weighing reports. WEIGHT AND BALANCE MANUAL WEIGHT AND BALANCE MANUAL INTRODUCTION The Weight and Balance Manual is the reference as far as weight. − 1. List of figures …). The purpose of this chapter is to present the information included in the WBM. This graph enables to determine the correct trim setting according to the aircraft CG prior to take-off.00 : − An important graph on page 1.05.09: the stabilizer trim wheel setting. 1. WEIGHT AND BALANCE MANUAL 1. SECTION 1 : WEIGHT AND BALANCE CONTROL This section is divided into ten parts. different weight definitions and conversion factors. 1.00. Then it provides drawings and a description of the general characteristics of the aircraft.00: GENERAL This part of the WBM presents first generic information such as a list of abbreviations.WEIGHT AND BALANCE ENGINEERING B.1.00. WEIGHT AND BALANCE MANUAL B. main aircraft dimensions Two other pieces of information can be found in section 1. 108 Getting to Grips with Aircraft Weight and Balance . • ex A330-200: page 1. 00. WEIGHT AND BALANCE MANUAL − The effect of moving components (1.10) is used to determine the influence of the landing gear retraction and/or flaps/slats extension on the aircraft CG position (see B3. • AIRCRAFT WEIGHT (TONS) ex : A330-200 Other limitations are linked to payload carriage: − the permissible limits for shear loads and bending moments due to payload (1.e.2.10. These certified CG limits are the starting point for the determination of the operational flight envelope.02).1 Principle of Error calculation). the maximum weights (1.B.10. Getting to Grips with Aircraft Weight and Balance 109 WEIGHT AND BALANCE ENGINEERING .10: LIMITATIONS This chapter deals with the different weight and balance limitations applied to the aircraft.04 floor loading limits).03) and − the maximum weights that can be transported or loaded on cabin floor or on cargo compartment floor (1.10. The first ones are certified limits.10. • ex : A330-200 1.01) and the certified CG limits (charts and diagrams 1. 1. i. 05 to 1.10.10.07 deal with cargo compartment loading and give rules and recommendations for weight limitation.10 : aircraft stability on wheels 110 Getting to Grips with Aircraft Weight and Balance .09 : aircraft stability on jacks − 1. load factors. maximum weight.WEIGHT AND BALANCE ENGINEERING B. location.08 : maximum jacking loads − 1. …) and additional limitations in case of latch failure(s).10.10. • ex : A330-200 Last paragraphs deal with aircraft stability during weighing and loading: − 1. WEIGHT AND BALANCE MANUAL • ex : A330-200 − the paragraphs 1.10. tying down of each load type (number of containers. and all fuel weights are based on a fuel density of 0.782 kg per liter unless otherwise specified.20. density and weight All fuel quantities in this manual are in liters.B. 1. It is important to note the value of the density used in the WBM.3. The first part (1. A330/340 family • A300. Getting to Grips with Aircraft Weight and Balance 111 WEIGHT AND BALANCE ENGINEERING . fuel circulation within the different tanks during refueling and defueling.20: FUEL This chapter of the WBM describes the influence on the aircraft CG position of the use of the fuel systems (refueling and fuel burn).02) of the chapter details the aircraft refueling of tanks sequence : • ex : A330-200 Using this sequence it is possible to determine for each fuel quantity on board the aircraft.20. A320 family. WEIGHT AND BALANCE MANUAL 1. The last part of the introduction is the following : • A310. because variations in actual fuel density due to specific gravity and temperature may result in large weight variations relative to those given in the manual. The second part (1. A300-600 C. how much fuel each tank contains.01) describes briefly the aircraft fuel system : the arrangement of the tanks and the collector positions. Fuel volume. () that depend on fuel density have to be recalculated The third part of the chapter details the usable fuel (1. ' and ( are variable depending of fuel density. ' and with the corresponding fuel quantities.785 kg/l) 0 kg in center tank 2 400 kg in trim tank As noted below the graph in this example : − Points − This explains why for one selected fuel quantity there might be more or less fuel in a given tank depending on the fuel density value. $ and % are fixed in weight (kg or lb) irrespective of fuel density. a second graph presents the variations of the CG position of the fuel loaded on aircraft and a table gives all the coordinates of this graph. WEIGHT AND BALANCE MANUAL • ex : A330-200 Selected Fuel quantity 65 000 kg 25 650 kg per inner tank outer full : 2 865 kg per outer tank (density : 0. Note : the table and the corresponding graph are designed for the WBM standard fuel density (0.785 kg/l or 0.20. whenever this table needs to be done for another density all break #. In addition to the above graph. points (cf example points &. A310 and A300-600R aircraft that is to say aircraft with fuel tank in the horizontal stabilizer.782 kg/l). 112 Getting to Grips with Aircraft Weight and Balance . This is particularly appreciable for A330/340.WEIGHT AND BALANCE ENGINEERING B. Points &.03) quantities and the corresponding H-arm values for each tank. This paragraph data is independent of the fuel density value. 20.20. WEIGHT AND BALANCE MANUAL • ex : A330-200 Note 1: For inner and outer tanks the quantity is given per side.20.B. Note 2: In addition to the tables graphs showing the Fuel CG H-arm and Y-arm are provided.05 : Unpumpable fuel − 1.06 : Defueling procedure prior to weighing Getting to Grips with Aircraft Weight and Balance 113 WEIGHT AND BALANCE ENGINEERING . Last paragraphs deal with: − 1.04 : Unusable fuel − 1. 1. The drawing of the cabin layout is on page 3 of section 1. • ex : A330-200 1.40.05) describes the method to determine the influence of in flight movement on the aircraft CG position.40. 114 Getting to Grips with Aircraft Weight and Balance .30: FLUIDS This section contains information on the fluids on board the aircraft: − Engine fluids − APU oil − Hydraulic systems fluids − Potable water − Toilet fluids The WBM gives information on the weight and the H-arm of the fluids. the cabin crew and the passengers. 1.4.03. WEIGHT AND BALANCE MANUAL 1. In section 1.04 the position of all passenger seat rows is given.WEIGHT AND BALANCE ENGINEERING B.40: PERSONNEL This section contains weight and balance information for the flight crew. The CG of each person is considered to be in the middle of the seat. Last section in-flight movements (1.40.5. For each category the H-arm of each person is given. After a brief description of the cargo area division in holds. Getting to Grips with Aircraft Weight and Balance 115 WEIGHT AND BALANCE ENGINEERING .60:04 aft hold.B. The last sections deal with methods and recommendations for cargo loading : − Tie down method (method used to determine the number of tie down points to be used for each cargo weight). the first section (1.6.10 LIMITATIONS. Note : the above mentioned paragraph can be present or not depending on the cargo option of the aircraft.03 forward hold. 1. cabin overhead stowage compartment.60.05 bulk hold) : − Description of each loading device that can be loaded in the hold with its dimensions and position. boilers…). cabin stowage compartments. 1. In short. − Live animals transport. it describes all locations where some weight can be added in the upper deck area. − Pallet transport. − Limitations concerning package dimensions. − Container transport. WEIGHT AND BALANCE MANUAL 1. Note: for some stowage areas the maximum load value includes the stowage device weight (galleys.…). For each location. − Split engine transportation. Note : all information on cargo weight limitation is provided in chapter 1. Then each cargo hold is fully described (1.50: INTERIOR ARRANGEMENT This section on the WBM contains information on the different stowage capacities in the aircraft: the flight compartment stowage. − Tie down points identification and positions of the nets for bulk loading.02) details the cargo hold doors opening sizes and stations. toilets and the cabin stowage compartments. 1.60.60: CARGO This section of the WBM deals with cargo loading.60. the CG position of the weight is given as well as the maximum weight allowed. galleys with their contents (trolleys. 1.7. 1. − Gantry pallet transportation. WEIGHT AND BALANCE ENGINEERING B. WEIGHT AND BALANCE MANUAL • Ex : A330-200 Average H-arm positions of the different ULD configurations Different ULD types usable in the hold with the appropriate position 116 Getting to Grips with Aircraft Weight and Balance . 80.9.90: Examples Note 1 : the examples presented in this section are valid only for the balance scale presented in 1.80. flaps…).02) and then gives all formulae necessary to the calculation of the weight and CG of an aircraft weighed on wheels (1.B. Section 1. and CG calculations.80. 1.8.05). These equipment are parts of the wing (slats. 1. Getting to Grips with Aircraft Weight and Balance 117 WEIGHT AND BALANCE ENGINEERING . It first describes the Weighing point locations (1. part of the engine pylon and nacelle. doors. weighing on jacks or on wheels. Note 2 : the Typical loading diagram (1.90.04) is drawn on the aircraft certified limits diagram.80: ACTIONS ON GROUND This section contains information on jacking points.00.06 gives the Equipment/component removal list: information on weight and Harm of equipment normally removable from the aircraft for maintenance purposes. It should be drawn on the operational limits diagram to take into account the aircraft CG movements due to CG determination errors and moving part transfer during flight.05.80.… 1. WEIGHT AND BALANCE MANUAL 1.04) and weighed on jacks (1. WEIGHT AND BALANCE ENGINEERING B. 118 Getting to Grips with Aircraft Weight and Balance .10 : Delivery weighing report which contains data to establish aircraft Operational Empty Weight (OEW) and Manufacturer Empty Weight (MEW) and corresponding CG positions. SECTION 2 : WEIGHT REPORT This chapter contains the documents supplied with the aircraft at delivery: − 2.20 : Weighing check list which describes each item position and unit weight. In case the item is not present during aircraft weighing it should be mentioned in this section. WEIGHT AND BALANCE MANUAL 2. − 2. INDEX + Aircraft CG (%MAC) NOTES MTOW = 230000 kg 230 220 210 200 Aircraft Weight (kg x 1000) 190 MLW = 180000 kg 180 170 160 150 140 130 OPERATIONAL LIMITS 120 110 TAKEOFF ZFW MZFW = 168000 kg TAKEOFF CG % MAC ZFW CDU INPUT WEIGHT (kg x 1000) INDEX 70 80 90 100 110 120 130 140 .33. SIGNATURE : PASSENGERS ZERO FUEL WEIGHT FROM : TO : TOTAL FUEL ONBOARD TAKEOFF WEIGHT INDEX CORRECTION ZONES ZONES WEIGHT DEVIATION (kg) E F G H PAX E OA (18 PAX) ROW 1 TO 3 A G1c Ln 1 2 3 G2 1 A G1 2 3 Lk1 A G3 A 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Lo A 1 2 3 A Lh1 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 A Lh2 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 G7 12 14 15 16 17 18 A330-243 VERSION : 18 BC-264 YC ± = + x 8 4 = + = + = DRY OPERATING WEIGHT INDEX F OB (152 PAX) ROW 12 TO 31 19 20 21 22 23 24 25 26 27 28 29 30 31 Lk2 A Lp 32 33 34 35 36 37 38 39 40 41 42 43 44 45 32 33 34 G OC (112 PAX) ROW 32 TO 46 35 36 37 38 39 40 41 42 43 44 45 46 G5 A G6 A BASIC INDEX CORRECTION DRY OPERAT. AIRCRAFT CG 18 %MAC % MAC PITCH TRIM 20 Constant 7 22 6 24 5 26 4 28 3 30 2 32 1 34 0 36 38 Constant 40 . BALANCE CHART DESIGN BALANCE CHART DESIGN INTRODUCTION The purpose of this section is to detail the whole process that leads to the production of a balance chart and of the corresponding AHM560.1555) x W + 100 5000 CAPT. LOAD and TRIM SHEET DRY OPERATING WEIGHT CONDITIONS WEIGHT (kg) H-arm (m) AIRCRAFT REGISTER : DRY OPERATING WEIGHT WEIGHT DEVIATION (PANTRY) DATE : PREPARED BY : CORRECTED DRY OPERATING WEIGHT CARGO FLT Nbr : I= (H-arm . .22 H CARGO 1 (18869 kg) 2 3 (15241 kg) 4 5 (3468 kg) INDEX CORRECTION ZONES CARGO 1 CARGO 2 CARGO 3 CARGO 4 CARGO 5 CABIN OA CABIN OB CABIN OC Nbr WEIGHT(kg) 70 80 CORRECTED INDEX 90 100 110 120 ALL WEIGHTS IN KILOGRAMS 130 140 INDEX 500 kg 500 kg 500 kg 500 kg 250 kg 10 PAX 40 PAX 15 PAX FUEL INDEX SEE TABLE OVERLEAF 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 .30 +1.22 -1.82 +0. then the calculation of the influence on aircraft CG of any item loading and finally the method to determine the aircraft operational limits. Nose Up Nose Down Getting to Grips with Aircraft Weight and Balance 119 WEIGHT AND BALANCE ENGINEERING . WEIGHT DEVIATION +300 kg -300 kg ZONES E -1. It first describes the calculation tools that are used (moment and index).82 G +1.30 F -0.C. . Moment a) 1 Item moment : Moment = Weight × Distance from item CG position to Reference axis W = item weight H-arm = item CG position H-armReference axis CG Origin H-arm = 0 Moment = Weight × (H − armItem − H − armReference axis ) Note : in the whole process the moment notion has been simplified. fuel. MOMENT AND INDEX DEFINITIONS The purpose of the balance chart is to give an “easy way” to determine the influence on aircraft CG position of the loading of any item (passenger. H-arm b) (Item1 +Item2) moment Moment (Item1 +Item2 ) = Moment Item1 + Moment Item2 Getting to Grips with Aircraft Weight and Balance 121 WEIGHT AND BALANCE ENGINEERING . cargo load. Note : As common vocabulary uses Weight term instead of Mass. In this case the Force is simplified to the Mass of aircraft. BALANCE CHART DESIGN 1. BALANCE CHART DESIGN C. normally a moment is determined by a Force multiplied by a distance. This “easy way” consists in introducing the notions of aircraft moment and item moment and consequently in defining the index. 1.C.1. …). the wording is kept throughout the document. a common reference axis has to be fixed. For all Airbus current aircraft the reference has been set for standard balance chart design at 25% of Mean Aerodynamic Chord as it is approximately in the middle of the certified envelopes of Airbus aircraft.H-armReference axis) H .WEIGHT AND BALANCE ENGINEERING C.armItem + Additional item = W × H .H-armReference axis) Momentitem+additional item = (W+w’) x (H-armItem+Additional item .H-armReference axis) Momentadditional item = w’ x (h-armAdditional item .H-armReference axis) + w’ x (h-armAdditional item . BALANCE CHART DESIGN c) HOW TO DETERMINE THE CG position of the set (Item+Additional item) ? Item weight = W CG position = h-armItem Additional item weight = w CG position = h-armAdditional item Item + Additional item Final Weight = W + w’ Final CG position = h-armItem + Additional item Origin H-arm = 0 Final CG position H-armReference axis h-armAdditional Item h-armItem Momentitem = W x (H-armItem .armItem + w'×H − arm Additional Item W + w' d) ZFCG and TOCG determination So to determine the aircraft Zero Fuel and TakeOff CG positions we can use the following : ZFCG = Moment empty aircraft + Moment on board passenger + Moment loaded c arg o WEIGHT Zero Fuel TOCG = Moment empty aircraft + Moment on board passenger + Moment loaded c arg o + Moment fuel on board WEIGHTTakeoff To calculate each moment individually. 122 Getting to Grips with Aircraft Weight and Balance .H-armReference axis) MomentItem+Additional Item (W + w’) x (H-armItem+Additional item .H-armReference axis) = = MomentItem + MomentAdditional Item W x (H-armItem . Two constants appear in this formula: C: constant that allows having more workable figures. If an item is loaded forward to the reference the resulting moment will be a positive value (>0). the figures obtained when calculating each moment individually are very large and consequently not easy to manipulate. Note 2 : For the A380 as the certified limits will be more aft than for the other Airbus fleet aircraft the reference will be set at 35% of Mean Aerodynamic Chord. K: constant that is set so that the final ZF and TO index value is never negative. Index a) Definition The index is a means to both reduce figures manipulated by the user. 1.in). In the following chapter it may appear as IU : Index Unit. and represent the weight and the location of each item. BALANCE CHART DESIGN Hitem Reference axis Origin H-arm = 0 25%MAC H-arm = H25 Item Weight = W H-arm = Hitem Moment item = W × (H − arm item − H 25 ) Note : If an item is loaded forward to the reference the resulting moment will be a negative value (<0). Airbus applies the following constants to its aircraft: A300B2 / A300B4 C (kg. But usually.m) (lb.m or lb.2. Index item = I item = Moment item W × (H − arm item − H ) +K = +K C C It is a value with no unit. In order to reduce the figures of moments to a more workable magnitude.C. we use the Index. The value of these constants depends on the aircraft type and on the airline policy. Nevertheless.in) K 2 000 200 000 50 A300-600 / A310 1 000 100 000 40 A318 500 40 000 50 A319 / A320 / A321 1 000 100 000 50 A330 / A340 2 500 200 000 100 A340-500 / A340-600 5000 500 000 100 Getting to Grips with Aircraft Weight and Balance 123 WEIGHT AND BALANCE ENGINEERING . It has the same units as the moment (kg. the index variation due to this specific loading can be determine ∆IndexAdditional Item = MomentAdditional Item C c) ZF Index and TO Index determination So to determine the aircraft Zero Fuel and TakeOff index we can use the following : ZF Index = Index empty aircraft + ∆Index on board passenger + ∆Index loaded c arg o TO Index = Index empty aircraft + ∆Index on board passenger + ∆Index loaded c arg o + ∆Index fuel on board Then it is possible to determine the moment corresponding to the resulting index and then the corresponding CG position. fuel. BALANCE CHART DESIGN Weight × (H − armItem − H 25 ) + K = Weight × (%MAC item − 25 ) × C ′ + K C Length of RC with : C ′ = 100 × C Index = b) ∆Index : Index variation for any additional item loaded Note : two different index formulae can be used depending on the unit of item H-arm : length (m or in) or %MAC. cargo. For any item loaded on board the aircraft. the method to determine the ∆Index for any item loaded on the aircraft is detailed (passengers. In the following paragraph. additional catering…). 124 Getting to Grips with Aircraft Weight and Balance .WEIGHT AND BALANCE ENGINEERING C. ∆Index for one item ∆Index item = Moment item Weight item × (H − arm item − H 25 ) = C C ∆Index is calculated for any person or item that can be loaded on board the aircraft. 2. BALANCE CHART DESIGN 2.1. K = 100 1× (9.8 − 33. ∆Index for additional crew member WBM 1.m.794 IU ∆Index(1kg)Flight Crew Third occupant = Note 1: the calculation principle is the same for cabin crew members. INDEX VARIATION CALCULATION (∆INDEX) ∆ The index variation calculation is used to fill in the AHM560 document and to design the Balance Chart. In the AHM560.1555 m.8 − H25 ) (9.1555 ) = = −0. 2. for cockpit crew members information is displayed as shown below. Weight item = 1 and H − armitem is read in the Weight and Balance Manual. Note 2: in the AHM560. • Ex : A330-200 additional Flight crew member H25 = 33.40 Personnel chapter gives information on the position of all the flight and cabin crew seats. ∆Index figures are usually given for 1 kg (or 1 lb) of weight. Getting to Grips with Aircraft Weight and Balance 125 WEIGHT AND BALANCE ENGINEERING . C = 2500 kg.00934 IU / kg C 2500 So for one additional person in the cockpit (85 kg) : ∆Index (85kg) = −0.C.2. H − armCockpit average = H − armCaptain + H − armFirst Officer + H − armThird occupant + H − armFourth occupant ∆Index(1kg)Cockpit average = (H − armCockpit average − H25 ) C 4 2. • Ex : A330-200 galleys capacities and positions H25 = 33. ∆Index for additional weight on the upper deck WBM 1. toilet.3.m. ∆Index (1kg)G1b = C = 2500 kg. 126 Getting to Grips with Aircraft Weight and Balance . overhead stowage compartments.714 − 33.1555 ) = = −0. K = 100 1× (10.807 -0.50 Interior Arrangement chapter describes the different stowage capacities in the flight and cabin compartments.1555 m. the galleys and the toilets. cabin stowage compartments.00898 IU / kg C 2500 Note : Each item H-arm represents the load CG position.00952 Maximum number of cockpit seats Index influence per 1 kg The ∆Index value is given for the average H-arm of the 4 cockpit positions. 5. galleys.1 COCKPIT Number of seats and average station Length of arm from reference station meters 4 Remarks: -23.WEIGHT AND BALANCE ENGINEERING C. it is usually located at the item barycentre.714 − H25 ) (10. BALANCE CHART DESIGN 5. This section gives information on the H-arm of each item: flight compartment stowage. 1555 ) = = −0.C.5 − H25 ) (16. H25 = 33. C = 2500 kg.m.520 − H25 ) (14.5 m (H − arm C1 × 2 + H − arm C2 × 2 + K + H − arm C6 × 2 ) + (H − arm W 1 × 4 + K + H − arm W 6 × 4 ) 1× (16.885 − H25 ) (13. So the aircraft cabin is divided into several sections (usually 2 to 4 parts) and a generic influence is determined for each cabin.5 − 33.1555 ) = = −0. • Ex : A330-200 Cabin OA influence CABIN OA CABIN OB CABIN OC First step is to determine each cabin weighted average H-arm. H − arm OA = 32 = 16. BALANCE CHART DESIGN 2. nevertheless on the manual balance chart it is not possible to take into account the ∆Index of each individual row.00745 IU / kg C 2500 These ∆Index values per kg are presented in the AHM560. • Ex : A330-200 seat row positions Note : passenger seat CG is usually located in the middle of the seat.885 − 33.520 − 33. the ∆Index is calculated.4. K = 100 ∆Index(1kg)Center seat row 1 = 1× (13.1555 ) = = −0. ∆Index for passenger boarding WBM 1. For each window seat row and each center seat row.40 Personnel chapter gives information on the H-arm of each passenger seat row CG position.00771 IU / kg C 2500 ∆Index(1kg) Window seat row 2 LH = ∆Index(1kg) Window seat row 2 RH = 1× (14.1555 m.00666 IU / kg C 2500 ∆Index (1kg)Cabin OA = Getting to Grips with Aircraft Weight and Balance 127 WEIGHT AND BALANCE ENGINEERING . ∆Index for cargo loading WBM 1.607 − H25 ) (37.1555) ∆Index(1kg) 31P Pallet 88 " = = = +0.607 − 33.60 Cargo chapter gives information on the H-arm of cargo CG position for each cargo type (container. pallets or bulk).00178 IU / kg C 2500 Pallets 88” : H. • Ex : A330-200 AFT cargo compartment positions Position 31 Containers : H-armaverage=37.WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN 2.607 m ∆Index(1kg)31 = ∆Index(1kg)31R = ∆Index(1kg)31L = 1× (37.armaverage=37.958 − H25 ) (37.958 m 1 × (37.958 − 33.00192 IU / kg C 2500 128 Getting to Grips with Aircraft Weight and Balance . For each cargo type on each cargo position the ∆Index is calculated.1555 ) = = +0.5. These ∆Index values per kg are presented in the AHM560. Containers : Max weight = 2x1587 kg = 3174 kg Pallets 88” : Max weight = 4626 kg Pallets 96” : Max weight = 5103 kg HC arg o3 = (H31 + H32 + H33 ) × 3174 + (H31P 88" + H32P 88" ) × 4626 + (H31P 96" + H32P 96" ) × 5103 3 × 3174 + 2 × 4626 + 2 × 5103 = 39.1555 ) = = +0. BALANCE CHART DESIGN Pallets 96” : H-armaverage=38. nevertheless on the manual balance chart it is not possible to take into account the ∆Index of each individual cargo position and each individual cargo type.C.00243 IU / kg C 2500 Getting to Grips with Aircraft Weight and Balance 129 WEIGHT AND BALANCE ENGINEERING .225 − 33.095 − 33.1555 ) ∆Index(1kg)31P Pallet 96 " = = = +0.095 − H25 ) (38.095 m 1× (38. • Ex : A330-200 AFT cargo holds CARGO HOLD 3 CARGO HOLD 4 First step is to determine each cargo hold weighted average H-arm. it is usually located at the ULD barycentre for non bulk cargo and at the cargo position surface barycentre for bulk cargo. So the cargo loaded is divided into cargo holds and a generic influence is determined for each hold.00198 IU / kg C 2500 Note : Each item H-arm represents the load CG position.225 − H25 ) (39.225 m ∆Index (1kg)C arg o3 = 1× (39. WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN 2.6. ∆Index for fuel loading Weight & Balance Manual section 1.20 (“Fuel”) provides with information on the aircraft fuel tanks, the H-arm of the fuel in each individual fuel tank for each fuel quantity and describes the automatic refueling sequence. From this data it is possible to determine for each total fuel quantity, on the first hand the fuel quantity that will be in each tank after the refueling sequence is completed and on the second hand the corresponding total fuel CG position. Last, for each total fuel quantity the ∆Index is calculated. a) Determination of the fuel distribution per tank after the refueling process First it is necessary to know the fuel quantity in each tank depending on the total selected fuel on board. Thanks to the automatic refueling system, the fuel dispatch among the several tanks of the aircraft is automatic and leads always to the same fuel distribution in each tank for a given total fuel quantity and a given fuel density. • Ex : WBM A330-200 refueling sequence In WBM section 1.20.02 page 1, a graph (established at the standard fuel density of 0.785 kg/l) and a written procedure (irrespective of fuel density) summarize the refueling sequence: from a given total fuel quantity (in kg), the fuel quantity that will be dispatched by the automatic refueling system in each individual tank can be deduced. For instance the automatic refueling procedure on A330-200 aircraft (equipped FCMS standard 7.0) is: - inner tanks refueled up to 3000kg per side (to fill in the collector cells) - outer tanks refueled to full - inner tanks refueled up to total fuel equals 36500 kg - trim tank refueled up to 2400 kg - inner tank refueled to full - trim tank and center tanks are simultaneously refueled up to full. Inner qty = 25935 kg Outer qty = 2865 kg Trim qty = 2400 kg Total fuel qty = 60000 kg 130 Getting to Grips with Aircraft Weight and Balance C. BALANCE CHART DESIGN In the above example, FOB = 60000 kg. It leads to the following fuel tank distribution (when the fuel density is equal to 0.785 kg/l): Inner (one side) : 25935 kg Outer (one side) : 2865 kg corresponding to full outer (3650 liters) at the standard fuel density 0.785 kg/l Trim : 2400 kg As the automatic refueling sequence contains break points defined in volume (outer tanks are fueled to high level shut-off for instance), the corresponding fuel quantity in weight will depend on the fuel density. On the above example, if the density were 0.76 kg/l, then the outer weight would have been 2774 kg and so the inner weight would have been 26026 kg: Inner_weig ht = 60000 − (2774 × 2 + 2400) = 26026 kg per side 2 Consequently, the fuel weight distribution per tank depends on the fuel density. Getting to Grips with Aircraft Weight and Balance 131 WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN b) Determination of the fuel CG position per tank after the refueling process Once the fuel weight distribution per individual tank is known, the fuel CG per tank can be deduced thanks to individual fuel tank table published in WBM section 1.20.03. To do so, we need to convert the fuel weight in each tank in term of volume per tank. In fact, the fuel CG position per tank depends on the fuel volume in it. As a general fact, because to the fuel tanks shape the fuel CG in the tank depends on the actual fuel quantity in it. .That is why WBM individual fuel tank tables give the H-arm of the tank as a function of the fuel volume. • Ex : WBM A330-200 Table of Fuel H-ARM Outer tanks Outer fuel CG position is obtained Corresponding to 2865 kg at fuel density = 0.785 kg/l Back to the previous example, the outer fuel quantity (one side) was 2865 kg, i.e. 3650 l at 0.785 kg/l. The corresponding H-arm is therefore 38.579 m for both outer tanks (same quantity in both tanks). Using corresponding tables for inner and trim tanks, we can deduce: Inner: 25935 kg centered at 31.287 m Trim: 2400 kg centered at 59.096 m. Thanks to these individual fuel tank tables, we can now determine the total fuel CG position equal to the weighted average of the individual tank CG positions. Total fuel = 60000 kg Outer (one side) = 2865 kg centered at 38.579 m Inner (one side) = 25935 kg centered at 31.287 m Trim = 2400 kg centered at 59.096 m The total fuel CG position is: TotalFuelC G = 2 × 2865 × 38.579 + 2 × 25935 × 31.287 + 2400 × 59.096 = 33.096 m 60000 132 Getting to Grips with Aircraft Weight and Balance C. BALANCE CHART DESIGN c) Determination of the fuel vector after the refueling process The above process needs to be repeated for total fuel quantities from zero to full. In the Weight and Balance Manual the result is displayed in a graph with fuel quantity in liter on vertical axis and H-ARM in meter on horizontal axis : the fuel vector. It is important to note that this fuel vector depends on the fuel density. In fact, weight break points of the automatic refueling sequence lead to different volumes according to the fuel density and so, the shape of the fuel vector is impacted. In the WBM, the automatic refueling fuel vector is represented only at the standard fuel density: 0.785 kg/l. To obtain fuel vector at another fuel density, the whole above process has to be repeated for different values of automatic refueling sequence break points. • Ex : WBM A330-200 Automatic Refueling Fuel Vector at standard fuel density 0.785 kg/l 76433 liters (corresponding to 60000 kg at standard fuel density) 33.093 meters (corresponding to 60000 kg fuel CG position) Thanks to the fuel vector and for a given fuel density (here, 0.785 kg/l), for any fuel quantity, the corresponding fuel CG position can be easily found. As per previous example, for 60000 kg FOB (equivalent to 76433 liter at fuel density 0.785 kg/l) the corresponding fuel CG position is 33.093m (as computed above). Getting to Grips with Aircraft Weight and Balance 133 WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN d) Determination of the fuel vector expressed in ∆Index after the refueling process Now, for Balance Chart production purpose, we need to have this fuel vector expressed in ∆Index as a function of the fuel weight. This is realized converting the volume values into weight values and converting H-arm values into ∆Index. ∆Index fuel Weight = A new fuel vector is obtained giving for any fuel weight the impact in term of ∆Index. As for the WBM fuel vector (expressed in H-arm as a function of the fuel volume), this new fuel vector depends also on the fuel density. The below graph presents two fuel vectors for two different fuel densities: the standard one 0.785kg/l and a higher one 0.83 kg/l. The differences between the two fuel vectors are due to the definition of the break points of the automatic refueling sequence. Then, these differences are more important at break points where the involved tank(s) has (have) either a great capacity or a great lever arm compared to the lever arm reference. • WFuel × (H − arm fuel − HRef ) , C Ex : A330-200 Automatic Refueling Fuel Vector Weight 6 Fuel Vectors : 0.76 kg/l 0.785 kg/l 0.83 kg/l 5 3 4 2 1 Index From the above graph, it can be noted that the fuel density variation has a double effect on the fuel vector: 1. A vertical distortion (weight distortion) increasing with the fuel quantity and affecting points defined in volume (2, 5 and 6) 2. A horizontal distortion (index distortion) increasing with the tank H-arm compared to HRef and affecting point defined in weight (1, 3 and 4). 134 Getting to Grips with Aircraft Weight and Balance the method used to determine the aircraft CG may also add an inaccuracy source if it needs index rounding or index interpolation. pax.2. OPERATIONAL LIMITS DETERMINATION 3.1. it is impossible to check these CG positions against their corresponding CG limits. any additional item) − possible CG movements due to moving items during flight. the determination of the Landing CG and furthermore the In-flight CG positions on a paper document is much more difficult. Due to the CG position uncertainties some margins must be determined between the certified envelopes and the ones used on the trim sheet : the operational limits. In addition to these inaccuracy sources.2. CERTIFIED LIMITS Operational margin OPERATIONAL LIMITS On the balance chart the 3 operational limits – Takeoff. or on its location and/or CG position.1. An inaccuracy on the final CG value can be introduced because of a lack of precision either on item weight. Calculation principle The determination of the aircraft CG position using a paper or computerised trim sheet is affected by inaccuracy on the influence of item loading on the final aircraft CG position.…) Before flight the aircraft CG position must be checked against the three certified envelopes. BALANCE CHART DESIGN 3. TOW and CG position during flight one needs to know : − aircraft CG position and weight before loading any item − weight and position of each item loaded on the aircraft (cargo. Margins determination method 3. Method To determine the aircraft ZFW. The total possible inaccuracy made on CG estimation will result of a combination of all the individual errors : − due to initial conditions (aircraft DOW and DOCG) − due to cargo loading − due to passenger boarding − due to fuel loading. Landing and In-flight – are not represented because even if the Takeoff CG position check against its corresponding limit can be done after a manual or computerized computation. So on balance charts two operational limits are represented : − Operational Takeoff limit − Operational Zero Fuel limit The Zero Fuel limit is determined to ensure that during the whole flight and at landing the aircraft CG remains within the limits.C. fuel. Getting to Grips with Aircraft Weight and Balance 135 WEIGHT AND BALANCE ENGINEERING . 3. Furthermore the aircraft CG position changes during flight because of different items moving (landing gear. The inaccuracy shifting the CG forward reduces the aircraft total moment so this inaccuracy or movement results in a negative moment. O pe rational Limits 80000 Aircraft W eight (kg) 75000 70000 65000 60000 55000 50000 45000 40000 35000 20 Operational Margin Operational envelope C ertified envelope 70 INDEX The following paragraphs detail each error and CG movement evaluation. TOW and CG position computation is based on initial aircraft configuration corresponding to DOW and DOCG. This influence can be quantified as the difference between the trimming document final index and the index that would result of a calculation with no accuracy. If the CG shifts forward the CG H-arm decreases and so the resulting moment also decreases. Instead of using the index value the following method uses the moment and evaluate difference between the aircraft moment determined using the trimming document (assumed) and the real one. CG moves FWD moment < 0 CG moves AFT moment > 0 136 Getting to Grips with Aircraft Weight and Balance . Operational margins = (Real Aircraft Moment) – (Assumed Aircraft Moment) Note : inaccuracies and movements can shift the aircraft CG forward or aft.WEIGHT AND BALANCE ENGINEERING C. The method is to determine the influence that each lack of precision or each CG movement will have on the aircraft final CG position. Operational margins are the sum of the total possible inaccuracy and the possible aircraft CG movements due to : − landing gear movements − flaps/slats movements − water movements − movements in the cabin. this CG movement needs to be taken into account in the operational limits determination. BALANCE CHART DESIGN The aircraft ZFW. Due to some item movements during the flight the aircraft configuration may change. + E 2 n it is also said they are RANDOM or INDEPENDENT. Lets consider the total effect (E) is made of several individual effects E1.2.g... When the individual effects are SYSTEMATIC (if they occur surely at each flight) then they will CUMULATE and the total effect is. e. This occurs for the final calculation per flight phase. When effects are non-systematic..2.En. E = E1+E2+. Getting to Grips with Aircraft Weight and Balance 137 WEIGHT AND BALANCE ENGINEERING . they can compensate each other and the resulting error is always less important with independent effects than with systematic effects. E2.. Resulting moments determination After evaluating the individual moments corresponding to each lack of precision and/or to each movement it is necessary to determine their total effect in term of moment. E = E 21 + E 2 2 + ..+En it is also said they are NON RANDOM or DEPENDENT. The resulting cargo loading effect is the made of the effects due to the different cargo compartments. BALANCE CHART DESIGN 3. This total effect definition depends on the type of situation.C.. the two types of effects may be mixed. Note : Sometimes. When the individual effects are NON SYSTEMATIC (if they may occur or not at each flight) then they can COMPENSATE and the total effect is. its weight and CG position can be modified following maintenance tasks or cabin interior modifications.0210 m Then the aircraft weight and CG position can vary within the following values: DOWdocument .3. When defining the DOW and DOCG to be used in the loading and trimming documents the operator has two choices: 1. considering a group of aircraft as being part of one fleet so one single set of values (DOWfleet and DOCGfleet) is defined and used in the loading and trimming documents.WEIGHT AND BALANCE ENGINEERING C. considering each aircraft as independent so for each aircraft an individual set of values (DOW and DOCG) is set 2.5%MLW ≤ DOWaircraft ≤ DOWdocument + 0.5%Length of RC b) Inaccuracy on initial data In conclusion to the above statements.5%Length of RC Then during the aircraft life. As per aviation regulations a fleet of aircraft can be defined provided that. In that case the DOW and DOCG values used to enter the loading and trimming documents should be amended.5% of the aircraft Maximum Landing Weight A CG position maximum deviation of ± 0.1935m = ±0.5 % of 64 500 kg = ±322. for each aircraft of the fleet.021 m ≤ CG ≤ DOCGdocument + 0.5% of the Reference Chord length Note : in other words : an aircraft can be part of a fleet as long as DOWfleet – 0.5% of the Reference Chord length for the CG position. the DOW and DOCG assumed used in the loading and trimming documents is the aircraft one with a tolerable inaccuracy of ±0.021 m 138 Getting to Grips with Aircraft Weight and Balance . between two weighings. DOWaircraft and DOCGaircraft meet the allowed deviations to the fleet values : A DOW maximum deviation of ± 0.322 kg ≤ DOW ≤ DOWdocument + 322 kg DOCGdocument . Inaccuracy on initial data (DOW and DOCG) 3. As per aviation regulations the DOW document and DOCGdocument values amendment is mandatory as soon as DOWdocument – 0. paintings. DOW = 39 400 kg RC = 4.5%MLW for the weight and ±0.5%Length of RC ≤ DOCGaircraft ≤ DOCGfleet + 0. BALANCE CHART DESIGN 3. • Ex: A320 in the following configuration: MLW = 64 500 kg. Dry Operating Weight (DOW) definition : a) DOW and DOCG definition policy At delivery each aircraft is weighed to determine its Manufacturer’s Empty Weight (MEW) and the Corresponding CG position.1.3.5%MLW ≤ DOWaircraft ≤ DOWfleet + 0.5%MLW DOCGdocument – 0.5 kg The CG position allowance is ±0.0. Using these values the operator can determine the aircraft Dry Operating Weight (DOW) and the corresponding CG position of each aircraft.5 % of 4.5%Length of RC≤ DOCGaircraft ≤ DOCGdocument + 0.5%MLW DOCGfleet – 0.1935 m The weight allowance is ±0. 1935 = ±910m. Effect on the final aircraft CG position The inaccuracy on the aircraft initial CG position will generate an inaccuracy on the final CG position (ZFCG or TOCG) which can be determined in term of moment (EDOCG) EDOCG = Real Aircraft Moment – Assumed Aircraft Moment EDOCG = DOWreal x (H-armreal – H25) – DOWassumed x (H-armassumed – H25) In the following we consider that DOW real ≈ DOWassumed so EDOCG = DOWassumed x (H-armreal – H25) – DOWassumed x (H-armassumed – H25) EDOCG = DOWassumed x (H-armreal – H-armassumed) As per regulation (H-armreal – H-armassumed) cannot exceed ±0.5 × 4.1935 m EDOCG = (39400 + 4000 ) × 0.2. In order to avoid continuous balance documentation modification.5% of the Reference Chord length.5 × LengthRe ference Chord 100 Ex: A320 in the following configuration: MLW = 64 500 kg. EDOCG = (DOWassumed + m arg in ) × • ± 0.kg 100 Getting to Grips with Aircraft Weight and Balance 139 WEIGHT AND BALANCE ENGINEERING .5 × LengthRe ference Chord 100 Note : the effect value depends on the DOWassumed so each time the DOW has to be changed the effect needs to be recalculated and so the total effect on the aircraft CG determine shall be modified also. EDOCG = DOWassumed × ± 0. the operator can take a weight value of (DOWassumed + margin) including the possible weight modifications.3.C. DOW = 39 400 kg RC = 4. BALANCE CHART DESIGN 3. Inaccuracy on items loading on board the aircraft (passengers. cargo. The inaccuracy value depends on the relation between the position of the ∆WItem and the assumed position of the aircraft final CG − If the ∆WItem is forward of the assumed aircraft final CG then a positive weight inaccuracy +∆WItem will move the CG forward. Note : Effects are supposed to be independent : location is supposed to be accurately known to calculate the effect of the error in weight. fuel) Any item loaded onboard the aircraft has a given weight and location. and the weight is supposed to be accurately known to determine the effect of the error on location. this weight and/or CG position might not be known with enough precision. Note : the item weight is considered to be accurately known.WEIGHT AND BALANCE ENGINEERING C. Nevertheless. Eitem location = Real Aircraft Moment – Assumed Aircraft Moment Eitem location = (Aircraft Moment + Real Item Moment) – (Aircraft Moment + Assumed Item Moment) Eitem location = Real Item Moment – Assumed Item Moment Eitem location = Witem x (H-armitem real – H-armref) – Witem x (H-armitem assumed – H-armref) Eitem location = Witem x (H-armitem real – H-armitem assumed) Inaccuracy on the item weight Each item weight is known with a certain inaccuracy (∆WItem ) so for each item : Witem real = Witem assumed ± ∆WItem The inaccuracy on the item weight generates an inaccuracy on the final aircraft weight and CG position that can be determined in term of moment (Eitem weight). In the following paragraphs the method to determine the effect of each inaccuracy is developed. So there is an inaccuracy in the determination of the delta index due to the item loading which is due to an inaccuracy on either the item weight or on the item location. • Inaccuracy on the item location The inaccuracy on the item position generates an inaccuracy on the final aircraft CG position that can be determined in terms of moment (Eitem location). BALANCE CHART DESIGN 3. a negative weight inaccuracy ∆W Item will move the CG aft a/c CGW+∆WItem ∆ +∆WItem ∆ a/c W+∆WItem ∆ a/c CGassumed a/c Wassumed • 140 Getting to Grips with Aircraft Weight and Balance .4. Positive weight inaccuracy : +∆WItem a/c FWD CG limit a/c CGW+∆WItem ∆ a/c W+∆WItem ∆ a/c CGassumed a/c Wassumed a/c AFT CG limit a/c FWD CG limit a/c CGW+∆WItem ∆ a/c W+∆WItem ∆ a/c CGassumed a/c Wassumed a/c AFT CG limit ∆WItem located in front of a/c CGassumed ∆WItem located in front of a/c CGassumed non critical situation Negative weight inaccuracy : -∆WItem a/c FWD CG limit a/c CGassumed a/c Wassumed a/c CGW-∆WItem ∆ a/c W-∆WItem ∆ a/c AFT a/c FWD CG limit CG limit critical situation a/c CGassumed a/c Wassumed a/c AFT CG limit a/c CGW-∆WItem ∆ a/c W-∆WItem ∆ ∆WItem located in front of a/c CGassumed ∆WItem located in front of a/c CGassumed non critical situation critical situation Getting to Grips with Aircraft Weight and Balance 141 WEIGHT AND BALANCE ENGINEERING . BALANCE CHART DESIGN − If the ∆WItem is aft of the assumed aircraft final CG then a positive weight inaccuracy +∆WItem will move the CG aft. because the weight inaccuracy may lead to a real CG out of the limits.C. The ∆WItem impact is critical when the aircraft assumed CG is close to the limits. a negative weight inaccuracy -∆WItem will move the CG forward a/c CGW-∆WItem ∆ a/c W-∆WItem ∆ a/c CGassumed a/c Wassumed -∆WItem ∆ Note : the item position is considered to be accurately known. • Eg : impact of ∆WItem if ∆WItem is located in front of CGassumed. on the limit. a/c CGlimit a/c CGW+∆WItem ∆ a/c W+∆WItem ∆ a/c W+∆WItem ∆ a/c CGassumed a/c Wassumed Eitem weight Eitem weight is maximum when a/c CGassumed is on the aircraft CG limit. Eitem weight = (Momentaircraft assumed +Moment∆Witem) – Momentaircraft on the limit Eitem weight = [Waircraft x (H-armaircraft .(W ± ∆WItem) x (H-armaircraft – H-armRef) Eitem weight = ± ∆WItem x (H-arm∆Witem . 142 Getting to Grips with Aircraft Weight and Balance . BALANCE CHART DESIGN The impact in term of moment (Eitem weight) of this inaccuracy is determined by the difference between the aircraft real moment at aircraft weight : W item assumed ± ∆W Item and the aircraft moment if the aircraft CG remains in the limit at aircraft weight : W item assumed ± ∆W Item. in other words in the case when with the inaccuracy in weight the aircraft CG remains at the same position.H-armRef) ± ∆WItem x (H-arm∆Witem .WEIGHT AND BALANCE ENGINEERING C. a/c CGlimit a/c CGW+∆WItem ∆ a/c W+∆WItem ∆ a/c W+∆WItem ∆ a/c CGassumed a/c Wassumed Eitem weight So Eitem weight is determined by the difference between the moment of the aircraft ± ∆WItem on board and the moment of the aircraft at (W aircraft assumed ± ∆W Item) in case ± ∆WItem has no impact on the aircraft CG.H-armRef)] .H-armaircraft) With H-armaircraft = H-armlimit Eitem weight = ± ∆WItem x (H-arm∆Witem .H-armlimit) Determining the Eitem weight value consists of checking the different possible H-armlimit to determine the more limiting Eitem weight. pallets96” and/or Bulk) − For each configuration the forward inaccuracy is determined when all the positions in front of the average H-arm are full and all the positions aft of the average H-arm are empty. This difference will generate an inaccuracy on the aircraft CG determination. this delta index is based on an average H-arm for the corresponding compartment. This inaccuracy is named cargo CG tolerance inaccuracy. each cargo position CG is known with a certain inaccuracy. − Study each configuration separately (containers. Eitem location is determined with H-armitem assumed being H-armCargoX and H-armitem real being the H-arm of the studied configuration. Now the real loading may have an average H-arm different from the average one.C. when determining the average cargo compartment H-arm. on the balance chart the cargo influence is taken into account as a delta index per cargo compartment (CARGO 1. two sources of inaccuracies have to be considered. in this case the cargo distribution inaccuracy is nil. − Determine the configuration generating the highest inaccuracy. this inaccuracy will generate an inaccuracy on the aircraft CG determination.1. − For each configuration the aft inaccuracy is determined when all the positions aft of the average H-arm are full and all the positions in front of the average H-arm are empty. This inaccuracy needs to be determined for each cargo compartment that is represented on the balance chart. then the cargo delta index may be determined for each individual cargo position. − On the other hand. Then the total inaccuracy is determined considering each cargo compartment inaccuracy independent from the other ones. pallets 88”. BALANCE CHART DESIGN 3. Getting to Grips with Aircraft Weight and Balance 143 WEIGHT AND BALANCE ENGINEERING . E cargo distibution fwd = − E 2 cargo1 fwd + E 2 cargo2 fwd + E 2 cargo3 fwd + E 2 cargo4 fwd + E 2 cargo5 fwd E cargo distibution aft = + E 2 cargo1 aft + E 2 cargo2 aft + E 2 cargo3 aft + E 2 cargo4 aft + E 2 cargo5 aft Note : when an EDP system is used to compute the aircraft CG position and weight. • Cargo distribution inaccuracy: Eitem location = Witem x (H-armitem real – H-armitem assumed) For this inaccuracy determination the different loading scenarios have to be studied. This inaccuracy is named cargo distribution inaccuracy.4. CARGO2…).5 ∆Index for cargo loading. Inaccuracy on cargo loading on board the aircraft a) Inaccuracy on the cargo location For cargo loading. − On the one hand. The process for checking the different configuration is the following : − Determine the cargo compartment average H-arm : refer to paragraph 2. For each of them. 5 ∆Index for cargo loading .H − armPosition11+position12 = 11 W11 + W12 and Wposition11+position12 = Wposition11 + Wposition12 Aft inaccuracy CARGO 1 H-arm position 11 11 H11 W11 12 H12 W12 13 H13 W13 14 H14 W14 15 H15 W15 H-arm cargo 1 H-arm real loading : position13+position14+position15 Eitem location = Witem x (H-armitem real – H-armitem assumed) ECargo1 distribution aft = Wposition13+position14+position15 x (H-arm position13+position14+position15 – H-armcargo1) According to 2.H − arm cargo1 = W11 × H11 + W12 × H12 + W13 × H13 + W14 × H14 + W15 × H15 W11 + W12 + W13 + W14 + W15 W × H11 + W12 × H12 . BALANCE CHART DESIGN • Example Cargo 1 inaccuracy for configuration with 5 ULDs : Forward inaccuracy CARGO 1 H-arm position 11 11 H11 W11 12 H12 W12 13 H13 W13 14 H14 W14 15 H15 W15 H-arm real loading : position11+position12 H-arm cargo 1 Eitem location = Witem x (H-armitem real – H-armitem assumed) ECargo1 distribution fwd = Wposition11+position12 x (H-arm position11+position12 – H-armcargo1) According to 2.5 ∆Index for cargo loading W11 × H11 + W12 × H12 + W13 × H13 + W14 × H14 + W15 × H15 W11 + W12 + W13 + W14 + W15 W × H13 + W14 × H14 + W15 × H15 .WEIGHT AND BALANCE ENGINEERING C.H − arm cargo1 = and Wposition13+position14+position15 = Wposition13 + Wposition14+ Wposition15 144 Getting to Grips with Aircraft Weight and Balance .H − armPosition13 +position14 +position15 = 13 W13 + W14 + W15 . 260 – 12.971 × 1132 = 14.426 m FORWARD INACCURACY: Position 11 is the only position in front of the average H-arm.m) (W x H) 11227.260 m = W12 + W13 1045 + 1132 ECargo1 distribution aft = 2357 x (14.C.1 3402 H-armcargo1 = 12.2 42273.426) = – 1757.426) = + 4322.7 kg.m AFT INACCURACY: Position 12 and 13 are aft of the average H-arm. Determination of the average H-arm of the compartment 1: Position Maximum allowable H-arm (Bulk) Weight (kg) (m) 11 1045 10. ECargo1 distribution fwd = W11 x (H11 – Hcargo1) ECargo1 distribution fwd = 1045 x (10.5 15230.433 13 1132 13.744 – 12.971 ∑= MOMENT (kg.744 12 1225 12.7 kg. BALANCE CHART DESIGN • Ex: A320 bulk loading in the compartment 1.433 × 1045 + 13.m Getting to Grips with Aircraft Weight and Balance 145 WEIGHT AND BALANCE ENGINEERING . ECargo1 distribution aft = W12+13 x (H12+13 – Hcargo1) W12+13 = W12 + W13 = 1225 + 1132 = 2357 kg H12+13 = H12 × W12 + H13 × W13 12.4 15815. 801 × 3174 H12 +13 = 12 = = 18 m W12 + W13 3174 + 3174 ECargo1 distribution aft = 6348 x (18.m Pallet 88” configuration Position 12P is the only position in front of the average H-arm.m Note: In this particular case (A330) the scenario with the highest inaccuracy corresponds to the heaviest pallets configuration.885 12 or 12P 17. ECargo1 distribution fwd = W11 x (H11 – Hcargo1) ECargo1 distribution fwd = 3174 x (15. The following table gives the H-arm for each ULD position on the compartment 1.128) = – 6343 kg.218 × 3174 + 18. ECargo1 distribution fwd = 5103 x (15. LD1 and LD6) and pallets PKx have the same lever arm.738 – 17. ECargo1 distribution fwd = 4626 x (15.450 – 17.450 18.801 Maximum allowable weight (kg) per 3174 4626 5103 ULD The average center of gravity position of this compartment is 17.128) = – 6222 kg. one allowing the highest loaded weight. in this example LD6.0095 – 17. H-arm (m) Container (LD6) POSITION Pallet 88" Pallet 96" 11 or 11P 15. It can be loaded with: Either 6 containers LD3 (AKE) or 3 containers LD1 (AKC) or 3containers LD6 (ALF) Or 3 pallets 60.m The highest inaccuracy is obtained for Pallet 96” configuration. 13).4 x 125 in (PKx) or 2 pallets 88 x 125 in (PAx) or 2 pallets 96 x 125 in (PMx) Containers (LD3. 146 Getting to Grips with Aircraft Weight and Balance . 12.m Pallet 88” configuration Position 11P is the only position in front of the average H-arm.128) = + 6115 kg.m Pallet 96” configuration Position 12P is the only position in front of the average H-arm.m The highest inaccuracy is obtained for Pallet 96” configuration. ECargo1 distribution aft = 4626 x (18.432 15.128 meters Hcargo1 = 17.348 13 18. So.885 – 17.128) = + 6225 kg.432 – 17.738 15.m AFT INACCURACY: LD6 configuration Position 12 and 13 are aft of the average H-arm. nevertheless it is not always the case and all scenarios need to be checked for each individual computation. this value is retained as ECargo1 distribution fwd = – 6343 kg. The compartment 1 of the A330-300 has 3 individual positions (11. this value is retained as ECargo1 distribution aft = + 6225 kg. ECargo1 distribution aft = 5103 x (18.m Pallet 96” configuration Position 11P is the only position in front of the average H-arm.128) = + 5595 kg.218 18.128) = – 5383 kg.WEIGHT AND BALANCE ENGINEERING C.348 – 17.128 m. we will just use one of those ULDs. ECargo1 distribution aft = W12+13 x (H12+13 – Hcargo1) W12+13 = W12 + W13 = 2 x 3174 = 6348 kg H × W12 + H13 × W13 17. BALANCE CHART DESIGN • Ex: A330-200 containerized loading in the compartment 1. FORWARD INACCURACY: LD6 configuration Position 11 is the only position in front of the average H-arm. For each ULD baseplate the CG is never right on the baseplate geometric center. The longitudinal allowance is equal to ±10% of the depth of the bulk position. The process for checking the different configuration is the following : − Study each configuration separately (containers.. Eitem location is determined with (H-armitem real – H-armitem assumed) being the allowed tolerance when loading a cargo position. For each of them.C. E = E 21 + E 2 2 + . Eitem CG tolerance = Witem x tolerance This tolerance is described in the WBM for ULD loaded aircraft in section 1.. pallets 88”. BALANCE CHART DESIGN • Cargo CG tolerance inaccuracy: Eitem location = Witem x (H-armitem real – H-armitem assumed) For this inaccuracy determination the different loading scenarios have to be studied. bulk loaded aircraft the same principle is considered. The longitudinal allowance is equal to ±10% of the depth of the baseplate. For. + E 2 n − Determine the configuration generating the highest inaccuracy. Getting to Grips with Aircraft Weight and Balance 147 WEIGHT AND BALANCE ENGINEERING .10. pallets96” and/or Bulk) − For each configuration determine the total inaccuracy considering that the inaccuracy for each ULD/bulk position is independent from the other ones. LD6) ± 0.m 2 E LD6 configuration CG tolerance = ± E LD6 CG tolerance × 3 = ±485.m 2 E LD1 configuration CG tolerance = ± E LD1 CG tolerance × 3 = ±242. BALANCE CHART DESIGN • Ex: A330-200 containerized loading in the compartment 1.9 × 2 = ±1462.6 in) The maximum allowable weight (kg) per ULD is Container (LD3.WEIGHT AND BALANCE ENGINEERING C. 13).8 × 3 = ±420.153 m (± 6.153 = ± 242.244 m (± 9.9 kg.m The highest inaccuracy is obtained for Pallet 96” configuration.m Note: In this particular case (A330) the scenario with the highest inaccuracy corresponds to the heaviest pallets configuration. LD1.m LD6 configuration 3 LD6 can be loaded Eitem CG tolerance = Witem x tolerance ELD6 CG tolerance = 3174 x ± 0. 148 Getting to Grips with Aircraft Weight and Balance .244 = ± 1245.6 × 3 = ±841.04 in) Pallet 88" (PAx: 88 x 125 in) ± 0.1 kg.m Pallet 88” configuration 2 pallets can be loaded Eitem CG tolerance = Witem x tolerance EPallet 88” CG tolerance = 4626 x ± 0. this value is retained as ECargo1 CG tolerance = ± 1760. The compartment 1 of the A330-300 has 3 individual positions (11.2235 = ± 1033.m 2 E Pallet 88"configuration CG tolerance = ± E Pallet88" CG tolerance × 2 = ±1033.1 kg.2 kg.6 kg.m 2 E LD3 configuration CG tolerance = ± E LD3 CG tolerance × 6 = ±242.153 = ± 242.4 x 125 in (PKx) or 2 pallets 88 x 125 in (PAx) or 2 pallets 96 x 125 in (PMx) The longitudinal allowance for each type of ULD is : Container (LD3.1 × 2 = ±1760.m LD1 configuration 3 LD1 can be loaded Eitem CG tolerance = Witem x tolerance ELD1 CG tolerance = 1587 x ± 0.8 kg.153 = ± 485.m Pallet 96” configuration 2 pallets can be loaded Eitem CG tolerance = Witem x tolerance EPallet 96” CG tolerance = 5103 x ± 0.8 in) Pallet 96" (PMx: 96 x 125 in) ± 0. nevertheless it is not always the case and all scenarios need to be check for each individual computation. 12.9 kg.8 kg.2235 m (± 8. It can be loaded with: Either 6 containers LD3 (AKE) or 3 containers LD1 (AKC) or 3 containers LD6 (ALF) Or 3 pallets 60.m 2 E Pallet96" configuration CG tolerance = ± E Pallet 96" CG tolerance × 2 = ±1245.9 kg.5 kg. LD1) 1587 kg Container (LD6) 3174 kg Pallet 88" (PAx: 88 x 125 in) 4626 kg Pallet 96" (PMx: 96 x 125 in) 5103 kg LD3 configuration 6 LD3 can be loaded Eitem CG tolerance = Witem x tolerance ELD3 CG tolerance = 1587 x ± 0.8 × 6 = ±594.8 kg. So Ecargo weight is usually supposed to be nil. this inaccuracy may be due to the fact that the ULD weight is estimated and not weighed or to the fact that the baggage weight per cargo position is estimated. In the case a cargo weight inaccuracy is to be determined the method to be applied is similar to the one described in the next chapter for passenger weight inaccuracy. The process for checking the different configuration is the following : − Determine the cabin section average H-arm : refer to paragraph 2. then for baggage the total weight of baggage per flight is accurately known as each individual piece of luggage is weighed. This difference will generate an inaccuracy on the aircraft CG determination. But this boarding configuration is not a realistic one and the inaccuracy is in this case very high. Now the real loading may result in an H-arm different from the average one. CABIN OB.2. usually using an average weight per baggage piece. This inaccuracy is named passenger distribution inaccuracy. 3. So a realistic boarding scenario needs to be determined. − Determine the passenger seating configuration which generates a significant inaccuracy.4 ∆Index for passenger boarding. H-arm real passenger seating configurations H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC Getting to Grips with Aircraft Weight and Balance 149 WEIGHT AND BALANCE ENGINEERING . Inaccuracy on passenger loading on board the aircraft a) Inaccuracy on the passengers’ location On the balance chart the passenger influence is taken into account as a delta index per passenger cabin section (CABIN OA. this delta index is based on an average Harm for the corresponding cabin section.4. BALANCE CHART DESIGN b) Inaccuracy on the cargo weight Cargo weight is supposed to be known without inaccuracy : for freight loading airlines usually weight the pallets and container after they are prepared. • Passenger distribution inaccuracy: Eitem location = Witem x (H-armitem real – H-armitem assumed) Eitem location is determined with H-armitem assumed being H-armCabinOX and H-armitem real being the H-arm of the real passengers seating configuration. Note : in case the cargo weight cannot be accurately known it may be needed to introduce a cargo weight inaccuracy.C. The maximum inaccuracy would be determined when all seats in front of the average H-arm are full and all seats aft of the average H-arm are empty. …). WEIGHT AND BALANCE ENGINEERING C. H-arm real passenger seating configurations H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC − Or all window and aisle seats are full and all the center seats in front of the average H-arm are full and all the center seats aft of the average H-arm are empty. H-arm real passenger seating configurations H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC The aft inaccuracy is computed following the same passenger seating configuration but with passengers first seated in the rear part of the cabin section. 150 Getting to Grips with Aircraft Weight and Balance . Following this scenario the forward inaccuracy is determined when − Either all the window seats in front of the average H-arm are full and all the window seats aft of the average H-arm are empty. Note : on the majority of cabin layouts the second option generates the highest significant inaccuracy. − Passengers board then on aisle seats − Finally passengers board on middle seats. H-arm real passenger seating configurations H-arm Cabin OA H-arm Cabin OB H-arm Cabin OC − Or all window seats are full and all the aisle seats in front of the average H-arm are full and all the aisle seats aft of the average H-arm are empty. BALANCE CHART DESIGN The following boarding scenario is taken into account : − Passengers board first on (or ask first for) window seats. C. E passenger distibution aft = + E 2 Cabin OA aft + E 2 Cabin OB aft + E 2 Cabin OC aft + .191 18.752 15. • Ex : A320 forward inaccuracy with the following cabin layout ROW H.965 14.177 13.327 17.078 29. It is worth taking in account additional margins for those specific cases.842 19. Epassenger distibution fwd = − E 2 Cabin OA fwd + E 2 Cabin OB fwd + E 2 Cabin OC fwd + . Note : when applying the realistic boarding scenario.405 12.390 13.. BALANCE CHART DESIGN The passenger distribution inaccuracy is determined for each cabin section that is represented on the balance chart. Then the total inaccuracy is determined considering each cabin section inaccuracy independent from the other ones.991 22. for example if one emergency exit is inoperative..44 m HOB=16. These margins are computed for each specific cabin layout and unoccupied seats configurations.ARM (m) 9.416 21..928 26.39 m HOC=25. In some case airlines may decide that some seats must remain unoccupied.4 ∆Index for passenger boarding determine. in this case the passenger distribution inaccuracy is nil. Note : when an EDP system is used to compute the aircraft CG position and weight.53 m FORWARD INACCURACY Considering the following loading scenario Getting to Grips with Aircraft Weight and Balance 151 WEIGHT AND BALANCE ENGINEERING . HOA=10.141 25.475 10. then the passenger delta index may be determined for each individual passenger seat row.540 16. it is considered that all the passenger seats are available.ARM (m) 20..629 LHPAX 2 2 2 3 3 3 3 3 3 3 3 3 3 RHPAX 2 2 2 3 3 3 3 3 3 3 3 3 3 ROW 15 16 17 18 19 20 21 22 23 24 25 26 27 OA OB 01 02 03 04 05 06 07 08 09 10 11 12 14 OC H.054 18.204 21.865 LHPAX 3 3 3 3 3 3 3 3 3 3 3 3 3 RHPAX 3 3 3 3 3 3 3 3 3 3 3 3 3 OA OB OC Referring to 2.290 29.353 25.566 24. In these specific cases passenger boarding may generate a higher inaccuracy than the one taken into account in the operational margin determination.779 23.440 11.503 28.716 27. 2 – 10.475 × 4 × 84 + 10.53) = – 3568.44) = – 161.2m = 8 × 84 Inaccuracy for cabin OB Ecabin OB distribution fwd = Wpax in cabin OB fwd x (H-armpax in cabin OB fwd – H-armOB) Wpax in cabin OB fwd = 34 x Pax average weight = 34 x 84 = 2856 kg H-armpax in cabin OB fwd = 15.12 kg. m 152 Getting to Grips with Aircraft Weight and Balance .35 m Ecabin OC distribution fwd = 3024 x (24.WEIGHT AND BALANCE ENGINEERING C.m Hrow1 × 4 × Pax average weight + Hrow2 × 2 × Pax average weight + Hrow3 × 2 × Pax average weight 8 × Pax average weight 9.35 – 25.12² + 3568.64kg. BALANCE CHART DESIGN Inaccuracy for cabin OA Ecabin OA distribution fwd = Wpax in cabin OA fwd x (H-armpax in cabin OA fwd– H-armOA) Wpax in cabin OA fwd = 8 x Pax average weight = 8 x 84 = 672 kg H .armpax in cabin OA fwd = H .28 kg.37 – 16.37 m Ecabin OB distribution fwd = 2856 x (15.23² + 2931.arm pax in cabin OA fwd Ecabin OA distribution fwd = 672 x (10.32² = −4620.m Inaccuracy for cabin OC Ecabin OC distribution fwd = Wpax in cabin OC fwd x (H-armpax in cabin OC fwd– H-armOC) Wpax in cabin OC fwd = 36 x Pax average weight = 36 x 84 = 3024 kg H-armpax in cabin OC fwd = 24.405 × 2 × 84 = 10.32 kg.m Total inaccuracy for all the cabins E passenger distibution fwd = − 161.39) = – 2913.44 × 2 × 84 + 11. For each cabin section used on the balance chart we have Wpax real OX = Wpax average OX ± ∆Wpax OX Wpax real OX = Wpax average x (number of pax in OX) ± ∆Wpax OX ∆Wpax OX is determined considering that each individual passenger weight inaccuracy is independent from the weight inaccuracy of the other passengers. the 3σ value is chosen to ensure that Wpax average covers 99. E passenger weight fwd = − E 2 Cabin OA fwd + E 2 Cabin OB fwd + E 2 Cabin OC fwd + . • Passenger weight inaccuracy The real passenger weight is W pax real = Wpax average ± ∆Wpax Wpax average and ∆W pax are determined in relation with the statistical survey used to determine the passenger weight.H-armlimit) The passenger weight inaccuracy is determined for each cabin section that is represented on the balance chart. This difference will generate an inaccuracy on the aircraft CG determination. E passenger weight aft = + E 2 Cabin OA aft + E 2 Cabin OB aft + E 2 Cabin OC aft + .C. this delta index is based on an average passenger weight for the corresponding cabin section.. Now the real loading may have a total weight different from the one determined using average weight.. This inaccuracy is named passenger weight inaccuracy. EcabinXX weight = ± ∆Wpassengers in cabin XX x (H-armcabin XX .73 % of the population.H-armlimit) The inaccuracy in weight is maximum when the cabin section is full of passengers so ∆Wpassengers in cabin XX = 3σ maximum number of passengers in sectionXX Then the total inaccuracy is determined considering each cabin section inaccuracy independent from the other ones.. ∆Wn pax = ∆Wpax1 + ∆Wpax2 + . Getting to Grips with Aircraft Weight and Balance 153 WEIGHT AND BALANCE ENGINEERING . Nb of pax Standard Deviation σ Pax average Weight µ Pax weight Wpax average = µ and ∆Wpax = 3σ.. BALANCE CHART DESIGN b) Inaccuracy on the passengers’ weight On the balance chart the passenger influence is taken into account as a delta index per passenger cabin section (CABIN OA. ∆Wnpax = n × (3σ )2 = 3σ n • Impact of pax weight inaccuracy on aircraft CG determination Epassenger weight = ± ∆Wpassenger x (H-arm∆Wpassenger . …).. CABIN OB. + ∆Wpaxn 2 2 2 The inaccuracy is the same for each individual passenger and equals 3σ.. The forward limit CG of the A320 is between 15% (18.53 − 18.39 m for 66 passengers HOC=25.44 − 18.53 m is aft for the limit so a negative ∆Wpassengers in cabin OC may cause the CG move out of the limit. The more conservative EcabinOA weight is obtained for H-armlimit = 18.51 m E cabinOC weight = 3 × 15 66 × (16.51 m) for aircraft weight between minimum weight and 73 500 kg. BALANCE CHART DESIGN • Ex : A320 forward inaccuracy with the above example cabin layout Referring to 2.4 ∆Index for passenger boarding determine.43 m E cabinOA weight = . The more conservative EcabinOB weight is obtained for H-armlimit = 18.H-armlimit) HOC=25.44 m is forward for the limit so a positive ∆Wpassengers in cabin OA may cause the CG move out of the limit.43) = −2711kg.H-armlimit) HOA=10.43 m) and 17% (18.m Total inaccuracy for all the cabins E passenge weight fwd = − 1258² + 755² + 2711² = −3082kg. The more conservative EcabinOC weight is obtained for H-armlimit = 18.51) = −755kg. HOA=10.H-armlimit) HOB=16.44 m for 12 passengers HOB=16.WEIGHT AND BALANCE ENGINEERING C.m Cabin OC : EcabinOC weight = ± ∆Wpassengers in cabin OC x (H-armcabin OC .39 m is forward for the limit so a positive ∆Wpassengers in cabin OB may cause the CG move out of the limit.m 154 Getting to Grips with Aircraft Weight and Balance .51 m E cabinOA weight = 3 × 15 12 × (10.51) = −1258kg.53 m for 72 passengers Passenger average weight = 84 kg and corresponding standard deviation = 15 kg. Cabin OA : EcabinOA weight = ± ∆Wpassengers in cabin OA x (H-armcabin OA .3 × 15 72 × (25.39 − 18.m Cabin OB : EcabinOB weight = ± ∆Wpassengers in cabin OB x (H-armcabin OB . this delta index is based on a fuel H-arm for the corresponding fuel weight. Now the fuel H-arm depends on the fuel volume contained in each tank and this volume is linked to the fuel weight through the fuel density. This Zero Fuel limit is used to ensure that flight CG all along the flight and landing CG before landing are within their own operational limits.4.83 kg/l. consequently the fuel density variation does not lead to huge fuel quantity variation.3. furthermore the fuel tanks position is close to the Reference Chord.76 kg/l and 0. • Ex : A320-200 70 65 WEIGHT (5 ton step) Max aft error Difference between 0.C. Fuel index table can be available for one single fuel density (usually for single aisle aircraft) or for a discrete range of fuel densities (for aircraft equipped with a trim tank). This inaccuracy is named fuel density inaccuracy. In addition the Zero Fuel limit design is based on the theoretical fuel vector at a chosen density (usually 0. As a standard density value is used for the Zero Fuel limit determination it is necessary to take into account the possible differences on actual aircraft CG due to density impact.785 kg/l 0.76 and 0. On single aisle aircraft (A318/A319/A320/A321.785 kg/l).83 kg/l Max fwd error 40 INDEX 50 60 70 Getting to Grips with Aircraft Weight and Balance 155 WEIGHT AND BALANCE ENGINEERING .785 kg/l).76 kg/l 0. the maximum forward and aft ∆index between the reference fuel index table and the fuel index values determined at extreme fuel densities must be included into the fuel allowance. So an inaccuracy on fuel density will generate an inaccuracy on the fuel H-arm and consequently on the aircraft CG determination. in this document the word density will be used. As the fuel density can be assumed to vary between 0. • Fuel density inaccuracy 1. Inaccuracy on the fuel ∆index determination. That is why fuel index table is established at a single reference density (usually 0. Note : Fuel density is also called fuel specific gravity. total fuel quantity is around 20 tons. A319 corporate jet excluded). Inaccuracy on fuel loading on board the aircraft a) Inaccuracy on the fuel location On the balance chart the fuel influence is taken into account as a delta index per total fuel quantity. BALANCE CHART DESIGN 3.785 kg/l fuel vectors is negligible 60 55 50 45 40 35 30 0. +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –8 –10 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –7 … +3 +2 +1 +0 –1 –2 –3 –4 –4 –5 –6 –8 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –5 –7 … +3 +2 +1 +0 –1 –2 –3 –3 –4 –5 –6 –8 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –3 –5 –7 … +3 +2 +1 +0 –1 –2 –2 –3 –4 –5 –6 –7 –9 –10 –10 –2 –4 –6 –8 –8 –4 +1 +3 +1 –1 –3 –5 –7 … +3 +2 +1 +0 –1 –1 –2 –3 –4 –5 –6 –7 –8 –10 –10 –2 –4 –6 –8 –8 –4 +1 +3 +1 –1 –3 –5 –7 … +4 +3 +2 +1 +0 +0 –1 –2 –3 –4 –5 –6 –7 –8 –10 –10 –2 –4 –6 –8 –8 –4 +1 +3 +1 –1 –3 –5 –7 … +3 +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –8 –9 –11 –10 WEIGHT DENSITY (kg/l) (kg) 0.795 0. Actual density of the day can be an intermediate density and an interpolation will be required to get the fuel ∆index. Inaccuracy on the Zero fuel limit design The Zero Fuel limit design process (see related chapter “Zero fuel limit determination”) uses a reference fuel vector that is leaned on operational flight and landing operational limits. a fuel density variation can imply a significant ∆index variation for a given weight value.. flight and landing operational allowances have to include an additional margin covering the zero fuel limit design. +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. • 000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 26000 .810 0.785 0.825 0. As actual fuel vector may be different from the reference one (due to a different fuel density). half of the maximum forward and aft index variation between two consecutive fuel densities has to be included into the fuel allowance. Consequently.. +2 +1 +0 +0 –1 –2 –3 –4 –5 –6 –8 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. +2 +1 +0 –1 –2 –2 –3 –4 –6 –7 –2 –4 –6 –8 –8 –4 +1 +1 –1 –2 –4 –6 –8 … +2 +1 +0 –1 –1 –2 –3 –4 –5 –7 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 …. wide-body aircraft (A300/A310) and single aisle aircraft equipped with ACTs the total fuel quantity reaches higher values and the fuel tanks may far from the Reference Chord (specially Trim Tank and ACTs).765 0. 2. +2 +1 +0 –1 –2 –2 –3 –4 –6 –8 –2 –4 –6 –8 –8 –4 +1 +1 –1 –3 –4 –6 –8 …. fuel index tables are usually established for a discrete range of fuel densities. a 0. To do so.800 0. BALANCE CHART DESIGN On long range aircraft (A330/A340). +2 +1 +1 +0 –1 –2 –3 –4 –5 –6 –8 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 ….790 0. maximum forward and aft index variation at critical points (because they are the points used in the zero fuel limit design) between the reference fuel vector and the extreme fuel vectors have to be included into the fuel allowance. 87000 89000 91000 93000 95000 97000 99000 101000 103000 105000 107000 109000 111000 113000 115000 FULL –9 –9 –9 –9 –9 –9 –9 –9 –9 –10 –10 Ex : A330-200 –2 –4 –6 –8 –8 –4 +1 +1 –1 –3 –5 –6 –8 ….WEIGHT AND BALANCE ENGINEERING C. That is why.770 0.760 0.u Consequently.830 Maximum fwd and aft index difference between two consecutives fuel densities: 1 i.820 0. +3 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –8 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –7 ….780 0.815 0. +2 +2 +1 +0 –1 –2 –3 –4 –5 –6 –7 –9 –2 –4 –6 –8 –8 –4 +1 +2 +0 –2 –4 –6 –8 ….5 i. To cover interpolation potential error.775 0. 156 Getting to Grips with Aircraft Weight and Balance .u fwd and aft margin will be included into the fuel allowance. to cover interpolation.805 0. This inaccuracy is named fuel weight inaccuracy. indeed throughout the whole fuel vector the aircraft CG must remain in the limits. This difference between estimated and real fuel weight per tank will generate an inaccuracy on the aircraft CG determination. Critical points are defined phase per phase.C. This inaccuracy is linked to the Fuel Quantity Indicator (FQI) system inaccuracy whatever the flight phase an inaccuracy needs to be taken into account. ∆Wfuel tank n = ±1% Total_weighttank n ± 1% Actual_weighttank n Note : if one tank is empty the ∆Wfuel tank is considered nil. For each tank the fuel quantity is known with a certain accuracy. Fuel weight inaccuracy The real fuel weight is W fuel real = Wfuel estimated ± ∆Wfuel For each tank. Note : These figures are conservative ones (refer to Aircraft Maintenance Manual section 28-4200). Some points are more critical than others: those points corresponding to a fuel quantity for which ± ∆Wfuel may cause the aircraft CG be shifted out of the certified limits. some points of the vector being shifted forward or aft. one being critical for the forward certified limit and another for the aft certified limit. There are called critical points. • Each tank quantity is independent from the other tanks’ one. BALANCE CHART DESIGN b) Inaccuracy on the fuel weight On the balance chart the fuel influence is taken into account as a delta index per total fuel quantity which is the sum of the delta indexes per individual tanks. Getting to Grips with Aircraft Weight and Balance 157 WEIGHT AND BALANCE ENGINEERING . They are determined leaning the fuel vector on the aircraft certified limits. plus ±1% of the actual fuel quantity in the tank. Such a weight deviation per tank has an impact on the actual fuel vector shape. the inaccuracy is ±1% of the tank capacity. Forward critical point: The forward critical point for the takeoff phase is defined as the contact point between fuel vector and forward takeoff certified limit corresponding to the highest fuel quantity. the whole fuel vector between the critical point and fuel = 0 kg remaining inside flight and landing limits.WEIGHT AND BALANCE ENGINEERING C. 158 Getting to Grips with Aircraft Weight and Balance . BALANCE CHART DESIGN • Ex: A330-200 aircraft with FCMC stage 9. WEIGHT 240000 230000 220000 210000 200000 190000 180000 170000 160000 Forward Takeoff critical point 36 500 kg 150000 140000 130000 Takeoff Flight Landing 120000 110000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 INDEX 190 .Aft critical point: WEIGHT 240000 230000 220000 210000 200000 190000 180000 170000 Aft Takeoff critical point 42 900 kg 160000 150000 140000 130000 Takeoff Flight Landing 120000 110000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 INDEX 190 The aft critical point for the takeoff phase is defined as the forward one but with respect to the aft takeoff envelope.0 Takeoff phase . WEIGHT 240000 230000 220000 Aft Flight critical point 38 900 kg 210000 200000 190000 180000 170000 160000 150000 140000 130000 Takeoff Flight Landing 120000 110000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 INDEX 190 Getting to Grips with Aircraft Weight and Balance 159 WEIGHT AND BALANCE ENGINEERING .C.Forward critical point: The forward critical point for the flight phase is defined as the contact point between fuel vector and forward flight certified limit. WEIGHT 240000 230000 220000 210000 200000 190000 180000 170000 160000 Forward Flight critical point 36 500 kg 150000 140000 130000 Takeoff Flight Landing 120000 110000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 INDEX 190 . the whole fuel vector between the critical point and fuel = 0 kg being inside the flight certified limit.Aft critical point: The aft critical point for the flight phase is defined as the forward one but with respect to the aft flight limits. BALANCE CHART DESIGN In flight phase . The fuel vector can be during flight outside the landing certified limit because of in-flight movements (pax and cabin attendants movements) that slightly modify aircraft CG compared to static situations (takeoff and landing). BALANCE CHART DESIGN Landing phase . the whole landing fuel vector between the critical point and fuel = 0 kg remaining inside the landing limit and the associated flight fuel vector remaining inside the flight envelope. E fuel weight aft = + E 2Inner tank aft + E 2 Outer tank aft + E 2 Center tank aft + . WEIGHT 240000 230000 220000 210000 200000 190000 180000 170000 160000 Forward Landing critical point 36 500 kg 150000 140000 130000 Takeoff Flight Landing 120000 110000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 INDEX 190 . And it is calculated for each individual tank.. E fuel weight fwd = − E 2Inner tanks fwd + E 2 Outer tanks fwd + E 2 Center tank fwd + .. Efuel weight = ± ∆Wfuel x (H-arm∆Wfuel .. WEIGHT 240000 230000 220000 210000 200000 190000 180000 170000 160000 150000 Aft Landing critical point 14 730 kg 140000 130000 Takeoff Flight Landing 120000 110000 50 60 70 80 90 100 110 120 130 140 150 160 170 180 INDEX 190 Fuel Weight inaccuracy (Efuel weight) is determined for the fuel quantity corresponding to the critical point.Aft critical point: The aft critical point for the landing phase is defined as the forward one but with respect to the aft landing envelope.WEIGHT AND BALANCE ENGINEERING C.Forward critical point: The forward critical point for the landing phase is defined as the contact point between landing fuel vector and forward landing certified limit. 160 Getting to Grips with Aircraft Weight and Balance ..H-armlimit) Then the total inaccuracy is determined considering each fuel tank weight inaccuracy independent from the other ones. Getting to Grips with Aircraft Weight and Balance 161 WEIGHT AND BALANCE ENGINEERING . (takeoff phase) − Inaccuracy on the Zero fuel limit design (flight and landing phase only in case of non takeoff protected Zero Fuel limit and on all three phases in case of takeoff protected Zero Fuel limit) Then the total inaccuracy is determined considering each inaccuracy independent from the other ones. BALANCE CHART DESIGN c) Total fuel inaccuracy The final fuel allowance includes the three above mentioned inaccuracies: − Fuel weight inaccuracy linked to FQI inaccuracy (all flight phases) − Inaccuracy on the fuel ∆index determination.C. an index inaccuracy has to be taken into account. 162 Getting to Grips with Aircraft Weight and Balance . in this case the computation is usually much more precise (without precomputation) and no inaccuracy is considered. The weight sum is then considered to be precise and no inaccuracy is taken into account. are considered usually to be precise enough not to take into account any inaccuracy. Depending of the rounding system of the index and on the method to determine the index value for each weight value.WEIGHT AND BALANCE ENGINEERING C. Note1 : the computerized systems rounded to the tenth or hundredth. The value of the inaccuracy in term of moment depends on the index formula chosen. BALANCE CHART DESIGN 3.5. Inaccuracy due to CG computation method The balance chart used to determine the aircraft CG position can be : − graphical − tabulated − computerized In each case the computation is based on − a sum of weights = DOW + Payload Weight +Fuel Weight − a sum of index = DOI + Payload ∆Index +Fuel ∆Index Each weight of the sum is rounded to the closest unit value. Each index and ∆index of the sum may be rounded to : − the closest index unit in the case of paper systems (graphical or tabulated) − the closest decimal (tenth or hundredth) in the case of computerized systems. The index inaccuracy is first determined analyzing the balance chart as a number of index units. Note2 : some computerized systems may be based directly on each item H-arm value and not on the item ∆index. 49… − … Note : The same examples apply for passenger ∆index table except that the weight is replaced by the number of passengers.203 +0 204 .5. BALANCE CHART DESIGN 3. For each weight range the ∆index range is 1 index value.611 +1 612 . In the above example : − For weight between 0 and 203 kg the ∆index value varies between 0 and 0. In those tables the user selects the ∆index corresponding to the weight or passenger number range he is considering. a) Tables with constant step in index Those tables are usually used for passengers and cargo ∆index for fuel ∆index tables with constant step in weight are used.49… − For weight between 204 and 611 kg the ∆index value varies between 0. CARGO n Weight (kg) ∆index 203 +1 611 +2 1018 +3 1426 +4 1833 +5 CARGO n Weight (kg) ∆index 0 +0 204 +1 612 +2 1019 +3 1427 +4 Building this type of table consists of determining the transition weights for which there is a step between one index value and the other.1018 +2 1019 .5 and 1. There are two methods to define index tables : − Tables with constant step in index − Tables with constant step in weight.1426 +3 1427 .1.C.1833 +4 E cargo index tables = ± E 2 cargo1index table + E 2 cargo2 index table + E 2 cargo3 index table + E 2 cargo4 index table + E 2 cargo5 index table E passenger index tables = ± E 2 cabin OA index table + E 2 cabin OB index table + E 2 cabin OC index table + K Getting to Grips with Aircraft Weight and Balance 163 WEIGHT AND BALANCE ENGINEERING . The inaccuracy due to one table is independent from the inaccuracies due to the other tables so : CARGO n Weight (kg) ∆index 0 .5 index unit in each table. So selecting the rounded figure the user generates an maximum inaccuracy of ±0. Tabulated balance chart inaccuracy On the tabulated balance chart the ∆index value for each item loaded is read in an index table. Ex: for weight of 6500 kg the ∆index is –3. BALANCE CHART DESIGN b) Tables with constant step in index Those tables are usually used for fuel ∆index or for all ∆index tables in the balance chart.WEIGHT AND BALANCE ENGINEERING C. For a weight value not presented in the table different solutions are available : − interpolation allowed : the user finds the ∆index by interpolating between the 2 closest ∆index values. WEIGHT DENSITY (kg/l) (kg) 3000 4000 5000 6000 7000 8000 0. In this case the maximum inaccuracy value is reached for the maximum range of ∆index between two weights and the inaccuracy value equals the ∆index range.5 index units. Ex: in the above table the maximum ∆index range is between 7000 kg and 8000 kg and corresponds to a maximum inaccuracy in index of ±1. Ex: in the above table the maximum ∆index range is between 7000 kg and 8000 kg and corresponds to a maximum inaccuracy in index of ±3 index units. The inaccuracy due to one table is independent from the inaccuracies due to the other tables so : E cargo index tables = ± E 2 cargo1index table + E 2 cargo2 index table + E 2 cargo3 index table + E 2 cargo4 index table + E 2 cargo5 index table E passenger index tables = ± E 2 cabin OA index table + E 2 cabin OB index table + E 2 cabin OC index table + K 164 Getting to Grips with Aircraft Weight and Balance . In this case the maximum inaccuracy value is reached for the maximum range of ∆index between two weights and the inaccuracy value equals half the ∆index range. Ex: for weight of 6500 kg the ∆index is –2 (–4). the user always retains the value corresponding to the lowest (highest) weight. − interpolation is not recommended by the operator procedure.785 +2 +1 +0 –2 –4 –7 In those tables the user selects the ∆index corresponding to the weight or passenger number he is considering. 5 cm. Graphical balance chart inaccuracy On the graphical balance chart the ∆index value for each item loaded is read on a diagram. Following these design rules it is assumed that on each scale the maximum inaccuracy is of 0.C. AIRBUS standard constants are determined in order to have a major step in index length drawn on the chart between 1 and 1. The inaccuracy due to one scale is independent from the inaccuracies due to the other scales so : E cargo index tables = ± E 2 cargo1index table + E 2 cargo2 index table + E 2 cargo3 index table + E 2 cargo4 index table + E 2 cargo5 index table E passenger index tables = ± E 2 cabin OA index table + E 2 cabin OB index table + E 2 cabin OC index table + K Getting to Grips with Aircraft Weight and Balance 165 WEIGHT AND BALANCE ENGINEERING . On this diagram the ∆index is drawn manually on each line for each item loaded. Then the cargo weight steps and passenger number steps on the diagram are determined so that between two oblique lines on the scale there is no more than 5mm to ensure sufficient accuracy when interpolating.5.5 index unit.2.5 mm. The manual drawing generates an inaccuracy due to the drawing precision as illustrated below : the blue line being the ideal drawing and the red line a manual drawing. The inaccuracy due to this manual input is highly dependant on the index scale readability on the balance chart and the index scale is linked to the choice of index formula C constant. each major step is divided into 10 minor steps so one minor step length is between 1 and 1. BALANCE CHART DESIGN 3. 5. − determining ∆index for each cargo compartment (5 scales) − determining ∆index for each cabin section (3 scales) − determining the fuel ∆index in the fuel index table (inaccuracy depends on the weight step in the table.5 2 + 2 2 = ±2. and on the procedure interpolation/no interpolation) in this example inaccuracy = 2 index units. 166 Getting to Grips with Aircraft Weight and Balance .5 2 + 5 × 0.3.55 index units = ± 2.55 index unit ∆Index = Moment Moment = C 2500 ECG determination method = ±2.5 2 + 3 × 0.5 2 + 2 2 + 0. E CG determinat ion E CG determinat ion E CG determinat ion method method method = ± E 2 inital scale + 5 × E 2 Cargo scale + 3 × E 2 Cabin section scale + E 2 fuel table + E 2 fuel scale = ± 0.m. example on A330 graphical balance chart On this balance chart the final CG is determined − entering the Dry Operating Index in the initial scale.WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN 3. − entering the fuel index in the fuel scale Each inaccuracy scale is independent from the other ones.55 x 2500 = ± 6374 kg.5 2 = ± 10 × 0. passengers and crew members move together with the trolleys. some operators may use a different configuration. The computed aircraft CG positions during the flight are computed for a given configuration in the cabin. BALANCE CHART DESIGN 3. Crew… Getting to Grips with Aircraft Weight and Balance 167 WEIGHT AND BALANCE ENGINEERING . Landing Gear. Revesers. These differences in aircraft configuration have to be taken into account when checking the CG position against the relevant certified CG limits. these movements generate a shift of the aircraft CG position. Note : on all the aircraft the movement of the reversers is considered negligible in term of CG movements so they are no more considered below. introducing an additional moment in the operational margin. This configuration corresponds to the aircraft configuration used at aircraft weighing. During the flight. Passenger. Note : the above mentioned configuration at DOW is the most common one. In this case the below presented method has to be adapted.C. Water.6. Eaircraft CG movement = Real Aircraft Moment – Balance Chart Aircraft Moment Eaircraft CG movement = Moment due to item movement Item being : Flaps/Slats. Item movements during flight impacting the aircraft CG position Aircraft CG positions computed on the balance chart are based on DOW and DOCG values. DOW and DOCG values are published for the following configuration : − Flaps/slats in clean position − Landing Gear extended − Reversers in retracted position − Water in potable water tanks. passengers and crew seated in Takeoff/Landing configuration and trolleys locked in the galleys. 168 Getting to Grips with Aircraft Weight and Balance .00. there is no risk of being out of the limits as the operational configurations will always lead to a more forward CG than the estimated one. In reality Takeoff configuration is Flaps/slats extended. For the forward certified CG operational margins determination. the total resulting moment for takeoff and landing possible configuration moves it aft so the real takeoff and landing CG will always be aft of the estimated value.WEIGHT AND BALANCE ENGINEERING C.1. Landing gears retraction moves the aircraft CG forward so the real in flight CG will always be forward of the estimated value. there is no risk of being out of the limits as the operational configurations will always lead to a more aft CG than the estimated one. Flaps/Slats and Landing gear movements Estimated TOCG F/S clean LDG down Estimated Flight CG F/S clean LDG down Estimated LDCG F/S clean LDG down DOW and DOCG values are published for the following configuration : − Flaps/slats in clean position − Landing Gear extended So on the balance chart all the aircraft CG values correspond to this configuration.6. Landing configuration is Flaps/slats extended and Flight configuration is landing gear retracted. DOCG F/S clean LDG down TOCG F/S extended LDG down Flight CG F/S clean LDG up LDCG F/S extented LDG down DOCG F/S clean LDG down Flaps extension moves the aircraft CG aft. Nevertheless it is possible to take benefit of this situation by taking into account this CG movement is reducing the aft operational margin. For the aft certified CG operational margins determination. Nevertheless it is possible to take benefit of this situation by taking into account this CG movement is reducing the forward operational margin. BALANCE CHART DESIGN 3. Slats extension moves it forward. Eaircraft CG movement = Moment due to Flaps/Slats or Landing Gears movement The moments generated by Flaps/Slats and Landing Gears movement are published in the WBM in section 1. So for aft certified CG operational margins determination the maximum aft movement has to be taken into account to prevent the aircraft CG being out of the limits. So for forward certified CG operational margins determination the maximum forward movement has to be taken into account to prevent the aircraft CG being out of the limits. m or EMain gear + ENose gear Getting to Grips with Aircraft Weight and Balance 169 WEIGHT AND BALANCE ENGINEERING . Impact on forward operational limit : Eaircraft CG movement = 0 kg.m or ECONF 3 Impact on aft operational limit : Eaircraft CG movement = ECONF FULL = + 476 kg.m or ECONF 1+F Impact on aft operational limit : Eaircraft CG movement = ECONF 3 = + 368 kg. CONF 2. BALANCE CHART DESIGN • ex : A330-200 Flaps and Slats movements : Takeoff configuration : the possible configurations are CONF 1+F. CONF 3. Impact on forward operational limit : Eaircraft CG movement = 0 kg.6677 kg.m Landing configuration : the possible configurations are CONF 3.m Impact on aft operational limit : Eaircraft CG movement = 0 kg.m Landing Gears movements : Flight configuration : Nose and Main landing gears retracted Impact on forward operational limit : Eaircraft CG movement = EMain + ENose = . CONF FULL.C. 6. 170 Getting to Grips with Aircraft Weight and Balance . BALANCE CHART DESIGN 3. Eaircraft CG movement = Moment due to item movement = Moment due to water movement from potable tanks to waste tanks + Moment due to water ejection. In reality at landing part of the water is located in the waste tanks and part of the water has been ejected out of the aircraft. Water movement from potable to waste tank Estimated TOCG Water in Potable water tanks Estimated Flight CG Water in Potable water tanks Estimated LDCG Water in Potable water tanks DOCG Water in Potable water tanks Flight CG Water moving between potable tanks and waste tanks LDCG Water in waste tanks DOCG Water in Potable water tanks DOW and DOCG values are published for the following configuration : − Water is located in the potable water tanks.2. So on the balance chart all the aircraft CG values correspond to this configuration.WEIGHT AND BALANCE ENGINEERING C. C. BALANCE CHART DESIGN Eaircraft CG movement = WWater in waste tank x (H-armfinal position – H-arminitial location) + WWater ejected x (H-armfinal – H-arminitial location). Eaircraft CG movement = WWater in waste tank (H-armwaste tank – H-armpotable water tank) - WWater ejected x H-armpotable water tank. Position of the different tanks in the aircraft are published in WBM 1.30 • position ex : A330-200 Takeoff configuration 700 kg of water in the potable water tanks. Landing configuration : - 1/3 of the water ejected out of the aircraft, - 2/3 of the water in the waste tank. Eaircraft CG movement = WWater in waste tank (H-armwaste tank – H-armpotable water tank) - WWater ejected x H-armpotable water tank. 2 52.587 + 52.369 39.167 + 51.691 1 39.167 + 51.691 E aircraft CG movement = × 700 × − − × 700 × 3 2 2 2 3 Eaircraft CG movement = 3289.53 – 10600.1 = - 7310.57 kg.m Getting to Grips with Aircraft Weight and Balance 171 WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN 3.6.3. In flight passenger and crew movements Flight CG Passengers and crew moving DOCG On the balance chart all the aircraft CG values are based on the passenger and crew position at takeoff. We consider that at landing the configuration is identical to the takeoff one. During the flight passengers and crew are moving throughout the cabin. Eaircraft CG movement item = Moment due to item movement Eaircraft CG movement item = Witem x (H-armItem final position – H-armItem initial location) The estimation of the possible inflight movements depends on the airline operations, on the cabin layout, on the flight type… The objective is to determine realistic impact on the aircraft CG during the flight by considering the different periods of the flight when there are movements in the cabin : − Meal servicing, − Passengers moving to the lavatories − Crew moving to the crew rest areas − Duty free sells − … Some of these movements may happen simultaneously, some will move the aircraft CG forward, some will move it aft. A standard movement scenario is used in Airbus standard method : − All movements are defined based on initial position of the item or person at takeoff. − Galleys, lavatories and crew are assigned per passenger class, and movements are performed within each class section. − All movement in one direction (forward/aft) happen simultaneously. − There is one passenger per lavatory, when 2 lavatories are available for the same passenger section then 2 passengers from the middle of the section move toward them at the same time. − There is one cabin crew and one trolley per aisle for meal servicing. − When underfloor crew rest or crew rest area is defined in the cabin, then additional movements towards the rest area are taken into account. Crew members form the whole cabin are moving. − Additional movement may be added : cabin crew to the cockpit, cockpit crew to cabin area. This scenario enables to establish for each item or person moving Eaircraft CG movement item = Witem x (H-armItem final position – H-armItem initial location), then as all movement in one direction (forward/aft) happen simultaneously, the total Eaircraft CG movement is the sum of each individual Eaircraft CG movement item. 172 Getting to Grips with Aircraft Weight and Balance C. BALANCE CHART DESIGN • ex : A330-200 movements forward Cabin attendant La G1 G2 Lb Lc G G 3 4 Ld Lf Le Lg G5 G5 G6 G6 2 B class pax from row 4 to La and Lb 2 Eco class pax from row 21 to Lc and Ld 2 trolleys from G5/G6 to pax row 18 1 cabin crew from forward position to cockpit 2 cabin crew from aft positions to pax row 18 Forward movements are split into 3 movements for each movement Eaircraft CG movement item = Witem x (H-armItem final position – H-armItem initial location) needs to be determined. Witem depends on the operator assumptions, passenger or crew member weights are defined without hand luggage. Eg : for average pax weight = 84 kg, the pax weight considered for the movement is (average pax weight – hand baggage weight) = 84-9 = 75 kg. H-armItem final position and H-armItem initial location are published in the weight and balance manual in the 1.40 and 1.50 sections. 1. passenger movements : 2 business class passengers to business class lavatories Eaircraft CG movement 2 pax from row 4 to La/Lb = W2 pax x (H-armLa/Lb – H-armRow4) a b c d Eaircraft CG movement 2 pax from row 4 to La/Lb = 2x 75 x (10.755 – 16.933) = - 926.7 kg.m Getting to Grips with Aircraft Weight and Balance 173 WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN 2 economy class passengers to economy class lavatories Eaircraft CG movement 2 pax from row 21 to Lc/Ld = W2 pax x (H-armLc/Ld – H-armRow21) Eaircraft CG movement 2 pax from row 21 to Lc/Ld = 2x 75 x (19.627 – 33.360) = - 2059.95 kg.m 2. Trolley movements 2 trolleys from G5/G6 to passenger row 18 Eaircraft CG movement 2 trolleys from G5/G6 to row 18 = W2 trolleys x (H-armRow 18 – H-armG5/G6) Eaircraft CG movement 2 trolleys from G5/G6 to row 18 = 2 x 80 x (30.77–54.064) = - 3727.04 kg.m 3. Crew members movements 2 cabin crew from aft positions to passenger row 18 Eaircraft CG movement 2 cabin crew from aft position to row18 = W2 cabin crew x (H-armRow18 – H-armaft) Eaircraft CG movement 2 cabin crew from aft position to row18 = 2x70 x (30.77–55.21) = -3421.6 kg.m 1 cabin crew from forward position to cockpit Eaircraft CG movement 1 cabin crew from fwd position to cockpit = W1 cabin crew x (H-armcockpit – H-armfwd) Eaircraft CG movement 1 cabin crew from fwd position to cockpit = 70 x (8.872–11.575) = -189.21 kg.m Total forward movements : Eaircraft FWD CG movement = Eaircraft CG movement 2 pax from row 4 to La/Lb + Eaircraft CG movement 2 pax from row 21 to Lc/Ld + Eaircraft CG movement 2 trolleys from G5/G6 to row 18 + Eaircraft CG movement 2 cabin crew from aft position to row18 + Eaircraft CG movement 1 cabin crew from fwd position to cockpit Eaircraft FWD CG movement = - (926.7 + 2059.95 + 3727.04 + 3421.6 + 189.21) = - 10320.5 kg.m 174 Getting to Grips with Aircraft Weight and Balance C. BALANCE CHART DESIGN 3.7. Total operational margins determination The total operational margins per flight phase are determined summing each individual margin, some of them being considered as systematic, the other ones as non systematic. Systematic / OPERATIONAL MARGIN Non systematic Inaccuracy on initial data (DOW and DOCG) Non Syst Inaccuracy on items loading on board the aircraft (passengers, cargo, fuel) Inaccuracy on the passengers’ Non Syst location Passenger loading Inaccuracy on the passengers’ Non Syst weight Inaccuracy on the cargo Non Syst location Cargo loading Inaccuracy on the cargo weight Non Syst Inaccuracy on the fuel location Non Syst Fuel loading Inaccuracy on the fuel weight Non Syst Inaccuracy due to CG computation method Manual balance chart Non Syst Computerized balance chart Item movements during flight impacting the aircraft CG position Flaps/Slats movements Syst Landing gear movements Syst Water movement from potable to waste tank Syst In flight passenger and crew movements Syst 2 2 Aircraft CG affected TO LD IF X X X X X X X X X X X X X X X X X X X X X X X X X X X X X FWD margin flight phase1 = − FWDmarginNON Systematic 1 + ... + FWDmarginNON Systematic n + FWDmarginSystematic 1 + ... + FWDmarginSystematic n AFT marginflight phase1 = + AFTmarginNON Systematic 1 + ... + AFTmarginNON Systematic n + AFTmarginSystematic 1 + ... + AFTmarginSystematic n 2 2 Getting to Grips with Aircraft Weight and Balance 175 WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C.754 20.573 976 818 982 114 18. Takeoff.E W × H − armcertified − E 100 − LEMAC × W W x H-armcertified .431 18.8015 MomentCertified = H-armCertified x Weight Moment0perational = MomentCertified – (.8015) / 0.m Operational margin kg. BALANCE CHART DESIGN 3.514 18.33 1 166 406 1 171 703 18.10 tables presenting A/c Certified Weight = W and A/c Certified CG limit (%RC) = CG.588 1 366 664 1 371 961 18.393 17. 176 Getting to Grips with Aircraft Weight and Balance . Certified limits Flight phase Weight CG (%RC) CG (H-arm) Aircraft Moment on certified limit W CGcertified H-armcertified MAC × CG MAC × CG LEMAC × W × LEMAC × W CG 100 100 Total operational margin Flight phase = E Operational limits Flight phase Weight Aircraft Moment on CG (H-arm) CG (%RC) W operational limit H-armoperational CGoperational W x H .9 H-armcertified m 18.armcertified .431 18.041935 Weight Certified forward limit Operational forward limit Moment The complete computation leads to the determination of each individual operational limit.598 1 333 036 1 338 333 18.530 .5 296. In-Flight operational limits determination When total operational margins per flight phase are determined they are applied to each corresponding certified limit to obtain the operational limits per flight phase.383 19.618 l Weight W kg 37320 53000 63000 72000 73500 15% 17% 19% 21% Operational margin 686 168 691 465 18. Landing.666 H-armCertified = (CGCertified x 0. Certified limits are published in the WBM 1.041935) + 17.m H-armoperational m CGoperationa %RC 18.5 296.E W MAC W • ex : A320-200 Takeoff forward operational limits determination Certified limit CGcertified %RC 15 15 17 17 18.594 Moment kg.005 18.8.514 18.33) H-armoperational = Moment0perational / Weight CGoperational = (H armoperational – 17.m Operational limit Moment kg. So only a Takeoff limit is drawn on the Load and Trim Sheet. So the forward operational limit published on the balance chart or in the AHM560 is made of part of the In Flight limit and part of the Takeoff limit.C. it is hardly possible to check these CG positions against their corresponding CG limits. this takeoff limit is the more limiting one of the three operational limits. the determination of the Landing CG and furthermore the In-flight CG positions on a paper document is much more difficult. BALANCE CHART DESIGN In Flight limits Takeoff limits Landing limits Operational Limits On the balance chart the 3 operational limits – Takeoff. Getting to Grips with Aircraft Weight and Balance 177 WEIGHT AND BALANCE ENGINEERING . depending on the values of each operational margins. And this specially for low aircraft weights. Note often on A320 documents the forward In Flight limit is more limiting than the Takeoff one. Landing and In-flight – are not represented because if the Takeoff CG position check against its corresponding limit can be done after a manual or computerized computation. WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN 3.9. Zero Fuel limit determination 3.9.1. Definition of the Zero Fuel Limit On the balance chart it is necessary to check the Takeoff CG position against the Takeoff operational limit, this ensures that the aircraft CG position is within the certified takeoff limit. Nevertheless this check is not sufficient to ensure that the aircraft CG remains within the in flight and landing limits during the whole flight. This second check cannot be made easily by checking the landing CG position and the different flight CG positions because of the difficulty to estimate these values. To perform this check an additional limit has been introduced : the Zero Fuel Limit. The Zero Fuel limit is determined to ensure that during the whole flight and at landing the aircraft CG remains within the limits. 3.9.2. Zero Fuel limit computation method Two different methods are used to determine the Zero Fuel limit, depending on procedure applied on the balance chart. a) Zero fuel limit takeoff protected : IF Zero fuel CG is within the Zero fuel limit And IF takeoff weight and landing weight are compliant with the operational takeoff and landing maximum weights. THEN Takeoff, Landing and In Flight CG are within the allowed limits using the whole flight. With this type of limit, assuming that the takeoff and landing weight limitations are checked on the AHM516 (Load Message) the only check to be performed on the balance chart is to ensure that the Zero Fuel CG position is within the Zero Fuel limit. − − b) Zero fuel limit not takeoff protected : IF Zero fuel CG is within the Zero fuel limit IF Takeoff CG is within the Takeoff operational limit And IF takeoff weight and landing weight are compliant with the operational takeoff and landing maximum weights. THEN Takeoff, Landing and In Flight CG are within the allowed limits using the whole flight. With this type of limit, assuming that the takeoff and landing weight limitations are checked on the AHM516 (Load Message) the check to be performed on the balance chart is to ensure that the Zero Fuel and Takeoff CG position are within the Zero Fuel and Takeoff operational limits. − − − c) Computation method : For each type of Zero Fuel limit the calculation principle is the same, it consists in : − Determining the possible aircraft CG position at Takeoff, Landing and Flight provided the Zero Fuel CG position is known, by analyzing the fuel vectors applicable to each flight phase. (refer to Fuel System Chapter). − Using the fuel vectors, determining all the allowed Zero Fuel CG positions so that all possible takeoff (for takeoff protected limit), landing and in flight CGs remains within their operational limits from no fuel to maximum fuel quantity. 178 Getting to Grips with Aircraft Weight and Balance C. BALANCE CHART DESIGN 3.9.3. Zero Fuel limit computation example : A320 The computation is based on the operational limits previously determined and on the possible CG positions at takeoff, landing and in flight for a given Zero Fuel CG position, these positions are given by the different fuel vectors. For A320 family aircraft the takeoff, in flight and landing fuel vectors are identical. a) Zero fuel limit takeoff protected : Each flight phase fuel vector is leaned against the corresponding operational limit. In the case of A320 aircraft the fuel vector is leaned against the more inside operational limit. This operation is repeated for Zero Fuel weights between minimum aircraft weight and Maximum Certified Zero Fuel Weight. For this example the final result is the pink area above. Note : This area is determined for all fuel quantities between 0 to maximum fuel quantity. But if the fuel quantity is lower than maximum fuel quantity the resulting Zero Fuel limit would be larger than the one above. So some operators using the takeoff protected Zero Fuel limit may chose to have several limits presented depending on the takeoff fuel quantity. Getting to Grips with Aircraft Weight and Balance 179 WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN b) Zero fuel limit not takeoff protected : Landing and flight phase fuel vector are leaned against the corresponding operational limit. In the case of A320 aircraft the fuel vector is leaned against the more inside operational limit between landing and flight. The takeoff limit is not used as the takeoff CG position is supposed to be checked within the operator procedure. On the forward limit, the final part of the vector, which corresponds to the center tank refueling or consumption, is not taken into account (it goes out of the operational limits on the graph). This optimization is made to enlarge as much as possible the Zero Fuel limit. It is possible because the takeoff CG position is checked and because the fuel burn in the center tank shifts the aircraft CG aft. So it ensures that if the takeoff CG is within of the takeoff operational limit then the other CG positions will remain in the limits also during the whole flight. This operation is repeated for Zero Fuel weights between minimum aircraft weight and Maximum Certified Zero Fuel Weight For this example the final result is the pink area above. Note : In this case the Zero Fuel limit is optimized and there is no need to have different limits for different fuel quantities. 180 Getting to Grips with Aircraft Weight and Balance C. BALANCE CHART DESIGN 4. BALANCE CHART DRAWING PRINCIPLE A balance chart is made of several parts – the ∆index scales or tables and the operational limits graph. The aim of this chapter is to explain the way to draw the different parts. LOAD and TRIM SHEET DRY OPERATING WEIGHT CONDITIONS WEIGHT (kg) H-arm (m) AIRCRAFT REGISTER : DRY OPERATING WEIGHT WEIGHT DEVIATION (PANTRY) DATE : PREPARED BY : CORRECTED DRY OPERATING WEIGHT CARGO FLT Nbr : I= (H-arm - 33.1555) x W + 100 5000 CAPT. SIGNATURE : PASSENGERS ZERO FUEL WEIGHT FROM : TO : TOTAL FUEL ONBOARD TAKEOFF WEIGHT INDEX CORRECTION ZONES ZONES WEIGHT DEVIATION (kg) E F G H PAX E OA (18 PAX) ROW 1 TO 3 A G1c Ln 1 2 3 G2 1 A G1 2 3 Lk1 A G3 A 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Lo A 1 2 3 A Lh1 12 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 A Lh2 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 G7 12 14 15 16 17 18 A330-243 VERSION : 18 BC-264 YC ± = + x 8 4 = + = + = DRY OPERATING WEIGHT INDEX F OB (152 PAX) ROW 12 TO 31 19 20 21 22 23 24 25 26 27 28 29 30 31 Lk2 A Lp 32 33 34 35 36 37 38 39 40 41 42 43 44 45 32 33 34 G OC (112 PAX) ROW 32 TO 46 35 36 37 38 39 40 41 42 43 44 45 46 G5 A G6 A BASIC INDEX CORRECTION DRY OPERAT. WEIGHT DEVIATION +300 kg -300 kg ZONES E -1.30 +1.30 F -0.82 +0.82 G +1.22 -1.22 H CARGO 1 (18869 kg) 2 3 (15241 kg) 4 5 (3468 kg) INDEX CORRECTION ZONES CARGO 1 CARGO 2 CARGO 3 CARGO 4 CARGO 5 CABIN OA CABIN OB CABIN OC Nbr WEIGHT(kg) 70 80 CORRECTED INDEX 90 100 110 120 ALL WEIGHTS IN KILOGRAMS 130 140 INDEX 500 kg 500 kg 500 kg 500 kg 250 kg 10 PAX 40 PAX 15 PAX FUEL INDEX SEE TABLE OVERLEAF 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 - INDEX + Aircraft CG (%MAC) NOTES MTOW = 230000 kg 230 220 210 200 Aircraft Weight (kg x 1000) 190 MLW = 180000 kg 180 170 160 150 140 130 OPERATIONAL LIMITS 120 110 TAKEOFF ZFW MZFW = 168000 kg TAKEOFF CG % MAC ZFW CDU INPUT WEIGHT (kg x 1000) INDEX 70 80 90 100 110 120 130 140 . . AIRCRAFT CG 18 %MAC % MAC PITCH TRIM 20 Constant 7 22 6 24 5 26 4 28 3 30 2 32 1 34 0 36 38 Constant 40 . Nose Up Nose Down Getting to Grips with Aircraft Weight and Balance 181 WEIGHT AND BALANCE ENGINEERING WEIGHT AND BALANCE ENGINEERING C. BALANCE CHART DESIGN 4.1. ∆index scales or tables for loaded items 4.1.1. Graphical balance chart On the graphical balance chart the ∆index value for each item loaded – passenger or cargo – is read on a diagram. One scale per cargo compartment and one scale per passenger cabin section are represented. The scales are made of oblique lines, with distance between 2 lines representing the ∆index corresponding to the individual cargo weight or passenger number, usually presented on the right end of each scale. The oblique lines have been introduced in order to ease the manual drawing on the document. Indeed the first possibility is to have vertical lines but is it difficult to determine the end point of the drawing. ∆Index XXX kg XX pax Pitch Whereas with oblique line the horizontal and vertical lines can be more easily drawn. ∆Index XXX kg XX pax Pitch To draw the pitch between two line use the ∆index(1 kg) value. ∆Index item (1kg) = (H − arm item − HRef ) and determine the ∆index(XXX kg) or ∆index(XX PAX) C needed on the balance chart. Note 1 : the horizontal distance between the oblique line top and bottom points represents exactly ∆index(XXX kg) or ∆index(XX PAX) on the index scale. Note 2 : the oblique line orientation : from top right to bottom left in case of forward CG movement, and from top left to bottom right in case of aft CG movement when loading the item must be strictly applied, because of the habits taken when manually using a balance chart. A change in the orientation may lead to misusing of the document. 182 Getting to Grips with Aircraft Weight and Balance WEIGHT DENSITY (kg/l) (kg) 3000 4000 5000 6000 7000 8000 0. 4.203 +0 204 . nevertheless today due to the complexity of the refuel vectors and the high impact of fuel density on the fuel vector.49… − For weight between 204 and 611 kg the ∆index value varies between 0. Getting to Grips with Aircraft Weight and Balance 183 WEIGHT AND BALANCE ENGINEERING .C.1833 +4 b) Tables with constant step in weight Those tables are usually used for fuel ∆index or for all ∆index tables in the balance chart.49… − … CARGO n Weight (kg) ∆index 0 .1. CARGO n Weight (kg) ∆index 203 +1 611 +2 1018 +3 1426 +4 1833 +5 CARGO n Weight (kg) ∆index 0 +0 204 +1 612 +2 1019 +3 1427 +4 Building this type of table consists of determining the transition weights for which there is a step between one index value and the other. this graphical method is no more used for Airbus aircraft. Tabulated balance chart a) Tables with constant step in index Those tables are usually used for passengers and cargo ∆index for fuel ∆index tables with constant step in weight are used. In the above example : − For weight between 0 and 203 kg the ∆index value varies between 0 and 0. depending on the airline procedure.5 and 1.1426 +3 1427 .2.785 +2 +1 +0 –2 –4 –7 Building this type of table consists of determining the ∆index(XXX kg) and rounding it to the closest unit or closest tenth.1018 +2 1019 .611 +1 612 . BALANCE CHART DESIGN Note 3 : the fuel loading ∆index used to be drawn on similar scales for some specific aircraft. 2. It is based on the index formula expressed in %RC. BALANCE CHART DESIGN 4. • For CG = Ref% then Index = Weight × (Ref% . Index = With: Weight × (%RC .Ref%) × MAC + K C Index = K. Therefore the Ref% the iso-CG line is a straight line associated to index = K.WEIGHT AND BALANCE ENGINEERING C. Ref % Weight Index = K Index 184 Getting to Grips with Aircraft Weight and Balance .Ref%) × MAC + K C C and K constants depending on the aircraft type MAC = Mean Aerodynamic Chord of the aircraft. whatever the weight value. Operational limits diagram The operational limits are represented on a diagram − on X-axis the aircraft index values − on Y-axis the aircraft weight values Then iso-CG lines are represented to enable the user to determine finally the aircraft CG position value in %RC. Ref%) × MAC + K and Index 2 = 2 × MAC + K C C Weight Ref+1 Ref+3 Ref-3 Ref-1 Ref-2 Ref % Ref+2 Ref+4 Index = K Index When the diagram is prepared the operational limits can be drawn on it : − “takeoff” operational limit (the limit resulting from the operational margins computation and the selection of the more limiting part between takeoff. Getting to Grips with Aircraft Weight and Balance 185 WEIGHT AND BALANCE ENGINEERING . BALANCE CHART DESIGN • For other CG values then: The index values corresponding to two weights W1 and W 2 are linked by the iso-CG line.Ref%) W (CG a .C. landing and in flight operational limits) − zero fuel operational limit. Index 1 = W1 (CG a . 1. a Loading Instruction/Report. THE AHM560 The AHM560 is a standardized IATA document containing weight and trimming data necessary for both the aircraft CG position and the operational limits calculations.). BALANCE CHART DESIGN 5. a LDM. Part of this document contains the results from the balance chart design process. information given in the AHM560 can be applied to several aircraft registrations. It also lists all the documents that need to be produced by the EDP system. a NOTOC. The aircraft type. other information is linked to operators’ needs in term of EDP system computation and EDP system output. a CPM. 5. A specific AHM560 should be used by airlines for each type of aircraft they have. The supplemental documents are for instance a Loadsheet. etc. The computerized balance chart systems (EDP systems) are based on the data provided in the AHM560.WEIGHT AND BALANCE ENGINEERING C. same cabin layout. same certified limits. PART A: COMMUNICATION ADDRESSES This part provides with the handling agents' and the carrier' addresses. provided those aircraft have the same Weight & Balance characteristics (same weight variants. … 186 Getting to Grips with Aircraft Weight and Balance . Generalities The AHM560 is divided into four main parts: − PART A: COMMUNICATION ADDRESSES − PART B: GENERAL INFORMATION − PART C: AIRCRAFT DATA − PART D: LOAD PLANNING DATA Each part is divided into several Sheets.2. the airline code and the part and sheet number of each page are written in the header as follows: 5. that correspond to different types of data. 1.4.C. 5. Getting to Grips with Aircraft Weight and Balance 187 WEIGHT AND BALANCE ENGINEERING .2. C Sheet 2 C Sheet 2 contains the aircraft list for which the document is applicable and their definition in term of Dry Operating Weight or Basic Weight. as well as the list of items taken into account for the Dry Operating Weight (DOW) and Dry Operating Index (DOI) calculation.4. PART B: GENERAL INFORMATION Part B is a summary of weight data used by the airline : passenger weights (Male / Female / Children / Infants).3. C Sheet 1 C Sheet 1 contains the information the operator needs to be shown on the EDP system Loadsheet output and the way the operator has chosen to determine the passenger loading influence on aircraft CG position. PART C: AIRCRAFT DATA This part contains the aircraft detailed list for which the document is applicable with the aircraft definition in term of weights and index and all the trimming data. 5.4. crew weights and cabin baggage weights. BALANCE CHART DESIGN 5. 5. 4. C Sheet 5 C Sheet 5 gives the ∆index to be used to determine the influence of items or persons in the cockpit.3. there may be only one fuel table for the standard fuel density used by the operator of several tables for a range of densities.4.4. C Sheet 4 C Sheet 4 contains the fuel index tables.4. 5. − “takeoff” operational limit (the limit resulting from the operational margins computation and the selection of the more limiting part between takeoff. 5. C Sheet 6 C Sheet 6 contains the aircraft list for which the document is applicable (same list as in C Sheet 2) and their definition in term of maximum weights. Note : for all aircraft equipped with a trim tank it is recommended to issue several tables for different densities. with the exact values of constants and aircraft data that enter in this formula. the stabilizer trim setting is given in function of the MAC value at takeoff.5. C Sheet 7 C Sheet 7 contains the operational limits to be used for CG checks in the EDP system. BALANCE CHART DESIGN 5. C Sheet 3 C Sheet 3 is a reminder of the index formula used for index calculation.7. At the bottom of this sheet. landing and in flight operational limits) − zero fuel operational limit.4. 5. 188 Getting to Grips with Aircraft Weight and Balance . 5.WEIGHT AND BALANCE ENGINEERING C.4.6. Getting to Grips with Aircraft Weight and Balance 189 WEIGHT AND BALANCE ENGINEERING . details about ULD (containers and pallets) in D Sheet 2. and regulations about special loads transportation in D Sheet 3.4. C Sheet 14 gives the ∆index to be used to determine the influence of cargo loading per cargo position. 5. C Sheet 9 gives the ∆index to be used to determine the influence of passenger loading per cabin section. 5.8. 5.C. PART D: LOAD PLANNING DATA This part is composed of sheets to enter general miscellaneous information such as the ideal trim line data in D Sheet 1. It also enables to indicate the type of seat used in the cabin.4. C Sheet 8. BALANCE CHART DESIGN 5. 10 C Sheet 8 details the cabin sections defined by the operator to determine the passenger loading influence per section. 12 C Sheet 11 and 12 gives the ∆index to be used to determine the influence of any cabin crew. C Sheet 15 C Sheet 15 details the operator’s procedure for ballast carriage. 9.4.5. C Sheet 11. any item in the galleys and any pantry. C Sheet 10 gives the ∆index to be used to determine the influence of passenger loading per seat row.10. C Sheet 13. 5.4.9.11. 14 C Sheet 13 gives the ∆index to be used to determine the influence of cargo loading per cargo compartment. . The LTS software enables also to produce specific data files that are used by the Weight&Balance module of the Less Paper Cockpit package. A310. AHM516 and AHM515 documents for any Airbus model: A319. A300. Getting to Grips with Aircraft Weight and Balance 191 WEIGHT AND BALANCE ENGINEERING . These loading and trimming documents are generated from the weight and balance characteristics of the aircraft supplied in a database. A321. INTRODUCTION The Load and Trim sheet software enables the Airbus operators to produce a load and trim sheet and its associated AHM560.D. from the assumptions set by the user and from the cabin arrangement defined for the aircraft. A330 and A340 except for freighter and combi aircraft. A320. LOAD AND TRIM SHEET SOFTWARE D. − To reduce the production time of the loading and trimming documents. OBJECTIVES The main objectives of this software are the electronic distribution and update of the Weight&Balance data of Airbus aircraft and the calculation and creation of the loading and trimming documents. This software allows: − To improve access time to the information. − To ensure technical data accuracy − To propose a user-friendly interface to visualize and update the Weight & Balance data. the cargo distribution or the fuel management. − To perform the error calculation required for the operational envelopes determination. This software allows the Airbus operators to quickly produce and update these documents following any aircraft modification affecting the certified limits. the passenger distribution. 2. LOAD AND TRIM SHEET SOFTWARE 1. The modifications enumerate the weight variant certified for the aircraft. LOAD AND TRIM SHEET SOFTWARE 3. The interface of the LTS program allows the user to perform with several tasks described below. Unit system: It is possible to select the unit system either metric or US system. the LTS program uses a database containing a complete set of assumptions and data. − The Airbus default settings and the user’s personal settings for various parameters such as the index formula. 3.2.WEIGHT AND BALANCE ENGINEERING D. the passengers’ average weights… − The cabin layout data. the fuel system installed on the aircraft… 192 Getting to Grips with Aircraft Weight and Balance . The loading and trimming documents are generated for any aircraft of the user’s fleet. The selection of the relevant aircraft is performed at the interface initialization. The program structure relies on a relational database that stores the following pieces of information: − The weight and balance data for all the MSN of the operator. SOFTWARE DESCRIPTION First of all. Aircraft modifications: It is possible to consult the aircraft modifications validated for the aircraft chosen. the cargo configuration.1. These data will be updated and sent to the operator by Airbus at each aircraft modification affecting the loading and trimming. 3. the program can select any of the available cargo options: Bulk. The update function allows to select a new weight variant and/or a new certified CG envelope that has been approved in the Aircraft Flight Manual. installation of an ACT (Auxiliary Center Tank) or an UCRC (Under Crew Rest Container)… For instance. the user can: − Set the index formula. − Consult and update the cargo holds’ characteristics. Getting to Grips with Aircraft Weight and Balance 193 WEIGHT AND BALANCE ENGINEERING . for the A320 family. The update function enables to take into account the modifications that can be carried out in the cargo holds: installation of a new cargo system. − Consult the tanks’ characteristics and the fuel management curve. Aircraft configurations: Through the Aircraft Configuration frame. CLS and Occasional Bulk… − Consult and update the certified design weights and the certified design CG limits.D. CLS (Cargo Loading System).3. − Define the average weights for the passengers. LOAD AND TRIM SHEET SOFTWARE 3. crew and trolley. Some specific functions allow to create quickly a new cabin layout: utilization of the pitch. cargo and fuel loading on the aircraft weight and CG position. 194 Getting to Grips with Aircraft Weight and Balance . Moreover.WEIGHT AND BALANCE ENGINEERING D. cabin attendant seats. The cabin layout describes all the main deck’s characteristics that affect the aircraft CG position: passenger seats. the user can visualize or create a cabin layout thanks to a graphical interface. − Productions of the Load and Trim sheet and of the AHM 050 document. With those users entries and with the aircraft data. additional possibilities are also offered: − Calculation and production of a Load and Trim sheet for training flights (noncommercial flights). copy of the seats when the left and the right side of the cabin are identical. LOAD AND TRIM SHEET SOFTWARE 3. − Production of data files for the LPC Weight&Balance module (see paragraph “Less Paper in the Cockpit” in part D). the LTS carries out the following tasks: − Calculation of the influence of passengers. galleys and the aircraft section. Cabin layout: Through the cabin layout frame. − Saving and storage of documents for history and follow-up.4. − Calculation of the operational margins (to consider the different errors and assumptions made during a CG determination). lavatories. 5. Getting to Grips with Aircraft Weight and Balance 195 WEIGHT AND BALANCE ENGINEERING .D. LOAD AND TRIM SHEET SOFTWARE 3. − DOW weight used for initial data inaccuracy determination − Passenger weight standard deviation − In flight cabin movements. Some inaccuracy sources may be canceled such as − Passenger distribution − Cargo distribution − Inaccuracy due to CG computation method These inaccuracies may be canceled in case of CG determination using an EDP system. Operational margins customization The LTS software enables to customize certain assumptions used for the operational margins. ............................ 210 4......................... Responsibility..............................................1...........3........... 201 1.................... Perishable goods ................................................................. Live animals and perishable goods...................... Special Loading .......1... 250 2......................... 243 1............................................ 250 2...............................................................................4.................................................................................................................................................. Identification.......... 206 3..................... General ................................... 201 1...... Live animals transportation .......................... 210 4...... 246 2.......................................................................... 256 2.......................................................................... Aircraft acceleration ... Documents.......................1............................ Regulation...................2.................. 225 6.................... References........................2........ 201 1........... Aircraft Weight... Load control qualification....... Preparation before loading ..................... Passenger weight ........................................................... 216 4................. 241 1...............2...........................3.2...................... 205 2.. 249 2....................1.................................................. 207 3..... 225 6....................... Stability on ground – Tipping.. Introduction .......................................... 249 2....... Generalities....................9............................................................................................................... Special shipments ............................................ Structural limitations and floor panel limitations........... Load control....................10............................7...........5......................................................................................................................... On loading ................................ 241 1........................................................................................................................................................................ LOAD AND TRIM SHEET SOFTWARE LOADING OPERATIONS A..................... 241 1..............................................2................................................................ 223 6............................................... 218 5................... Load control organization and responsibilities ................................................ Marking and labeling ............................................................................................. 259 196 Getting to Grips with Aircraft Weight and Balance ...4...................................................................................................................3................................ 215 4...............................................8............................ Dangerous goods .... Packing ....................... Off loading .............................. 217 5............................ Aircraft Weighing... Loading Limitations................................................................1.......................................... 204 2.................................................... Tie-down computation..........1.... 225 6.....................................................................WEIGHT AND BALANCE ENGINEERING D......................................................................................... Handling and loading ........................................................................................................... 254 2..... 207 3........................... 218 5.......................... Opening/Closing the doors......................................................... Definitions ..................... Loading constraints ...............2............................................................................. 207 4............... 255 2..1........ 249 2........................................................................1................................................................. 205 2..................................................... 249 2....... Survey........................ 201 1................................................6........................................ Securing of loads.......................................................... 258 2.....................................................................................................2..................... Loading Generalities...................2............................................3............................................................................................................................................. Classification... 227 B..................3.................................................... Loading Operations ........................................................................ ............................ Load Information Codes ................... 274 4.............. Introduction ....................... 263 1.. Codes used for loads requiring special attention .................. ULD Load volume codes ...............................3.......................... 269 3................................3.............. 263 1.......................... Manual loadsheet....................................... 280 5.............................. 263 1................ Manual LIR 266 2............................................................................................ 264 2......1................................................. 280 5...................................... EDP Loadsheet........... Loading Instruction / Report (LIR)......2......................1................................ 263 1...............................2................................1........... EDP balance calculation methods 288 Getting to Grips with Aircraft Weight and Balance 197 LOADING OPERATIONS .... 278 4...... 271 4................................................ 280 5.....................................3.................................................................................................................. Introduction 265 2...........................................................................4............................ Container/Pallet distribution message (CPM) .........................1..................................................... Manual balance calculation method ................. Introduction .......... Operational Loading Documents ....... ACARS loadsheet .... Load and volume information codes .............................2...................................................................... 265 2.........................................................................2.............. 273 4..................................3... 279 5................... EDP LIR........................................................... 273 4................................................................... Balance calculation methods .....................LOADING OPERATIONS C.... Loadsheet..................... . Getting to Grips with Aircraft Weight and Balance 199 LOADING OPERATIONS . The following chapter details the loading constraints and the necessary organization to fulfil them. The first step before ensuring the aircraft loading is correct is to determine with the necessary accuracy the empty aircraft weight and corresponding CG position. it is necessary to prepare the shipment. Detailed definitions of these limitations are proposed in this chapter. shunting or bumping shocks. Indeed. Air transport has another advantage that can be very useful for cargo such as perishable goods or live animals: its rapidity.A. These limitations are certified by airworthiness authorities. the quantity and distribution of load transported have an influence on the fuselage deformation. In addition to their natural contortion in flight. The shipment must be checked and pre-packed before loading. is probably the smoothest method of carrying cargo. Airbus has defined structural loading limitations that the operator must respect. with no vibration. which must follow some strict rules to ensure passenger. LOADING GENERALITIES LOADING GENERALITIES INTRODUCTION During aircraft preparation before a flight the aircraft loading process is one of the key steps. loads and aircraft safety and security. Therefore. then the determination of the average passenger weight is also important for the loaded aircraft weight determination. air journey. Aircraft have a flexible structure. To ensure an adequate loading and a safe air transport. Air transport is not more risky than other ways of transport. . Nevertheless. particularly special goods such as dangerous goods.A. Loading constraints The main constraints an airline has to face for loading are the following: Safety must be insured during the whole flight whatever goods are transported.2. − The whole shipment must arrive in good condition at destination airport. airlines used to issue manual loadsheets. perishable cargo and live animals. − Loading and unloading must be done at the right place: any mistake concerning the location of the shipment in the aircraft or. responsibilities inside the organization remain comparable.1. Recommendations are provided in IATA AHM part 590. LOADING GENERALITIES A. − − 1. To meet the above objectives and in the interest of flight safety. LOAD CONTROL 1. LOADING GENERALITIES 1. above all. Getting to Grips with Aircraft Weight and Balance 201 LOADING OPERATIONS . airlines have to set up an organization for an efficient load control and ensure a high level of proficiency of all staff engaged in load control work. EDP (Electronic Data Processing) systems are widely used. its destination could engender extra expenses and be very detrimental to the image of the airline. leading to different working organizations. Short time for loading: airlines want to have the aircraft ground time as short as possible in order to respect schedules if an operational irregularity occurred and to make more profit increasing the aircraft utilization. Nowadays. Load control organization and responsibilities Load control is a procedure ensuring that: − Aircraft center of gravity will remain within limits during the whole flight − Aircraft weight limitations are not exceeded − Aircraft is loaded in accordance with the airline’s regulation − Information on the loadsheet reflects the actual load on the aircraft A few years ago. LOADING OPERATIONS A. The main tasks are to: − Collect the relevant Dry Operating Weight / Index of the aircraft − Fill out the number of passengers according to booking information − Transfer the Loading Information (LIR) into the loadsheet. baggage. and after completion. Manual loadsheet The load control organization shall be based. LOADING GENERALITIES 1. − Collect estimated fuel figures from the dispatch and fill out the loadsheet − Enter the transit load data from incoming loadmessage (LDM) − Ensure that the total traffic load does not exceed the allowed traffic load − Ensure that the center of gravity will not exceed the operational limits b) Function 2 : Loading supervisor / loading agent / C2 … (Ramp handling) The loading supervisor carries out the aircraft loading or supervises the aircraft loading when it is subcontracted to a handling company. transit load from incoming LDM/CPM) − Plan load for total flight and ensure that hold capacities and different limitations are not exceeded and center of gravity remains within limits − Plan special loads according to restrictions. maximum quantities. He must ensure that the loading is done in accordance with the LIR. The responsibilities of the load planner are to: − Collect all data relating to the load for a specific flight (Cargo. He has to: − Obtain the Loading Information (LIR) − Assemble the load and necessary equipment − Off-load disembarking deadload and dispatch it as fast as possible − Ensure ULD’s are serviceable and secure − Ensure ULD’s are correctly tagged − Ensure correct lashing and spreading − Check that dangerous goods are correctly stowed − Check that security lockers procedures are followed − Confirm the loading or advise the Load controller / Loadsheet agent of any deviation from the Loading Instructions − Sign the Loading Report (LIR) 202 Getting to Grips with Aircraft Weight and Balance . at every station. and then to prepare the loadsheet. according to the information collected from the passenger and cargo departments. confirms the loading or advise the Load control Supervisor or loadsheet agent of any deviation from the initial loading instruction (Loading Report).2. mail.1. The loading supervisor is responsible for the following tasks. separation and segregation requirements − Consider the effect of the center of gravity on fuel consumption − Issue the Loading Instruction Report (LIR) The loadsheet agent has to prepare the loadsheet. on three functions to ensure the compatibility of all figures on the loadsheet with the actual loading of the aircraft: a) Function 1 : Load planner and loadsheet agent / Load controller / D1 … The main task of this agent is to issue loading instructions (LIR) for people in charge of the loading. A. LOADING GENERALITIES c) Function 3 : Load control supervisor / Dispatcher / Red cap / D3 … The Load control supervisor is the responsible agent for the check of the loadsheet against the final loading report, fueling order and actual number of passengers in the cabin. He has to organize as well the turnaround and is in contact with the crew. The main responsibilities of the Load control supervisor are to: − Inform all parties of the aircraft position and estimated time of arrival on ramp − Check that the loading agent received the LIR and that relevant equipment is correctly planned and positioned − Ensure availability of passenger handling equipment − Ensure that passenger handling personnel is briefed − Confirm passenger boarding time with the authorities − Ensure liaison with crews, both cockpit and cabin − Collect the Loading Report (LIR) from the loading supervisor, and check the loading is in accordance with the LIR − Collect final fuel information from the fueling order − Establish the final loadsheet: ) Update number of passengers according to passenger boarding information at the gate ) Enter exact deadload from the Loading Report (LIR) ) Enter exact amount of fuel from the fueling order ) Ensure that the total traffic load does not exceed the allowed traffic load ) Ensure that the center of gravity will not exceed the operational limits ) Enter last minute changes and inform the flight crew ) Sign the loadsheet and give a copy to the crew (or send it by ACARS) − Check that aircraft documents are on board (Loadsheet, Trim sheet, NOTOC) − Release the aircraft − Send the LDM/CPM to the next station (Loadmessage/Cargo Pallet message) − Store documents in the station’s flight file These three functions must be performed by at least two agents to minimize the risk of mistake and ensure a high safety level. The same person can cumulate, as an example, function 1 and function 3. Getting to Grips with Aircraft Weight and Balance 203 LOADING OPERATIONS LOADING OPERATIONS A. LOADING GENERALITIES 1.2.2. EDP loadsheet In case of EDP (Electronic Data Processing) loadsheet, the responsibility for correct loadsheet and trim data must be shared and clearly identified due to the various operational possibilities (decentralized input of data, decentralized loadsheet issuance, LMC…). The above three functions still exist, but can be decentralized. As an example, Load planning and loadsheet can be prepared at the airline’s base (function 1), whereas loading (function 2) and Load control supervision (function 3) is done at the station. 1.3. Load control qualification The carrier is responsible for its shipment. In order to achieve an acceptable level of standardization and proficiency, minimum requirements shall be recognized in the training of carriers or handling companies’ personnel involved in load control functions. The carrier has the responsibility to: − evaluate and approve the handling company’s training program or subject the personnel involved to a single or periodical qualification tests − Obtain a list of qualified personnel for a given aircraft type 204 Getting to Grips with Aircraft Weight and Balance A. LOADING GENERALITIES 2. AIRCRAFT WEIGHT 2.1. Regulation The purpose of this chapter is to present what is required by the authorities concerning aircraft weighing. The following part will present how the weighing is performed. For more detailed information on aircraft weighing please report to JAR-OPS 1 Subpart J – Mass and Balance. (Paragraph 1.605 and appendix 1 to JAR-OPS 1.605) or/and to FAA Advisory circular 120-27A. 2.1.1. General information: In order to elaborate a proper weight and balance document prior to a flight, the weight of the aircraft (as well as its center of gravity) has to be determined. This weight is first determined by the aircraft manufacturer and is found in the Weight and Balance Manual (Chapter 2.00: Weighing Report). It is the Operating Empty Weight in the Airbus weighing report, it may be named Basic Weight in some other weighing reports. From this Operating Empty Weight/Basic Weight the operator can define the aircraft Dry Operating Weight for each aircraft flight. During its operational life, the aircraft is going to be modified in different possible ways (new cabin arrangement, Service Bulletin implementation, new equipment…). These modifications are going to have an impact on the weight and the CG of the aircraft and therefore the aircraft as to be weighed on a regular basis. Moreover, the mass and the CG of each aircraft shall be re-established either by weighing or calculation (if the operator is able to provide the necessary justification to prove the validity of the method of calculation chosen), whenever: − the cumulative changes to the dry operating mass exceed ± 0·5% of the maximum landing mass − or the cumulative change in CG position exceeds 0·5% of the mean aerodynamic chord. 2.1.2. Fleet mass and CG position: The FAA and the JAA allow an operator that flies a fleet of the same type of aircraft (same model and configuration) to use an average dry operating weight and CG position for the whole fleet. However, individual aircraft weight and CG have to meet the following tolerances: − The weighed or calculated weight of the aircraft varies by less than ±0.5% of the maximum structural landing weight from the established dry operating fleet mass. − The CG position varies by less than ±0.5% of the mean aerodynamic chord from the fleet CG. If an aircraft does meet these tolerances, it has to be omitted from the fleet. However, in the case where an aircraft falls within the tolerance for the dry operating weight but is out of the CG range, it can still be operated with the fleet average mass but with an individual CG position. Getting to Grips with Aircraft Weight and Balance 205 LOADING OPERATIONS LOADING OPERATIONS A. LOADING GENERALITIES • Fleet values determination: The number of aircraft that have to be weighed varies with the number of aircraft in the operator’s fleet. If ‘n’ is the number of aircraft in the fleet using fleet values, the operator must at least weigh, in the period between two fleet weight evaluations, a certain number of aircraft defined in the Table below: Number of aircraft in the fleet Minimum number of weighing n Less than 3 4–9 10 or more n+3 2 n + 51 10 The interval between two fleet mass evaluations must not exceed 48 months and the airplanes that have not been weighed for the longest time shall be weighed in priority. 2.1.3. Individual weights: An aircraft that does not use fleet values must be weighed every 48 months. 2.2. Aircraft Weighing The weighing of the aircraft can either be done on the aircraft’s wheel or on jacks. 2.2.1. Defueling The first action prior to aircraft weighing is the defueling of the aircraft. In order to do so, the aircraft’s nose is lifted up to bring the aircraft to a zero degree pitch attitude. This is done with the help of the aircraft clinometer located in the refueling panel. Once this is done, defueling can be started. The information used is the information of the FQI. The defueling procedure prior to weighing can be found in the Weight and Balance Manual. When the fuel quantity indicated is equal to zero, this means that all the pumpaple fuel has been removed from the aircraft. Extra fuel can be removed using the water drain. Once this is done the only fuel left on board the aircraft is the undrainable fuel (for quantities, refer to the W&B Manual). Fire services have to be present during the operation and the aircraft must be earthed. 2.2.2. Inventory During the defueling of the aircraft, a complete inventory of the equipment fitted on the aircraft is carried out. This inventory is executed with a pre established check list of the equipment that are supposed to be on board the aircraft for normal operations. This checklist will be useful when calculating the Operating Empty Weight and the associated CG. The missing equipment will be added in the weighing report. 2.2.3. Weighing Weighing has to be performed in a closed hangar. Prior to the aircraft’s positioning in the hangar, the scales have to be set to zero. Once the aircraft is in position, its pitch attitude has to be precisely measured. The weighing can then be performed. 206 Getting to Grips with Aircraft Weight and Balance A. LOADING GENERALITIES 3. PASSENGER WEIGHT 3.1. General In order to complete the Load and Trim Sheet, a standard weight for passengers had to be adopted. These values have been fixed by the authorities. In this paragraph, we will consider aircraft seating more than 30 passengers. (For more information, please refer to the appropriate regulation: JAR-OPS1.620 or FAR 121). It is important to notice that the same rules apply to passenger checked-in baggage. The standard values used in the JAR-OPS for passenger weights are the following (these weights include passenger and carry-on baggage): All flights except holiday charters Holiday charters Children 84 kg 76 kg 35 kg However, if for some reason the operator considers that the standard weights do not apply to the routes he operates, he has the possibility of setting his own standard weights. According to the JAR-OPS1 Subpart J, the procedure is the following: If an operator wishes to use standard mass values other than those contained in the table above, he must advise the Authority of his reasons and gain its approval in advance. He must also submit for approval a detailed weighing survey plan and apply the statistical analysis method given in Appendix 1 to JAR–OPS 1.620(g). After verification and approval by the Authority of the results of the weighing survey, the revised standard mass values are only applicable to that operator. The revised standard mass values can only be used in circumstances consistent with those under which the survey was conducted. Where revised standard masses exceed those in the above table, then such higher values must be used. JAR-OPS 1.620(g) 3.2. Survey The methods necessary to revise the standard weights are described in appendix 1 to JAR-OPS 1.620(g) with reference to the IEM to JAR-OPS 1.620(g) and IEM to Appendix 1 to JAR-OPS 1.620(g). The purpose of this paragraph is to give the reader a quick overview of the methods used. In order to change the standard values, the operator must conduct a survey. This survey has to follow a certain number of rules. The average mass of passengers and their hand baggage is determined by weighing random samples of passengers representative of the type of operation (frequency of flights on various routes, in/outbound flights, applicable season, seat capacity of the aircraft…) All adult revised standard mass values must be based on a male/female ratio of 80/20 in respect of all flights except holiday charters which are 50/50. It is possible to use a different male/female ratio if it is representative of the activity (refer to regulation, in particular: IEM to Appendix 1 to JAR-OPS 1.620(g): Guidance on passenger weighing surveys) Getting to Grips with Aircraft Weight and Balance 207 LOADING OPERATIONS LOADING GENERALITIES 3. σ ' : the ‘a priori’ estimates of the average passenger mass and the standard deviation. then er ' will be 1 in the above formula.96 is the value from the Gaussian distribution for 95% significance level of the resulting confidence interval. This standard deviation value is also used for calculating the standard passenger mass. σ : the true values of the average passenger mass and standard deviation. For example. Nb of pax Standard Deviation σ Pax average Weight µ Pax weight The number of passengers to weigh must be of at least the greatest of: − A number of passengers calculated from a pilot sample. NOTE: The allowed relative confidence range specifies the accuracy to be achieved when estimating the true mean. mean and standard deviation. if it is proposed to estimate the true mean to within ± 1%. i.e. As a consequence. i.2. Statistical Analysis Passenger weight follows a Gaussian distribution that can be studied using statistical methods. for the parameters of mass distribution. values resulting from an earlier survey. using normal statistical procedures and based on a relative confidence range (accuracy) of 1% for all adult (in order to find this number of passenger. which are needed to determine the current sample size.LOADING OPERATIONS A. (for aircraft of over 40 seats) The precision of a sample estimate is calculated for 95% reliability or ‘significance’. 1. there is a 95% probability that the true value falls within the specified confidence interval around the estimated value. two cases have to be distinguished: − µ.e. − µ’.1. The sample size can then be calculated using the following formula: 1.96 * σ '*100 n≥ er '*µ ' 2 where: n is the number of passengers to be weighed (sample size) er ' is the allowed relative confidence range (accuracy) for the estimate of µ by (see also equation in paragraph 3). 208 Getting to Grips with Aircraft Weight and Balance . which are unknown and which are to be estimated by weighing passenger samples.e. i. a previous survey is necessary) − 2000 passengers. 2. _ x j − x ∑ j =1 n −1 n 2 Standard deviation: σ = 3. This means that with 95% probability. LOADING GENERALITIES • Calculation of average mass and standard deviation.96 * σ *100 n *µ whereby er should not exceed 1%.96 * σ n Getting to Grips with Aircraft Weight and Balance 209 LOADING OPERATIONS .A. the true average mass µ lies within the interval: µ± 1. This is done using the formula: er = 1. The accuracy (confidence range) which can be ascribed to the sample mean as an indicator of the true mean is a function of the standard deviation of the sample which has to be checked after the sample has been evaluated. The result of this calculation gives the relative accuracy of the estimate of µ at the 95% significance level. Accuracy of the sample mean.2. Arithmetic mean of sample: µ = ∑x j =1 n j n Where x j are the mass values of individual passengers (sampling units). 1. which reduces the airline’s expenses. etc. all the items are stacked without any order. flowers. 4. The destination must be written on a label attached to the sack. The different configurations for each aircraft are described in the “Cargo systems” part of this manual. air journey.1. Both pallets and containers are locked in the aircraft using latches and end-stops. LOADING GENERALITIES 4. Air transport has another advantage that can be very useful for cargo such as perishable goods or live animals: its rapidity. ULDs are loaded into the aircraft thanks to specialized ground equipment. Specific packages are required for specific cargo such as live animals. Collection sacks or nets are used to facilitate handling of small items. To ensure an adequate loading and a safe air transport. In bulk compartments. dangerous goods. Since ULDs must be pre-packed. LOADING OPERATIONS 4. Parcels that are in the same cover bag must be off-loaded at the same airport. The shipment must be checked and pre-packed before loading.1. is probably the smoothest method of carrying cargo. It allows decreasing the station time for each aircraft. Preparation before loading 4. Compartments equipped with the Cargo Loading System are filled with ULDs. 4. which is easier and faster to load.2. shunting or bumping shocks. most of the job is done before and after the flight. it is necessary to prepare the shipment. ULDs can be either pallets or containers. Certified containers protect the aircraft systems and structure.1. 210 Getting to Grips with Aircraft Weight and Balance . Not all the items can be transported in collection sacks: − Radioactive loads must not be put in collection sacks because of the minimum distances imposed between two radioactive loads − Cargo and mail must not be in the same cover bag. wet cargo. Non certified containers are sometimes used to take several loads into large pre-packaged units.LOADING OPERATIONS A.1. They are expensive and delicate units because of the materials used to make it. Generalities Air transport is not more risky than other ways of transport. ULD / Bulk Airbus aircraft have different configurations of compartments: they can be loaded either with bulk or with ULDs (Unit Load Devices).3. Indeed. Packing Items should not be loaded in the aircraft if they are not properly packed. with no vibration. They are called “cover bags”. These ULDs allow to group items into larger units. 4.1. small. coffins containing human remains must be loaded in a horizontal position. light or weak items on the top. ♦ Handling and loading of human remains must be done with respect. LOADING GENERALITIES Each package is then packed itself into a ULD when the aircraft is equipped. Special loads Dangerous and perishable goods. weight and strength) − Big or heavy items must be on the bottom. general rules must be applied: − When packages are loaded in a container. − Leave as few spaces as possible between two items − The load must be evenly distributed in the ULD. it is necessary to visualize the whole container load before packing (nature. they must be wrapped with specific packages to minimize the risk of accident and/or incident. The nets retain the load. When they are allowed for transport by air. Moreover. For a safe cargo transport. Some dangerous goods are even forbidden for transport by air. Thanks to labels affixed to each package. Here are some rules concerning special goods transportation. especially to packages containing special goods. − Spreader boards could be used for high density items − If the package moves in the ULD or if the load is very heavy. Heavy items must not be concentrated on a small area in the center of the pallet and/or container because of the risk of dishing. human remains must be kept far away from other shipments such as food or some animals (dogs for example). 4. Getting to Grips with Aircraft Weight and Balance 211 LOADING OPERATIONS . ♦ The security of valuable cargo must be ensured during the whole journey. ♦ Staff concerned by transportation of special loads must be aware of the requirements of such a cargo.A. ♦ Not all the dangerous goods can be transported in passenger aircraft because of the obvious risk they engender for the safety of passengers. valuable cargo. two rules have a very big importance: they must not be exposed to extreme temperatures and they should be loaded in the aircraft as late as possible. form. then the package should be tied down − Packages loaded on open pallets should be stacked so that the whole load is stable (interlocking layers). live animals. never in a vertical position. ♦ For live animals. Once they are loaded. loading staff is able to identify the content of the package. ♦ To arrive at their destination in good condition. human remains and urgent shipments are considered as special cargo. Their weight is then entered on the tag described hereafter. and special requirements apply to them. perishable goods require specific temperatures and relative humidity that depend on the good transported. Ventilation and heating systems are greatly recommended. cargo pallets and containers are weighed. 4. like dangerous goods. hatching eggs and unexposed films − Live animals must be loaded in close proximity of neither foodstuffs nor human remains − Live animals and hatching eggs must not be loaded in close proximity of dry ice − Live animals should be separated from laboratory animals − Animals that are natural enemies such as cats and dogs should not be loaded in sight. live animals and perishable goods. 5 and 8 shall not be loaded in close proximity of dangerous goods from class 1 − Dangerous goods from class 7 must be separated from animals. 212 Getting to Grips with Aircraft Weight and Balance . Incompatibilities Some shipments are particularly restrictive to transport. Special requirements concerning transportation of such goods are developed in other parts of this manual (refer to “DANGEROUS GOODS TRANSPORTATION” and “LIVE ANIMALS & PERISHABLE GOODS TRANSPORTATION”). sound. 3.1. LOADING GENERALITIES 4.LOADING OPERATIONS A.5. The following table from IATA AHM 645 sums up the incompatibilities between different shipment types: Here are general rules that can be extracted from this document: − Dangerous goods from classes 2. smell or reach of each other − Foodstuffs must not be loaded in close proximity of human remains…. live animals or perishable cargo are provided in the corresponding sections. labels used to indicate the presence of dangerous goods. A tag must be completed. Labelling. Getting to Grips with Aircraft Weight and Balance 213 LOADING OPERATIONS . even for empty ULDs. LOADING GENERALITIES 4.A. on a fixed side of the container or on the net of the pallet. tagging Each package or collection sack is labelled to indicate the destination and the category of load it contains.6.1. The tag must be easily readable: it must be at eye level. the red line must appear on the tag. Its shape and colors are standardized: Size: A5 (148 x 210 mm) Color: Black letters with: BAGGAGE A red slash on a white background* DANGEROUS GOODS Red hatching surrounding the tag UNSERVICEABLE UNITS Orange background OTHER LOAD White background * Whenever an ULD contains baggage. Specific labels are used for special loads. Here are some codes used to identify which category a load belongs to: B → Baggage C → Cargo (including special loads) M → Mail Unit Load Devices (ULDs) must be tagged so that the loader is able to identify loads in the containers and/or pallets. LOADING OPERATIONS A. 214 Getting to Grips with Aircraft Weight and Balance . LOADING GENERALITIES ULD tag example Delete the wrong word ALF2503AF ULD code Airport where the ULD must be unpacked (San Francisco) Separation between NET and TARE weight mandatory when ULDs are transferred between carriers SFO 1500 100 1600 CDG JFK AF5 025 UA2 053 31P 22P First leg information Second leg information C = Cargo C AVI Presence of special loads (refer to “Operational loading documents” for the codes) Some operators use an electronic system to read ULD tags. A bar code that contains all the previous information is then shown on the form. it is necessary to ensure that the door protector nets are installed and secured. electrically). In presence of wind. No equipment must obstruct the passage of the door. whereas the bulk compartment door (compartment 5) opens to the inside. The maximum wind speed allowed to have the door opened is given in the Cargo Loading System Manual. No special training is required for manual doors. Opening/Closing the doors There are two different types of cargo doors: some open manually and others automatically (hydraulically. Ground staff operates cargo doors. so that ground staff can open and close them. LOADING GENERALITIES 4. Getting to Grips with Aircraft Weight and Balance 215 LOADING OPERATIONS . whereas only qualified staff is allowed to open hydraulic or electric doors. Airbus provides a detailed description of the doors and the way to operate them in the Weight & Balance Manual. Bulk Cargo door FWD or AFT Cargo door Before closing the bulk compartment door (compartment 5). the loading supervisor must ensure that doors are closed and secured. the forward and aft cargo compartments doors open to the outside. After on-loading and off-loading.A. special care must be taken before opening the doors or when the doors are already opened. In Airbus aircraft.2. On loading 4. ULDs can be either pushed into position or progressed by powered rollers. etc.3. In case of failure. Cargo Loading System (CLS) The Cargo Loading System is installed as basic in the aft and forward cargo compartments of all the Airbus aircraft except the A318. The bulk compartment is divided into sections thanks to nets. − Use mechanical handling aids to handle heavy items 4. then the package should be tied down. LOADING GENERALITIES 4. Most of them are common with the loading of items into ULDs. If one limit is exceeded. otherwise CLS latches and or ULDs could be damaged − No staff must be in front of an ULD when it is pushed or driven into position − All the stops. A few rules must be respected to load ULDs: − Each ULD must go to the position indicated by the Loading Instructions prepared by the load planner − All obstacles have to be removed (including floor locks and side restraints) to allow the ULD to go into its position.2. the loading agent has to ensure that the floor. but it may be useful to remind them: − Heavy items at the bottom − Use the maximum available volume − The load must be evenly distributed in the net section − Follow specific instructions shown on the labels and place the articles so that the labels are easily visible − Respect weight limitations of the aircraft given in the Weight and Balance Manual.LOADING OPERATIONS A. A319. Bulk This way of transporting loads is used in cargo holds not equipped with a Cargo Loading System (CLS). pieces with sharp points or edges. Several precautions must be taken for loading. Before being loaded in the aircraft. refer to the “Limitations” section of the Weight and Balance Manual of the aircraft to determine the weight restriction engendered by the failure. The positions where ULDs must be loaded are indicated in the Loading Instructions/Report form (refer to “Operational Loading Documents”). locks and restraints necessary to fix the ULD in position must be used. use spreader boards. A320 and A321 where it is optional. Most Airbus types have at least one bulk compartment at the rear.3. ULDs are filled as described above. ice and water. the loading agent has to check that there is no leaking or damaged package. Before loading bulk load. The Cargo Loading System makes the loading easier for loading staff: once in the aircraft. This check is absolutely necessary when transporting live animals or wet cargo. They must be cleared of snow. every leaking or damaged package must not be loaded.1. − If a package is likely to damage other packages (heavy item. named compartment 5. it is necessary to ensure that the separation nets are properly secured. and the bulkhead are in good conditions.). 216 Getting to Grips with Aircraft Weight and Balance . Moreover. Before loading. the walls.3. LOADING GENERALITIES Once all the ULDs are loaded into the aircraft. There is a priority between different sorts of baggage: Code Priority Description TB 1 Baggage for transfer to various connecting flights HB 1 Group of baggage (ULD) that must be transshipped to the same connecting flight HTB 1 Group of baggage (ULD) that must be transshipped to various connecting flights FB 2 First class baggage and/or priority handled baggage B 3 Baggage (no specification) 2) Cargo 3) Mail In case of a multi-sector flight. etc. An inspection of the shipment allows determining the presence of damaged or leaking packages.3.A.) − The package must not contain liquid. He checks that they have been loaded in compliance with the regulations and if so. baggage or mail are loaded on seats in the passenger cabin provided that several constraints are respected: − Weight limitations must not be exceeded − Safety rules must be respected (not next to emergency exits. In case of leakage. no emergency equipment obstructed. live animal or smelling cargo − The package must be tied down and covered − The seat should be protected from possible damage 4. and any irregularity or discrepancy with the document must be reported.3.4. even before passengers disembark when it is possible. the source must be identified and the compartment in which leaking goods were transported must be inspected for contamination. Off loading The items must be off-loaded in descending order of priority: 1) Baggage must always be off-loaded first. when there is not enough space in the cargo holds or for some specific cargo items. 4. at a transit station. Loading agents must check cargo and mail against these instructions. the load planner has to prepare off-loading instructions (LIR(1)) from the incoming messages (CPM/LDM(1)). the responsible loading supervisor checks the loading. small items of cargo. and that transit shipment is at the right place. he fills the Loading Report in and signs it (refer to “Operational Loading Documents”). (1) Refer to “Operational loading documents” paragraph Getting to Grips with Aircraft Weight and Balance 217 LOADING OPERATIONS . so that passengers are not delayed by waiting for their baggage. Seats Occupied by Cargo (SOC) Sometimes. at transit airport loading agents have to check all that must be off-loaded is offloaded. 1.2. Structural limitations a) Running (Linear) Load Limitation • Definition: The running load limitation is the maximum load acceptable on any given fuselage length of an aircraft floor. In addition to their natural contortion in flight.1. They follow IATA AHM 513 recommendations. the repartition and the quantity of load transported have an influence on the fuselage deformation.LOADING OPERATIONS A.4 Max weight = 2000 x 0.2 m Flight direction 870 kg Running load = 870 = 2175 kg/m > 2000 kg/m 0.1. LOADING GENERALITIES 5.2 m Running load exceeded 218 Getting to Grips with Aircraft Weight and Balance . These limitations are certified by airworthiness authorities and can be found in the “Limitations” section of the Weight and Balance Manual. 5. • Unit: kg/m or lb/ft Running Load = Weight of the piece W = Length of the piece in the flight direction L The length to take into account is the length of the contact points on the floor.2 m 0.2 = 2 400 kg > 870 kg Running load not exceeded Example 2 1. LOADING LIMITATIONS 5.1. Structural limitations and floor panel limitations 5. • Example: Let’s assume a Maximum Running Load of 2000 kg/m Example 1 Flight direction 870 = 725 kg/m < 2000 kg/m 1. Airbus has defined structural loading limitations that the operator must respect. Introduction Aircraft have a flexible structure. Therefore.2 870 kg Floor 1.4 = 800 kg < 870 kg Floor 0.2 m Running load = Max weight = 2000 x 1. Note: The Compartment Load Limitation is called “Cumulative load” limitation in the Airbus Weight and Balance manuals and it concerns the complete forward or aft hold or the aircraft.1 m 870 kg 0. floor panels and frames). This limitation applies to the whole load located in a given compartment.5 m Area load = 870 = 1450 kg/m < 2000 kg/m 0. • Unit: kg or lb Getting to Grips with Aircraft Weight and Balance 219 LOADING OPERATIONS .A.6 = 1 200 kg > 870 kg 1. LOADING GENERALITIES b) Area load limitation • Definition: The area load limitation is the maximum load acceptable on any surface unit of an aircraft floor. It prevents the load from exceeding the capability of the aircraft structure (floor beams. • Example: Let’s assume a Maximum Area Load of 2000 kg/m2 The following rectangular load is laying onto four pieces in direct contact with the floor. Contour area (0. The surface used for the calculation of the area load is represented by the external green contour.1 m 0. Note: The Area Load Limitation is called “Uniformly distributed load” limitation in the Airbus Weight and Balance manuals.2 m 4 contact points Area load not exceeded c) Compartment Load Limitation • Definition: The compartment load limitation is the maximum load acceptable in an entire compartment.6 Max weight = 2000 x 0.6m2) 0. floor posts. • Unit: kg/m2 or lb/ft2 Area Load = Weight of the piece W = Contour Area S The contour area is the external contour of the contact points on the floor. Note: The Cumulative Load Limitation is called “Fuselage Shear load” limitation in the Airbus Weight and Balance manuals.LOADING OPERATIONS A. 220 Getting to Grips with Aircraft Weight and Balance . LOADING GENERALITIES d) Cumulative Load Limitation • Definition: The cumulative load limitation is the maximum weight that can be carried forward or aft of a given section. This limitation prevents the weight loaded in the forward and aft fuselage sections to exceed the capability of the frames and skin stringers. 24 Weight and balance manual extract The total payload weight applied on the main deck and the lower deck forward of frame 40 must not exceed 18 tons when the ZFWCG is 24%. • • Unit: kg or lb Example: Fuselage shear load forward of frame 40. • Example: Let’s assume a Maximum Contact Load of 2000 kg/m2 The following rectangular load is laying onto two pieces in direct contact with the floor. Note: The Contact Load Limitation is called “Local load” limitation in the Airbus Weight and Balance manuals. Getting to Grips with Aircraft Weight and Balance 221 LOADING OPERATIONS . honey comb sandwich panels).3.2 m 870 kg 0.2 = 400 kg < 870 kg 1.2 Max weight = 2000 x 0. The area used for the calculation of the contact load is represented by the green contours.2 m 0. Floor panel limitations a) Contact load limitation • Definition: The contact load limitation is the maximum load acceptable in direct contact with the aircraft floor per surface unit.1.2 m²) Contact load exceeded b) Point Load Limitation • Definition: The point load limitation represents the resistance to puncture by a heavy load bearing onto a very small surface of the floor panels. • Unit: kg/cm2 or lb/ft2 • Examples: To avoid floor panel punctures. This limitation is used to prevent the load in direct contact with the floor from exceeding the capability of the horizontal floor panels (metal sheet. 0. Note: The Point Load Limitation is called “Walking load” in the Airbus Weight and Balance manuals. the following elementary handling precautions are recommended.A.2 m Surface in direct contact with the floor (0. LOADING GENERALITIES 5.5 m Contact load = 870 = 4350 kg/m > 2000 kg/m 0. • Unit: kg/m2 or lb/ft2 Contact Load = Weight of the piece W = Contact Area S The contact area is the surface in direct contact with the floor. 35 500 Contact load = = 3125 kg/m2 0.1.48 Running load = 0.2 m 1.16 2 0.LOADING OPERATIONS A.2 m Note: Spreader’s weight = 20 kg 222 Getting to Grips with Aircraft Weight and Balance . place a floor protector device beneath the pinch bar (plank.4.4 500 = 1429 kg/m2 0. m 5 0. It allows increasing either the length of the piece or the area in direct contact with the floor.2 m 0. Spreader floor A spreader floor enables to transport loads whose weight exceeds one of the previous limitations (running load. area load or contact load). LOADING GENERALITIES − Never lay a heavy package on an edge or a corner: − When using a pinch bar. Example : Max running load = 500 kg/m Max area Load = 1000 kg/m2 Max contact load = 2000 kg/m2 0.7 m Without spreader floor Running load = Area load = 500 = 1250 kg/m 0. piece of wood): 5.6 500 + 20 Contact load = = 1084 kg/m2 0.2 500 + 20 Area load = = 867 kg/m2 0. m With spreader floor 500 + 20 = 434 kg/m 1. b) Loading/Off-loading Loading operations should start in the forward compartment and then in the aft ones. To help the operator establishing its own recommendations for loading and off-loading. and pay a particular attention to the distribution of the transit load on multi-sector flights. 5. the load planner must allocate a sufficient load ahead of the aircraft center of gravity.2.2. the operator can simulate different critical scenarios and evaluate the risk of tipping of its aircraft in these configurations. the tip up CG position (max aft CG position) is provided in the limitation section of the Weight & Balance Manual (refer to the graph “Aircraft stability on wheels”). LOADING GENERALITIES 5.1. Therefore. Precautions a) Load planning During load planning. The same sequence applies for the galleys.A. while offloading operations should start in the aft compartment and then the forward ones.2. Introduction During on-loading and off-loading operations. Thus. Getting to Grips with Aircraft Weight and Balance 223 LOADING OPERATIONS . an aft center of gravity position may lead to a tail tipping of the aircraft.2. whereas passenger distribution must not be considered to secure ground stability. specific precautions should be considered to avoid this kind of critical situation. Stability on ground – Tipping 5. LOADING GENERALITIES c) Maximum wind for stability on wheels Due to the large surface of the wings. 224 Getting to Grips with Aircraft Weight and Balance . as shown in the example. It can help the operator establishing its own recommendations for loading and off-loading rules in windy conditions. enables to determine the maximum allowable wind for a given aircraft weight and center of gravity position.LOADING OPERATIONS A. provided in the limitation chapter of the weight and balance manual. The following graph. the wind can affect the stability of the aircraft on ground by providing a lift force ahead of the center of gravity and as a consequence a rolling moment around the main landing gear group or the center gear if any. the net section or the ULD.2. Note : the 150 kg figure is the value recommended in the AHM document.2. except on single sector flights when the compartments or net section is volumetrically full. shape or density may constitute a hazard. damaging the structure of the aircraft or crashing other cargo loads. SECURING OF LOADS 6. Pieces weighing 150 kg or more. Restraint can be achieved by filling volumetrically the compartment. nevertheless each individual operator may define a lower value for Heavy Items definition. LOADING GENERALITIES 6. Introduction As per IATA AHM 311. As a consequence. all individual items of load.A. or by tie-down. Influence on cargo items Anytime an aircraft accelerates. forces are generated on each cargo item. Note: In IATA Airport Handling Manual (AHM) Compartments.1. hazardous or heavy items must be tied-down in order to prevent them from moving. Aircraft acceleration 6. when packed in certified ULDs should be individually tied-down except when the unit is volumetrically full. when loaded as bulk in compartments or net sections should always be tied down. The force generated by the movement of the aircraft depends on the aircraft acceleration and the weight of the piece. 6. decelerates or turns. Getting to Grips with Aircraft Weight and Balance 225 LOADING OPERATIONS . Pieces weighing 150 kg or more. net sections and ULDs are considered to be volumetrically full when they are filled up to three-quarters (75%) of their height. which by their nature. Note 2 : this value is indicated as 80% of the height in Airbus Weight and Balance Manuals.1. shall be restrained. if an item weighing 1000 kg is submitted to a load factor of 1. sideway movements or vertical drops.a = nX. of an item submitted to an acceleration that can be caused by: a speed increase. X axis Z axis M Fz = W= M.M.a = M.ax = nx.g M = mass of the item W = weight of the item = M.g Wa = Apparent weight = n.g aX = item’s acceleration in the X direction FX = Force in the X direction = M.2. LOADING GENERALITIES 6.2.g Wa = n. in a given direction.LOADING OPERATIONS A.M.a FZ = Force in the X direction = M. The operator has to forecast the restraint of heavy items in each direction. Load factor The load factor represents the “apparent weight”. a slow down. Each restraint must resist to the maximum apparent weight in each direction.M.5 in a given direction. the apparent weight of this item is equivalent to the weight of an item with a mass of 1500 kg and no load factor applied.M.g n = Load factor nX = Load factor in the X direction Therefore.g Fx = M. taking into account the maximum admissible load factors published in the limitation chapter of the weight and balance manual of each aircraft type. 226 Getting to Grips with Aircraft Weight and Balance . can not be used for direct tie-down on the cargo floor. Getting to Grips with Aircraft Weight and Balance 227 LOADING OPERATIONS . b) Lashing equipment Different types of equipment can be used for lashing: nets. LOADING GENERALITIES 6. The maximum breaking strength of a single stud fitting is 900 kg (2000 lb). Lashing equipment must indicate permanently the maximum breaking strength. Heavy rings (double stud fittings). c) tie-down fittings Airbus cargo hold floors are equipped with tie-down points enabling quick fastening of small rings only (single stud fittings).3. but for tie-down on pallet’s or container’s rims. The maximum breaking strength for a double stud fitting is 2270 kg (5000 lb). Only equipment for which the breaking strength is ascertained should be used.1 Tie-down equipment a) Breaking strength The breaking strength for a lashing or a tie-down fitting represents the maximum load that the item shall withstand without failure. except when the restraint equipment is part of a pallet or an aircraft compartment (pallet nets and divider nets). cables.1. ropes or straps. Only the tie down points which are not required for net fastening may be used for restraint of packages. 3. Tie-down computation 6.3.A. Tie-down shall ensure restraint in the forward. δ. General tie-down recommendations − − − It is prohibited to tie-down a load with different lashing equipment (straps and ropes as an example). αF. up. Each strap or rope shall make a maximum angle of 30 degrees with the direction of restraint (e.g. UP − − δ FWD LEFT UP L δ R AFT RIGHT α A α B A = Floor angle (Restraint in the AFT direction) α α δ β β β AFT A/L β TOP F/L F = Floor angle (Restraint in the FWD direction) FWD L / R = Wall angle Left / Right (Restraint in the UP direction) Wall angle Left / Right (Restraint in the AFT direction) A L / R= β A/R β F/R F L / R = Wall angle Left / Right (Restraint in the FWD direction) − It is prohibited to use two ropes or straps attached to the same tie-down point and restraining the load in the same direction. A minimum distance between two tie-down points shall be respected (generally 30 cm between two single stud fittings and 50 cm between two double stud fittings). for tie-down in bulk compartments or inside containers. when no other equipment is available.2. βA. aft and up directions is adequately performed except for irregular shape loads and for high CG loads. lateral tie-down is generally covered if tie-down in the forward. αΑ.3. With a standard lashing. Single stud fittings and ropes can be used in case of absolute necessity. LOADING GENERALITIES 6. βF). left and right directions. aft. 228 Getting to Grips with Aircraft Weight and Balance .LOADING OPERATIONS A. attached to 4 tiedown points (2 on each side of the piece in the flight direction).3. For that purpose. Security rope Strap or rope Flight direction Tie-down point 6. Y. This basic pattern solves most of the lashing problems. Left and Up directions.3. the force applied to each tie-down point in any direction must be carefully studied. 1 Forward. it is necessary to consider a reference axis system (X. Forces breakdown In order to compute the number of ropes or straps needed to restrain a load. A security rope may be used to maintain straps in correct position and prevent them from slipping down. Z) in the Forward. 1 Aft). generating two forces: the force F1 is generated by a strap restraining the load in the forward direction. Z F2 F1 X Y Flight direction Tie-down point In the above example.4.A. LOADING GENERALITIES 6. Standard lashing A standard lashing consists into four straps or ropes (2 Up. whereas the force F2 is generated by a strap restraining the load in the up direction.3. two straps are attached to each tie-down point. Getting to Grips with Aircraft Weight and Balance 229 LOADING OPERATIONS . cos(α). Consequently.cos(β) In Y direction Z F1 β F1Y α β Y X F1Y = F1.cos(α). LOADING GENERALITIES • Forward strap: F1 force breakdown In X direction Z F1 α β F1X X Y F1X = F1. for a FORWARD (or AFT) strap.sin(β) In Z direction Z F1 α α F1Z Y X F1Z = F1. the minimum restraint force in each direction can be expressed as follows: F1x = 75% F1 F1y = 43% F1 F1z = 50% F1 230 Getting to Grips with Aircraft Weight and Balance .sin(α) As each strap shall make a maximum angle of 30 degrees with the direction of restraint.LOADING OPERATIONS A. α and β shall be less than 30º. Nevertheless some operators might choose even when applying the recommended 30° to perform the computation with an angle of 45° in order to take into account a margin in case one of the ropes in not correctly tied down. It is counted negative in the aft and right directions. for an UP strap. one decreases the weight that can be restrained by the item. left or up directions. In this case the above force breakdown is F1x = 50% F1. indeed by increasing this angle. one decreases the weight that can be restrained by the item. F2z = 70% F2 Note2: When the force is applied in the forward. In this case the above force breakdown is F2x = 0.A. F2Z = F2. δ shall be less than 30º. it is considered as positive. LOADING GENERALITIES Note : the recommended 30° between the rope or the strap with the main direction of restraint enables a high restrained force in the needed direction. Consequently. indeed by increasing this angle.sin(δ) . F2Y = F2. Nevertheless some operators might choose even when applying the recommended 30° to perform the computation with an angle of 45° in order to take into account a margin in case one of the ropes in not correctly tied down. F2y = 70% F2. F1y = 50% F1. F1z = 70% F1 • Up strap: F2 force breakdown Z F2 F2Z δ F2Y X Y F2X =0 .cos(δ) As each strap shall make a maximum angle of 30 degrees with the direction of restraint. the minimum restraint force in each direction can be expressed as follows: F2x = 0 F2y = 50% F2 F2z = 86% F2 Note : the recommended 30° between the rope or the strap with the main direction of restraint enables a high restrained force in the needed direction. Getting to Grips with Aircraft Weight and Balance 231 LOADING OPERATIONS . and the lashing equipment shall be able to restrain a load equivalent to the piece’s apparent weight: F = nx. In that case. a force F is generated in the forward direction with a magnitude proportional to the aircraft deceleration rate.3. the load would slip forward. the lashing must be done so as to be able to restrain any piece submitted to a load factor of 1.LOADING OPERATIONS A. Moreover. To prevent it from moving in the forward direction. Considering a force F1 of 900 kg. As shown in the following “Weight & Balance Manual” extract.3.W (with W = piece’s weight). Ultimate load a) Example 1 Let’s assume that the previous piece is loaded in the aft cargo hold of an aircraft.69 in the FORWARD direction. a strap is tieddown to a single stud on each side of the load. F1y and F1z as shown previously. 232 Getting to Grips with Aircraft Weight and Balance . as shown below. LOADING GENERALITIES 6. Without restraining system.6. the load factor in the X direction (nx) becomes greater than 1. 1 F1 Y FWD W Z X F2 2 The forces F1 generated by the deceleration at the tie-down point number 1 can be decomposed into three components F1x. COMPARTMENT 3. a sudden deceleration of the aircraft. Maximum load Let’s assume.5. F must be less than 900 kg. the maximum force components at tie-down point number 1 are: F1x max = 75% F1 = 675 kg F1y max = 43% F1 = 387 kg F1z max = 50% F1 = 450 kg 6. as an example. At each tie-down point. each tie-down point (single stud fitting) can withstand a maximum load of 900 kg. Therefore. the maximum load that can be restrained in the forward direction by one strap fastened to two tie-down points (1 and 2) is : Maximum load = Fx max = F1x max + F2x max = 675 kg + 675 kg = 1350 kg The Ultimate Load represents the maximum weight of a piece or a pallet that can be restrained by a lashing equipment in a given direction. the maximum piece’s weight must not exceed 1597 kg due to the breaking strength of the tie-down points.69 = 1597 kg Conclusion: With TWO straps restraining the load in the forward direction. if the piece’s weight is W. 3 and 4) is : Maximum load = Fx max = F1x max + F2x max + F3x max + F4x max = 4 x 675 kg = 2700 kg Ultimate Load = 2700 / 1. the maximum piece’s weight must not exceed 798 kg due to the breaking strength of the tie-down points. the force that has to be restrained by the lashing equipment in the forward direction is : Fx = 1. creating a force of magnitude Fn at each tie-down point n.69 x W The maximum load that can be restrained in the forward direction by two straps fastened to four tie-down points (1. b) Example 2 Let’s assume that the load is now restrained in the forward direction by two strap as shown in the next figure.69 = 798 kg Conclusion : With ONE strap restraining the load in the forward direction.A. LOADING GENERALITIES Therefore. In our example. the ultimate load in the forward direction is : Ultimate load = Maximum Load / Load factor Ultimate Load = 1350 / 1. Note : It is prohibited to use two straps attached to the same tie-down point and restraining the load in the same direction 1 F1 3 F3 Y FWD W Z X 2 F2 4 F4 Each strap is fastened to two tie-down points. Getting to Grips with Aircraft Weight and Balance 233 LOADING OPERATIONS .69 W As shown in the previous paragraph. 2. The force that has to be restrained by the lashing equipment in the forward direction is still: Fx = 1. 2 Up) fastened to 4 single stud fittings (see next figure). Z Fn α β TDn Y X α : angle between the force direction and the floor. it is possible to establish the ultimate load in each direction (Forward. Left. Z STu STA STF TDLF TDLA Tie-down point TDRF STu X TDRA Flight direction Y With: STF = Strap Forward STA = Strap Aft STU = Strap Up TDLF = Tie-down point Left Forward TDLA = Tie-down point Left Aft TDRF = Tie-down point Right Forward TDRA = Tie-down point Right Aft a) Angles definition The force breakdown needs to be calculated for each tie-down point. LOADING GENERALITIES 6. As done previously. 234 Getting to Grips with Aircraft Weight and Balance .7.LOADING OPERATIONS A. Up. Ultimate load for a standard lashing (4 straps) Let’s now consider a standard lashing composed of four straps (1 Forward. Aft. 1 Aft. Note : for the following example we assume that each strap shall make a maximum angle of 30 degrees with the direction of restraint. β : angle between the force direction and the forward direction.3. So for each point the angles α and β need to be defined. Right). Restraint AFT TDLA STA : α = 30°. Restraint FORWARD TDLF STF : α = 30°. Restraint FORWARD TDRF STF : α = 30°. Right Tie Down Points Restraint UP TDRF STU : α = 60°. TDLA STU : α = 60°. TDRA STU : α = 60°.A. Restraint AFT TDRA STA : α = 30°. LOADING GENERALITIES • Left Tie Down Points Restraint UP TDLF STU : α = 60°. β = 90° β = 90° β = 30° Z STu STA STF TDLF TDLA Tie-down point TDRF STu β = 150° X TDRA • Flight direction Y β = 270° β = 270° β = 330° β = 210° Getting to Grips with Aircraft Weight and Balance 235 LOADING OPERATIONS . 0.86 F + 0.0.43 F .43 F FZ UP = 0 86 F FZ AFT = 0 50 F • Right Tie Down Points TDRF : 2 straps : 1 UP and 1 FORWARD Fx UP = 0 Fx FORWARD = 0.86 F FY LEFT = 0.43 F FZ UP = 0 86 F FZ AFT = 0 50 F Note : F being the maximum breaking strength allowed at the tie-down point.5 F FY RIGHT = .5 F FY FORWARD = 0.0.sin(β) FZ = F.0.86 F / nLEFT Ultimate Load UP = FZ / nUP = 5.75 F = .5 F +0.0.0.86 F / nRIGHT Ultimate Load LEFT = FY LEFT / nLEFT = 1.43 F FZ UP = 0 86 F FZ FORWARD = 0 50 F TDRA : 2 straps : 1 UP and 1 AFT Fx UP = 0 Fx AFT = .86 F + 0.5 F + 0.0.0.cos(α).44 F / nUP 236 Getting to Grips with Aircraft Weight and Balance .sin(α) • Left Tie Down Points TDLF : 2 straps : 1 UP and 1 FORWARD Fx UP = 0 Fx FORWARD = 0. LOADING GENERALITIES b) Force breakdown Then for each tie-down point the force breakdown is : FX = F.5 F + 0.75 F = 1.5 F FY FORWARD = .5 F + 0.75 F FY UP = 0.86 F + 0.5 F FY AFT = .5 F = 5.43 F = 1.86 F + 0.5 F FY AFT = 0.5 F .43 F FZ UP = 0 86 F FZ FORWARD = 0 50 F TDLA : 2 straps : 1 UP and 1 AFT Fx UP = 0 Fx AFT = .cos(β) FY = F.43 F + 0.0.5 F .75 F FY UP = .5 F / nAFT Ultimate Load RIGHT = FY RIGHT / nRIGHT = 1.75 F FY UP = .0.5 F + 0.44 F d) Ultimate load Maximum Load Ultimate Load = Load Factor So the ultimate loads in each direction are: Ultimate Load FORWARD = FX FORWARD / nFORWARD = 1.86 F Fz = 0.75 F FY UP = 0.LOADING OPERATIONS A.75 F + 0.cos(α).5 F / nFORWARD Ultimate Load AFT = FX AFT / nAFT = 1.1. c) Maximum load So the maximum loads in each direction are: FX FORWARD = 0.5 F FX AFT = .0.43 F = .0.1.75 F . A. Then tables like the following one can be issued and published in the loading manuals of operators. adding each time a strap in the direction which limiting the ULTIMATE LOAD. Restraint AFT Left UP TDLA FORWARD Left UP TDLF AFT Right UP TDRA FORWARD Right UP TDRF Angle α β (°) (°) 30 150 60 90 30 60 30 60 30 60 30 90 210 90 330 90 FWD + 75% F 75% F 75% F 75% F Force Breakdown AFT LH RH + 75% F 43% F 50% F 75% F 93% F 43% F 50% F 93% F 75% F 43% F 50% F 75% F 93% F 43% F 50% F 93% F UP + 50% F 86% F 136% F 50% F 86% F 136% F 50% F 86% F 136% F 50% F 86% F 136% F Total Maximum Load Allowed Load Factor Ultimate Load ULTIMATE LOAD 150% F 150% F 186% F 186% F 544% F nFWD 150% F / nFWD nAFT nLEFT nRIGHT nUP 150% F 186% F 186% F 544% F / nAFT / nLEFT / nRIGHT / nUP Minimum of the Ultimate loads This method can be applied for as many as needed tie down points. LOADING GENERALITIES e) Summary This whole method can be summarized in the following table: Tie down Point Pos. Load to be restrained Number of single stud fittings kg less than 800 801 to 1420 1421 to 1600 1601 to 2400 2401 to 3200 3201 to 4010 > 4010 4 6 6 8 10 12 14 Number of straps hooked on 2 single stud fittings FWD AFT UP 1 1 2 2 1 3 2 2 3 3 2 4 4 3 5 5 4 6 6 5 7 Getting to Grips with Aircraft Weight and Balance 237 LOADING OPERATIONS . Angle Tie down Point Pos.LOADING OPERATIONS A. indeed by increasing this angle. Restraint AFT Left UP TDLA FORWARD Left UP TDLF AFT Right UP TDRA FORWARD Right UP TDRF α (°) 45 45 45 45 45 60 45 45 β (°) 145 90 45 90 225 90 315 90 FWD + 50% F 50% F 50% F 50% F Force Breakdown AFT LH RH + 50% F 50% F 70% F 50% F 120% F 50% F 70% F 120% F 50% F 50% F 70% F 50% F 120% F 50% F 70% F 120% F UP + 70% F 70% F 140% F 70% F 70% F 140% F 70% F 70% F 140% F 70% F 70% F 140% F Total Maximum Load Allowed Load Factor Ultimate Load ULTIMATE LOAD 100% F nFWD 100% F / nFWD 100% F 240% F 240% F 560% F nAFT nLEFT nRIGHT nUP 100% F 240% F 240% F 560% F / nAFT / nLEFT / nRIGHT / nUP Minimum of the Ultimate loads 238 Getting to Grips with Aircraft Weight and Balance . LOADING GENERALITIES Note : the recommended 30° between the rope or the strap with the main direction of restraint enables a high restrained force in the needed direction. one decreases the weight that can be restrained by the item. Nevertheless some operators might choose even when applying the recommended 30° to perform the computation with an angle of 45° in order to take into account a margin in case one of the ropes in not correctly tied down. B. SPECIAL LOADING SPECIAL LOADING INTRODUCTION Getting to Grips with Aircraft Weight and Balance 239 LOADING OPERATIONS . . vegetables and flowers) and the ground equipment used to load and unload the cargo compartments.1. LIVE ANIMALS AND PERISHABLE GOODS 1. in addition to the temperature. Getting to Grips with Aircraft Weight and Balance 241 LOADING OPERATIONS . − The presence of a high rate of carbon dioxide endangers the health of live animals and reduces the quality of fruits and vegetables. Several factors must be considered when livestock and perishable goods are transported: − Each animal specie or perishable good must be transported under specific condition of temperature. Therefore. a descent from high altitude into comparatively warmer air. but also sublimation of dry ice (used as a cooling medium for perishable goods) are the main causes for presence of CO2. or by moisture produced by live animals and perishable cargo.1. With some products. Generalities 1. fruits.1.B. several other factors must be considered: on the one hand. too much condensation may cause false smoke warnings. Condensation can be caused by a moist external ambient air. Main difficulties in animals and perishable goods transportation Live animals and perishable goods are particularly restricting shipments to transport. Moreover. SPECIAL LOADING B. Not only live animals. vegetables. and may cause death of live animals. SPECIAL LOADING 1. animals and perishable goods need a relatively fresh air. the ripening process is accelerated by the presence of ethylene. but they can be grouped into three main categories: ) Frozen goods: transported between –30°C and -12°C ) Other perishable goods: transported between -2°C and 20°C ) Live animals: transported between 0°C and 32°C − Condensation can deteriorate the quality of certain perishable goods. but on the other hand they give off substances which can be harmful. − Ethylene is a gas given off by horticultural products (fruits. LOADING OPERATIONS B.1.Notification to Captain” gives indications to the pilot about the required action on hold heating and ventilation controls (Refer to the “Operational Loading Documents” part of this manual). different rules should be applied: ⇒ A ventilated cargo compartment is recommended. It allows a removal of moist air. For the cargo to arrive in the best condition.2. external temperatures can be very high or very low depending on the phase of the transport considered. sea water. and ethylene. There are several reasons for this: cleaning compartments avoids the accumulation of dust. ⇒ In addition to the ventilation system. and it limits corrosion of the aircraft due to animals excreta. 1. it must be loaded as near as possible to the aircraft departure time and collected as soon as possible at the destination airport. When any live animal is on board.1.3. Responsibilities Transportation of live animals and/or perishable goods is under the sole responsibility of the operator who has to ensure a suitable environment for the load transported. ⇒ Containers must be cleaned thoroughly before and. should be used to transport live animals and perishable goods. the form “Special Load . Indeed. ⇒ When transporting live animals and perishable goods. after the flight. whereas the temperature in the compartment must remain stable. CO2. which may avoid false smoke warnings. or at least the most favorable route. a heating system ensures suitable conditions for their transport. 242 Getting to Grips with Aircraft Weight and Balance . ⇒ The most direct route. AIRBUS Industrie provides a range of optional ventilation and heating systems for installation in the FWD and AFT compartments of all the aircraft. fish slime or blood. SPECIAL LOADING 1. Ventilation and heating are provided as basic in the bulk compartments of all the aircraft except the A320 family where it is optional. the basic rule is “Last in – First out”. above all. ventilation limits the accumulation of dust. It is recommended to clean the compartments that have transported animals more frequently than given in the Aircraft Maintenance Manual. hair and feathers in the air extraction system ducts and on the lens of smoke detectors. Recommendations To transport perishable goods and live animals in good conditions. Moreover. too much carbon dioxide is dangerous to the animals’ health. It specifies the type of container to be used and the handling procedures to be followed for individual animal species. Within the EU. 1.2. moisture. and transiting through any EU member State. Unventilated cargo compartments Most of the countries have accepted the IATA Live Animals Regulations (LAR) as the directive for animal transportation by air. lighting…. SPECIAL LOADING 1.2. safety of handling staff and prevention of damage caused to aircraft. Reference documents a) SAE AIR 1600 A common reference document for live animals transportation is the norm called SAE AIR 1600 edited by the Society of Automotive Engineers (USA).2. b) IATA Live Animals Regulations Another reference book for the transport of live animals is the “IATA Live Animals Regulations” (LAR). but without ventilation supply to the cargo compartment. The purpose of this AIR (Aeronautical Information Report) is to provide information on the environmental conditions. It provides Air Conditioning engineers guidelines for the design of cargo air conditioning systems. limit rates have been imposed to the airlines when live animals are transported: − Relative humidity < 80% − Concentration of carbon dioxide < 3% (this limit is going to decrease over the next years) That’s why ventilation is therefore recommended when transporting live animals. Environmental limitations Animals give off heat. Article 29 is special provisions for transport by air.2. noise. that are required for the transportation of various live animals in the cargo compartments of civil commercial aircraft. Moreover. humidity. Special attention is given to animal comfort. Combination of high temperature and high moisture is not recommended because it reduces the animals’ ability to withstand the stress. It does not specifically ban the transport of live animals in unventilated compartments. It applies to all airlines of all nationalities. live animals transportation is also regulated by the Council of Europe document “European Convention for the Protection of Animals during International Transport (ETS65)”. temperature could not always be maintained in the appropriate range.1. This document states general rules for transportation by air of live animals. Paragraph 1 of Article 29 states “no animal shall be transported in conditions where air quality. Therefore.2. such as temperature. Live animals transportation 1. temperature and pressure cannot be maintained in an appropriate range during the entire journey”. carbon dioxide. out of. carbon dioxide and other gases.B. operating into.3. 1. Getting to Grips with Aircraft Weight and Balance 243 LOADING OPERATIONS . ETS65 covers the transport of live animals in general. 5. Loading rules General rules must be respected: ⇒ They must be loaded close to the cargo door ⇒ They must be protected against low temperatures: − Not directly loaded on the floor of the aircraft − Not directly loaded in front of or below the air inlets ⇒ A special care must be taken concerning the neighbourhood of the animal: − Enemy animals such as cats and dogs not in sight of one another − Males and females not close to each other − Sensitive animals not close to foodstuffs − Sensitive animals not close to human remains − Sick animals and “laboratory animals” separated from healthy animals ⇒ Animals must not be in close proximity of dangerous goods such as dry ice.2.4. except for tropical fish On the four sides of the container. cryogenic liquids. SPECIAL LOADING 1. Specific containers Live animals must be transported in suitable clean containers. radioactive materials. 1. Note: A table presenting loading incompatibilities of live animals with other cargo loads is proposed in the “Loading Operations” part of this manual. everything can be found about container’s specificity for each animal specie. but not straw because of its combustibility) − Tied down during the flight − Not closed containers. 244 Getting to Grips with Aircraft Weight and Balance .LOADING OPERATIONS B. the labels “Live Animals” and “This Way Up” must be placed. Some rules are common to all of them. Containers must be: − Strong enough to be stacked − Escape-proof for the handling staff to be in safety − Leak-proof (the use of an absorbent material is recommended. and poisonous and infectious substances.2. In the IATA LAR. It is dependent on the free air volume in the cargo compartment and the animal CO2 production. This manual enables to determine whether the planned load can be carried safely under given climatic and flight conditions. The confinement time is the time spent in a compartment without ventilation (from door closing to door opening). as well as the Maximum confinement time. destination airport and during the flight. destination airport and during the flight. The method proposed permits to calculate: • for a ventilated compartment: The Total Animal Heat Load and the Total moisture rate at the departure airport. while carrying live animals. • for an unventilated compartment: The Compartment temperature (without heat Load) at the departure airport.6. This method is based on a series of graphs and a Basic Data Form published in the Airbus Live Stock Transportation Manual (LTM). the method enables to evaluate if the temperature and humidity rate can be maintained in an appropriate range during the entire journey.2. The maximum confinement time is the maximum time to reach the maximum volumetric concentration of carbon dioxide (CO2). SPECIAL LOADING 1. Live Stock Transportation Manual (LTM) Airbus has developed a simplified calculation method allowing the calculation of heat load and moisture rate in a cargo hold.B. Depending on the cargo option (heating or not). Getting to Grips with Aircraft Weight and Balance 245 LOADING OPERATIONS . it is necessary to store fruits and vegetables under climatic conditions which are as close as possible to the ideal temperature and relative humidity. the temperature must remain between the following limits during the whole flight: . Package Some perishable goods.2. like meat and sea food. It is used as a cooling medium and must be used for frozen goods.3. vaccines and medical supply.3. wet materials not packed in watertight containers (eg fish packed in wet ice). or which by their nature may produce liquids (except dangerous goods). 246 Getting to Grips with Aircraft Weight and Balance . hatching eggs. humidity or other environmental conditions”. 1. fresh fruits and vegetables. live animals… (1) • Refrigerating material: Dry ice: the most effective refrigerant but classified as a “dangerous good” because it produces CO2. Since dehydration is caused by both high temperatures and low humidity.3. It must be frozen before use and has a gel-like consistency. Perishable goods 1. 1. require the use of watertight refrigerated and temperature controlled containers.1.3. As an example: liquids in watertight containers. flowers. SPECIAL LOADING 1. IATA Perishable Cargo Handling Manual The reference guide for packaging and handling of perishable goods by air is the IATA Perishable Cargo Handling Manual. The temperature should be maintained constant during the journey. This manual is published as an industry service under the authority of the IATA Cargo Service Conference. As an example. and must be treated as WET cargo(1). this concerns different types of products such as meat. and the relative humidity required is often very high (up to 90%).4. which can be dangerous for live animals and can damage some perishable goods.3.frozen meat or frozen fish: below – 12ºC Note: WET cargo concerns shipments containing liquids. Wet ice: ice made of frozen water. Indeed.LOADING OPERATIONS B. living human organs and blood. Gel ice: chemically based compound available in 2 forms (powder in plastic envelopes or sheets in plastic sachets). Dehydration Loss of water is a major cause of deterioration of fruits and vegetables.3. Definition Perishable cargo can be defined as “goods that will deteriorate over a given period of time. sea food. 1. or if exposed to adverse temperatures.fresh meat or fresh fish: between 0ºC and 5ºC . Other rules are specific to each species of perishable goods. dry ice and cryogenic liquids. SPECIAL LOADING Tº dry ice < Tº gel ice < Tº wet ice The use of gel ice is recommended for several reasons: contrary to dry ice. Note: A table presenting loading incompatibilities of perishable goods with other cargo loads is proposed in the “Loading Operations” part of this manual. Loading rules Before loading perishable goods.5. 1. eggs. There must also be a separation with radioactive materials.B. Getting to Grips with Aircraft Weight and Balance 247 LOADING OPERATIONS .3. it is an economically attractive way to keep perishable goods cool. Goods for human consumption must not be in close proximity of non-cremated human remains or live animals. • • • Some are incompatible because of a difference in temperature and/or humidity. it is harmless to food products and more durable. There is no risk of leakage and gel ice can be re-used over and over again: therefore. it is necessary to know the incompatibilities between different product types. others because of vapours or odours released. etc. Several other rules must be respected for the loading of perishable goods to avoid crushing: − Not in direct contact with the compartment floor or wall − A maximum stacking height − Not heavy package on top of fragile goods (fruits and vegetables. They can be found in the IATA Perishable Cargo Handling Manual. The labels “Perishable” and “This Way Up” must figure on the 4 sides of the package.) − Interlocking layers are recommended when a lot of ventilation is not needed. SPECIAL LOADING • Summary: Transportation of animals and perishable goods requires specific conditions that can vary depending on the product transported. heating is recommended for both of them. 248 Getting to Grips with Aircraft Weight and Balance . Airbus aircraft can be equipped with these two systems. a special care must be taken about incompatibilities between animals and/or perishable products. Ventilation is necessary to transport live animals. and is recommended to transport perishable goods. either as optional or as basic.LOADING OPERATIONS B. But even with ventilation and/or heating systems. SPECIAL LOADING 2. some cargo can hide hazards that may not be apparent. DANGEROUS GOODS 2.3.1. Here are some examples of hidden dangerous goods: − Articles found in passengers’ baggage that may contain flammable gas or liquid. − Frozen perishable goods or vaccines that may be packed with Dry Ice (solid carbon dioxide) − Parts of automobiles that may contain wet batteries or gasoline − etc. In addition to these two reference manuals. They contain all the requirements of the ICAO Technical Instructions. In this section. safety or property when transported by air” (per IATA Dangerous Goods Regulations). you will also find the list of state variations concerning dangerous goods. FAA or JAA may also apply as applicable and furthermore the local authorities of the country of departure and country of arrival may have strict regulations which have to be taken into account. The IATA Dangerous Goods Regulations are more applicable for practical reference by the industry. adopted by the Members of the International Civil Aviation Organization (ICAO) − The IATA Dangerous Goods Regulations published annually by IATA. 2.g. There are three types of dangerous goods: − goods too dangerous to be transported by air − goods transported with cargo aircraft only (called CAO shipments) − goods transported both with cargo and passenger aircraft To know to which category belongs a given good.B. matches.2. Some cargo may be hidden dangerous cargo: indeed. Getting to Grips with Aircraft Weight and Balance 249 LOADING OPERATIONS . 2. Responsibility Transportation of dangerous goods is under the sole responsibility of the operator (the shipper). declared under a general description. refer to the Limitations section of the IATA Dangerous Goods Regulations. aerosols. References Two references shall be used for transportation of dangerous goods: − the ICAO Technical Instructions For the Safe Transport of Dangerous Goods by Air. national regulations from e. but IATA has included additional requirements that are more restrictive. “Annex 18 to the Chicago convention and the associated Technical Instructions for the Safe Transport of Dangerous Goods by Air are recognized as the sole authentic legal source material in the air transport of dangerous goods”. but as indicated in the preface of the IATA Dangerous Goods Regulations. etc. Definitions Dangerous goods are “articles or substances which are capable of posing a significant risk to health. 1 .5 . The letters “UN” precede this number (when the UN number is not assigned yet. Each substance has its own UN number. Each hazard class is divided into several hazards divisions and specific labels are applied to each one of these classes and/or divisions: 2. a minor blast hazard and/or a minor projection hazard but not a mass explosion hazard − Division 1.Very insensitive substances having a mass explosion hazard − Division 1. Explosives Division 1.Articles and substances having a projection hazard but not a mass explosion hazard − Division 1.Extremely insensitive articles which do not have a mass explosion hazard Applicable labels are: − − 250 Getting to Grips with Aircraft Weight and Balance . a temporary “ID” number in the 8000 series is assigned).2 .6 . Identification “An operator shall take all reasonable measures to ensure that articles and substances are classified as dangerous goods as specified in the Technical Instructions.” (JAR–OPS 1. dangerous goods are classified into 9 hazard classes.3 .4 . is given to each dangerous article or substance.1.5. Symbol: 2. A number. SPECIAL LOADING 2.Articles and substances having a fire hazard. in the United Nations classification system.Articles and substances having a mass explosion hazard Division 1.LOADING OPERATIONS B. Classification Moreover.4.5.1170). This number is used for all ways of transport (not only air-transport) to identify the substance.Articles and substances presenting no significant hazard − Division 1. emit flammable gases − − − Division 4.3 .Flammable gas − Division 2.1 . emit flammable gas Applicable labels are: Getting to Grips with Aircraft Weight and Balance 251 LOADING OPERATIONS .3 . SPECIAL LOADING 2. Flammable solids.4.Non-flammable.Flammable solid Division 4.B.2. Substances liable to spontaneous combustion.Substances liable to spontaneous combustion Division 4. Flammable liquids Applicable label is: 2. non toxic gas − Division 2.Toxic gas Applicable labels are: 2. Gases − Division 2.5.5. Substances which.3.1 .Substances which.5. in contact with water.2 . in contact with water.2 . 5.Toxic substances Division 6.7.LOADING OPERATIONS B. Oxidizing substances and Organic Peroxide − − Division 5.1 .2 .5.1 .6.Oxidizer Division 5. Radioactive material Applicable labels are: 252 Getting to Grips with Aircraft Weight and Balance . Toxic and infectious substances − − Division 6.Organic peroxides Applicable labels are: 2.Infectious substances Applicable labels are: 2. SPECIAL LOADING 2.5.5.2 . 5.8.5. SPECIAL LOADING 2. Miscellaneous dangerous goods Applicable label is: Getting to Grips with Aircraft Weight and Balance 253 LOADING OPERATIONS .9. Corrosives Applicable label is: 2.B. − − 254 Getting to Grips with Aircraft Weight and Balance .1. the shipper can find packing instructions that detail the type of specifications required to transport each product depending on its class. I . SPECIAL LOADING 2.1 A + C → 5.2 B 5. The element that gives an indication on the degree of hazard substances present is the packing group: − − − Packing group I ➙ great danger Packing group II ➙ medium danger Packing group III ➙ minor danger Criteria for packing groups have only been developed for some classes and divisions. before packing any dangerous good.Subsidiary risk: 5. When a given substance presents more than one hazard. the shipper must: − Identify correctly and fully all dangerous articles and substances before transportation − Classify each item by determining its class or division and its subsidiary hazard − When it is possible. defective or leaking dangerous goods − Packaging can be reused or reconditioned under specific conditions − Several dangerous goods may be transported in the same outer packaging under specific conditions One last condition about package of dangerous goods is that it must be of such a size that there is enough space to affix all required markings and labels. Here are general packing requirements (for more details. Example: CLASS OR DIVISION PACKING GROUP − − A 4.2 II III I Therefore.1 A + B → 4.LOADING OPERATIONS B.Subsidiary risk: 4. the least stringent hazard is called the subsidiary hazard.2. In the 5th section of the IATA Dangerous Goods Regulation. Most dangerous goods must be packed with both an inner and an outer packaging. the most stringent class and packing group must be applied to this substance. Packing The order in which classes and divisions are numbered does not imply a relative degree of danger. II . assign each item to one of the three packing groups The shipper is responsible for all aspects of the packing of dangerous goods in compliance with the IATA Dangerous Goods Regulations.1 C 5.6. A table provided in the 3rd section of the IATA Dangerous Goods Regulations helps in determining which one of the two hazards must be regarded as the primary hazard. refer to the 5th section of the IATA Dangerous Goods Regulations): Dangerous goods packaging must be of a good quality Packaging in direct contact with dangerous goods must be resistant to any chemical action of such goods − Salvage packaging must be used for damaged. SPECIAL LOADING 2.B.7. Marking and labeling All packages containing dangerous goods are to be marked and labeled in order to ensure immediate identification during all phases of transportation. − Each package is labeled thanks to the dangerous goods hazard labels we have seen above (minimum size: 100 x 100 mm). handling information shall be shown on the packages thanks to the following labels: − This Way Up Cargo Aircraft Only Getting to Grips with Aircraft Weight and Balance 255 LOADING OPERATIONS . − If necessary. First of all. the packaging must bear the UN number and the shipping name of the substance it contains. LOADING OPERATIONS B. 256 Getting to Grips with Aircraft Weight and Balance . Air Waybill The IATA Air Waybill Handbook gives all the instructions necessary to complete an Air Waybill. An Air Waybill is compulsory whenever dangerous goods are transported.8. Moreover.1.8. for each shipment containing dangerous goods. Documents The presence of special loads such as dangerous goods should be noted on the load sheet and the load message. The “Handling information” box of the Air Waybill gives information about: − − − the presence of dangerous goods on board the presence or not of a “Shipper’s Declaration for Dangerous Goods” the way the dangerous goods must be transported (Cargo Aircraft Only or Passenger aircraft) Example: Dangerous goods for which a Shipper’s Declaration is required and transported on a passenger aircraft. the shipper must fill in special forms: 2. SPECIAL LOADING 2. 8. Shipper’s Declaration for Dangerous Goods Thanks to the “Shipper’s Declaration for Dangerous Goods”.Information about dangerous goods transported 8 . 3 1 2 4 5 6 7 Red Hatching 8 9 Information about the shipper Information about the consignee Number of the Air Waybill attached Page number Enter the full names of the airports (not ICAO codes) Radioactive material must not be on the same declaration as other dangerous goods. SPECIAL LOADING 2. 7 . A Shipper’s Declaration for Dangerous Goods is provided on the following page. except dry ice (used as a refrigerant for perishable goods — cf.The shipper commits himself to respect regulations concerning transportation of the shipment 123456- Getting to Grips with Aircraft Weight and Balance 257 LOADING OPERATIONS . the shipper certifies that dangerous goods have been properly prepared for shipment. next part).Particular information about the shipment 9 .2.B. − Handling instructions on the package must be respected (This Way Up. − When an Auxiliary Center Tank (ACT) is installed in a cargo compartment. Special Load – Notification to Captain Thanks to this form. etc. it is necessary to inspect the outer packaging of dangerous goods to determine there is no hole or leakage. − Some goods may react dangerously with others. SPECIAL LOADING 2. the flight crew is aware of the presence of dangerous goods on board.3. corrosive or explosive material shall be transported in this compartment − After unloading. It is also used to indicate the presence of live animals or perishable cargo which transportation is developed below. 258 Getting to Grips with Aircraft Weight and Balance .8. they must always be handled with care. other loads or being loaded in different compartments shall physically separate incompatible goods from others.LOADING OPERATIONS B. The table of incompatibilities is provided in the AHM 645. Moreover. Handling and loading Competent persons that have received an appropriate training concerning dangerous goods shall only execute handling and loading. The following form is used: SUCH AS LIVE ANIMALS OR PERISHABLE GOODS 2. A few rules are to be respected: − First of all. the outer packaging must be inspected for evidence of damage or leakage. To avoid any interaction. − Dangerous goods must never be carried on the same deck as passengers or crewmembers.).9. before loading. no combustible. B. CORROSIVES Corrosives shall not be loaded next to dangerous goods classified as explosives. Special shipments 2. SPECIAL LOADING 2. CARBON DIOXIDE.0 The transport index of a single package is limited to 10 and the transport index of the whole shipment is limited to 50.1. flammable solids. Its value is shown on the labels affixed on the package. no corrosive materials should be transported in close proximity of them. − Category I .10. Even when they are loaded in different ULDs. minimum horizontal and vertical distances must separate these radioactive packages from each other and from passengers.10. Moreover. SOLID (DRY ICE) Dry ice is used as a refrigerant for perishable goods transportation. hatching eggs and undeveloped photographic films. Packaging containing radioactive materials of categories II and III must be separated from live animals. TOXIC AND INFECTIOUS SUBSTANCES Such substances shall not be loaded in the same section or ULD as live animals or foodstuffs.2. − Dry ice shall not be loaded in close proximity of live animals or hatching eggs.10.no TI − Category II – 0 < TI ≤ 1. Moreover. 2.1 ≤ TI ≤ 10. There is no specific restriction concerning radioactive materials from category I.10. it must be ventilated before the staff enters in it.10. RADIOACTIVE MATERIALS There are three different categories of radioactive materials depending on the Transport Index (TI) of the package. 2. 2. oxidizing substances or organic peroxides. Loading regulations shall be applied such as: − When there is dry ice in a compartment.3. whenever ACTs are installed in the aircraft. The TI number expresses the maximum radiation dose rate at 1 meter away from the external surface of a package containing dangerous goods. during the flight.4. the ULDs must be separated Getting to Grips with Aircraft Weight and Balance 259 LOADING OPERATIONS .0 − Category III – 1. . C. This manual must be used as a reference to help building specific airline policies in accordance with national regulations. These main documents are: − Loading Instruction / Report form (LIR) − Container/Pallet distribution message (CPM) − Loadsheet − Loadmessage (LDM) − Balance chart / balance table In these different documents. Getting to Grips with Aircraft Weight and Balance 261 LOADING OPERATIONS . Operational Loading Documents OPERATIONAL LOADING DOCUMENTS INTRODUCTION IATA AHM part 5 describes in detail all the different types of traffic documents and messages to be used for handling operations. Our goal in this chapter is to provide the reader with a general description of the main documents used in operations for a better understanding of the load control function. codes are used and it is recommended that operators comply with the proposed codification of IATA AHM 510 recalled hereafter. . Load Information Codes The following codes enable to define the type and priority of deadload transported in the cargo holds. LOAD AND VOLUME INFORMATION CODES 1.1. OPERATIONAL LOADING DOCUMENTS 1. Code 0 1 2 3 Description No volume available Quarter volume available Half volume available Three quarters volume available Getting to Grips with Aircraft Weight and Balance 263 LOADING OPERATIONS . Code B C D E F H M N Q S T U W X Z Description Baggage Cargo Crew baggage Equipment in compartment First class baggage and/or priority handled baggage ULD and/or its load to be transshipped to a connecting flight (destination or flight number indicated in Supplementary Information part of the CPM) Mail No ULD at position Courier baggage Sort on arrival Load for transfer to connecting flights Unserviceable ULD Cargo in security controlled ULD Empty ULD Load deliberately mixed by destination when these destinations are known to be beyond a planned 1.C. To be used on the LIR and the CPM. ULD Load volume codes The following codes provide a transit station with information about the available volume in a cargo section or an ULD. To be used on the LIR and the CPM.2. Operational Loading Documents C. Loadsheet. Dry ice Live Human Organs/Blood Magnetized material Miscellaneous Operational Staff No item loaded Obnoxious deadload Passenger Available for Disembarkation Hunting trophies.HUM/42P/210 .LOADING OPERATIONS C. Code AOG AVI BAL BED BEH BIG COM CSU DHC DIP EAT EIC FIL FKT HEA HEG HUM ICE LHO MAG MOS NIL OBX PAD PEA PEF PEM PEP PER PES R.WET/41R . mail Valuable cargo Wet materials not packed in watertight Priority small package LDM format .PEF/4 Loaded in 11P Loaded in CPT3 Loaded in 41P Loaded in CPT1 Loaded in 31L Sum of Transport Indexes = 6.HEA/2/216 . and LDM.CSU/22R/500 . skin. 12 in Y class Eg : fish packed in wet ice 264 Getting to Grips with Aircraft Weight and Balance .3. RRY SOC VAL WET XPS Description Spare part for Aircraft On Ground Live Animals Ballast hold loaded Stretcher installed Stretcher in cargo hold Item loaded on two or more pallets Company mail Catering equipment not used for flight Crew occupying pax seats (not on duty) Diplomatic Mail Foodstuff for human consumption Miscellaneous items not included in DOW Undeveloped Film/Unexposed film Flight Kit Heavy cargo (above 150 kg per piece) Hatching eggs Human remains in Coffins Carbon dioxide.BAL/5/100 . Codes used for loads requiring special attention The following codes (non exhaustive list) indicate in the LIR. the content of the dead load requiring special attention.FKT/53/450 .BED/6/2Y .AVI/4 .EIC/4/50 .EAT/31R .RNG/31L .PES/1 .MOS/0/2/0 . … Flowers Meat Fruit and vegetables Perishable goods Seafood/Fish for human consumption Dangerous goods Radioactive Category II and III Seats occupied by baggage.4 6 seats in F/B class.SOC/6/12 Not to be used .HEG/32L .FIL/3 .PER/41P .DHC/0/2/5 .ICE/11R .BIG/11P12P/26 50 . Operational Loading Documents 1.LHO/2 Not to be used .RRY/41P/6PT4 .COM/42L/216 .PEM/11P . cargo. 5 in Y class 2 bags loaded in CPT1 Loaded in 31R 50 kg loaded in CPT4 CPT3 450 kg loaded in section 53 216 kg loaded in CPT2 ULD position 32L 210 kg loaded in 42P Loaded in 11R Loaded in CPT2 Not mentioned in LDM 2 seats in B class Loaded in 12P 1 seat in B class.XPS/41P Remark ULD position 12L Loaded in CPT4 100 kg ballast in CPT5 6 seats blocked by 2 pax in Y Position 33.OBX/12P ..PEP/3 .AOG/12L . CPM.PAD/0/1/5 .DIP/1/2 .BEH/33/50 . 50 kg 2650 kg loaded on 11P + 12P 216 kg loaded in 42L 500 kg loaded in 22R 2 seats in B class.. 5 in Y class Loaded in CPT2 .PEA/2 . taking into account several constraints such as Zero Fuel CG position. is prepared and filled in by the Load Planner once he knows how much load can be transported. cargo options (ventilation. weight limitations. live animals. Getting to Grips with Aircraft Weight and Balance 265 LOADING OPERATIONS . it allows the Loading Supervisor to know everything about the shipment (nature. specific loading constraints (dangerous goods. etc…) and to report the loading distribution is effectively performed. loading/offloading rules. LOADING INSTRUCTION / REPORT (LIR) 2. Introduction This form is a means of communication between the Load Planner and the Loading Supervisor. On the one hand.C. distribution. The Loading Instruction / Report form (LIR). and on the other hand.1. To determine this data. Operational Loading Documents 2. incompatibilities. CG limitations. heating) Once the load is known. the Load planner determines its distribution into the cargo holds. perishable goods…). it allows the Load Planner to give loading and off-loading instructions to the Loading Supervisor. the load planner needs information from : − Passenger booking : to calculate the forecasted passenger weight and associated − Baggage weight (number of containers required in case of CLS) − Dispatch : to know what is the available payload according to the fuel required for the flight − Incoming LDM/CPM : to know the cargo distribution and if there is transit cargo/mail in case of multi-sector flights − Cargo department : to know if cargo is available for the flight − Aircraft type : weight limitations. mail…) through a one letter code (as per AHM 510) − the estimated weight of the load − the nature of the shipment in case of special loading (as per AHM 510) − the available volume in the section (as per AHM 510) 266 Getting to Grips with Aircraft Weight and Balance . and from the incoming LDM for others.Heading: Station. such as dangerous goods. and of any change in the transit load position in case of multi-sector flights.Loading Instructions: Gives indications on where the load must be stowed. since the destination of each load is clearly indicated on the form. live animals. the following information is required. Local date. for each hold section. the destination must be clearly indicated by the 3-letter IATA airport codes.Special instructions: gives any information that might be considered as important or useful by the Load Planner. Any deviations from the original Loading Instructions must be noted or transmitted before the flight departure to the loadsheet agent. cargo. relocation of some cargo to balance the aircraft. The Load Planner has to fill in the header part. Flight number. Operational Loading Documents 2. D . name of the Load Planner who prepared it. but for all of them. E . F . Information shown in this section reflects the exact state of the shipment loaded in the aircraft before departure. Cargo that must be off-loaded at the transit station may be encircled. lashing of heavy items. but the loading agent knows what he must off-load. airway bill of dangerous goods… G . it is used to confirm that the aircraft has been loaded in accordance with the given instructions.Arrival (for multi-sector flights only): gives details about the incoming loads for intermediate stops. the arrival part from the incoming LDM/CPM (in case of multi-sector flights) as well as the Loading Instructions part. A . In this case.Signatures: Two names and two signatures are required: The Load planner who prepared the Loading Instructions The Loading Supervisor. as stated in IATA AHM 515. B . the following items: − the destination of the shipment (3-letter IATA code) − the ULD type and ID code (for ULDs aircraft) − the content of the section (Baggage. Information contained in this section is copied from the incoming CPM for aircraft equipped with ULDs. who performed the Loading. Destination(s). to confirm that the aircraft is loaded in accordance with the instructions or to advise of any deviations. To give its loading instructions. C .LOADING OPERATIONS C. Aircraft registration.2.Compartment number and Weight limitations: clearly indicates the weight limitations for each cargo hold. Manual LIR The layout of the LIR may vary with aircraft type or with airline. the load planner must use.Loading reports: completed by the Loading Supervisor. C. Operational Loading Documents Getting to Grips with Aircraft Weight and Balance 267 LOADING OPERATIONS . PER (Live Animals + Perishable goods) 12L JFK F (First class/priority baggage) 2 (Half volume available 41P JFK/PAG 1234AI/ C/2480/AVI.LOADING OPERATIONS C. Operational Loading Documents Example : Hold section Destination Pallet ID Content Weight Special load Hold section Destination Pallet ID Volume 41P JFK PAG 1234AI C (Cargo) 2480 kg AVI.PER 12L JFK/F2 268 Getting to Grips with Aircraft Weight and Balance . • Example of an EDP LIR: Cpt capacity Hold section Pallet ID Origin Destination Content Special load Report : : : : : : : : 13380 kg 12P PAG 2503AI CDG JFK Cargo (1850 kg) RFL (See summary : one piece. To avoid reporting the load distribution on a manual LIR. According to AHM 514. These reports must be signed by the persons responsible for loading and/or offloading. a computerized “Loading Instruction / Report” form can be directly printed. it is recommended to issue a Loading Instruction/report form for each departing flight.3. Airway Bill 055 235324) 3225 kg (Actual weight reported by the loading supervisor) Getting to Grips with Aircraft Weight and Balance 269 LOADING OPERATIONS . Operational Loading Documents 2. AHM 514 recommends a “Summary of special loads” to be issued. Note that due to limited space. Transport Index 2. In case of loads requiring special attention. integrated load control systems enable to prepare loading instructions and to visualize simultaneously the effect of the load on the center of gravity of the aircraft.C. EDP LIR Nowadays. only the occupied ULD positions or hold sections may be shown. Airway Bill 034 99222) 1850 kg (Actual weight reported by the loading supervisor) A CPT 1MAX 13380 : 12PPAG 2503AI : ONLOAD:JFK C / 1850 : SPECS:SEE SUMMARY : REPORT:1850 B CPT 2MAX 10206 : 21PPAG 5421AI : TRANSIT:JFK C / 3225 : SPECS:SEE SUMMARY : REPORT:3225 Cpt capacity Hold section Pallet ID Origin Destination Content Special load Report : : : : : : : : 10206 kg 21P PAG 5421AI (Transit in CDG) JFK Cargo (3225 kg) RRY (See summary : one piece. .LOADING OPERATIONS C. 3730 6 955 REPORT: CPT 2 TOTAL : ************************************************************************************************************************************** CPT 4 MAX 10206 : : 41L AKE1245AI : 41R AKE4567AI : : ONLOAD: JFK B / 810 : ONLOAD: JFK B / 810 : 800 800 : REPORT: : REPORT: : ………………………………………………………………………………………………………….……….. 1980 3 830 REPORT: CPT 1 TOTAL : ************************************************************************************************************************************** CPT 2 MAX 10206 : : 21P PAG5421AI : : TRANSIT: JFK C / 3225 : : SPECS: SEE SUMMARY : 3225 : REPORT: : …………………………………………………………………………………………………………. Operational Loading Documents • EDP LIR example LOADING INSTRUCTION/REPORT PREPARED BY EDNO Jones ALL WEIGHTS IN KILOS 01 FROM / TO FLIGHT A/C REG VERSION GATE TARMAC DATE TIME CDG JFK AI0533 OOTPA C18/Y264 B40 H10 30DEC00 1405 PLANNED JOINING LOAD JFK F 0 C 16 Y204 C 10785 M 0 B 4300 JOINING SPECS : SEE SUMMARY TRANSIT SPECS: SEE SUMMARY LOADING INSTRUCTIONS ************************************************************************************************************************************** CPT 1 MAX 13380 : : 12P PAG2503AI : : ONLOAD: JFK C / 1850 : : SPECS: SEE SUMMARY : 1850 : REPORT: : ………………………………………………………………………………………………………….: : 22P PAG4521AI : : TRANSIT JFK C / 3730 :……….…………. SIGNATURE JONES Italic characters represent the loading supervisor inputs 270 Getting to Grips with Aircraft Weight and Balance ...: : 13P PAG3251AI : : ONLOAD: JFK C / 1980 :……………..: : 42L AKE4561AI : 42R AKE8424AI : : ONLOAD: JFK B / 810 : ONLOAD: JFK B / 810 : 750 750 : REPORT: : REPORT: : …………………………………………………………………………………………………………..………... THE CONTAINERS / PALLETS AND BULKLOAD HAVE BEEN SECURED IN ACCORDANCE WITH COMPANY INSTRUCTIONS.………...………….……. 800 400 4300 : REPORT: : REPORT: CPT 2 TOTAL : ************************************************************************************************************************************** : SI A B THIS AIRCRAFT HAS BEEN LOADED IN ACCORDANCE WITH THESE INSTRUCTIONS AND THE DEVIATIONS SHOWN ON THIS REPORT.……….: : 43L AKE5624AI : 43R AKE4093AI : : ONLOAD: JFK B / 810 : ONLOAD: JFK F / 480 :………. this can allow both automatic transmission and reading of any CPM. their destination (for multi-sector flights). IATA AHM 587 gives information about the standard format of the Container/Pallet distribution message. Indeed. 3.Standard message identifier and flight record 3. The codes used for the CPM come from IATA AHM 510. It is not requested to send a loadmessage on a single leg flight or on the last leg of a multi-sector flight. as well as their weight and content.Supplementary information Getting to Grips with Aircraft Weight and Balance 271 LOADING OPERATIONS . most of the carriers systematically send CPMs as it enables the destination station to prepare the adequate equipment and manpower for handling containers and pallets. Nevertheless. All the ULD positions. CONTAINER/PALLET DISTRIBUTION MESSAGE (CPM) The Container/Pallet distribution message only concerns aircraft equipped with Unit Load Devices (ULDs). A need exists for an automatic readable format for the CPM.Distribution and load information 4.. including those not occupied by an ULD..Example TO JFK FLIGHT AI0533 A/C REG OOTPA VERSION C18/Y264 GATE B40 TARMAC H10 DATE 30DEC00 TIME 1405 FROM / CDG LOCN JOIN/ DEST CAT IMP PCS WEIGHT TI AWB TRAN ************************************************************************************************************** 12P JOIN JFK C RFL 1 034 99222 ……………………………………………………………………………………………………………….Teletype addresses and communication reference 2. The message is composed of four parts: 1. 21P TRAN JFK C RRY 1 Opt 2 055 234324 ************************************************************************************************************** SI …. This message shall provide the type and the distribution of the ULDs. Operational Loading Documents • “Summary of special loads” . must be shown on the message.C. as well as automatic distribution of ULDs by EDP systems.. baggage to be transferred onto this flight % 272 Getting to Grips with Aircraft Weight and Balance .LOADING OPERATIONS C.FIL -21P/JFK/3225/C. cargo load containing radioactive materials whose sum of Transport Indexes is equal to 1.5 -31P/N Position 31P empty (No ULD) -42L/JFK/750/B1 ULD position 42L. transfer baggage. ¼ volume available -42R/JFK/750/H/TB1 ULD position 42R. destination JFK.RRY/1PT5 -13P/JFK/1980/C.C18/Y264 Aircraft configurati on $ -11L/X-11R/X Empty ULD in position 11L – Empty ULD in position 11R -12P/JFK/1850/C. weighing 750 kg.PER -22P/JFK/3730/C -31P/N -32P/N -41L/JFK/800/B0-41R/JFK/800/B0 -42L/JFK/750/B1-42R/JFK/750/H/TB1 -43L/JFK/800/B1-43R/JFK/400/F3 SI -42R/UA256/PIT/TB % QU Priority (urgent) . connecting flight UA256 to PIT. destination JFK. ¼ volume available SI (Supplementary Information) –42R/UA256/PIT/TB ULD position 42R. containing a load to be transferred to a connecting flight (destination or flight number indicated in SI). weighing 1850 kg. containing baggage. destination JFK.CDGKLAI Originator # JFKKLAI Address 1 AI/301505 Facilit / y AI / JFKKKAI Address 2 D / at e 30 / Time CDGKKAI Address 3 15h05 & CPM (Message identifier) AI533/30 .OOTPA.C18/Y264 -11L/X-11R/X -12P/JFK/1850/C. Operational Loading Documents # & $ CPM example QU JFKKLAI JFKKKAI CDGKKAI .CDGKLAI AI/301505 CPM AI533/30. weighing 750 kg.OOTPA Flight Aircraft number/date registration .RRY/1PT5 ULD position 12P. It is often necessary to adjust it after completion to take into account “Last Minutes Changes” (LMC). before each departure. The loadsheet must reflect the actual state of the aircraft before takeoff. the weight that must be unloaded at the different stations is indicated. This form gives information about the weight of the aircraft as well as the distribution of the load in the different cargo holds. IATA AHM 516 gives recommendations about the kind of information that must appear on a loadsheet. which can be manual or computerized (EDP loadsheet). distributed as follows: − one copy for the aircraft − one copy for the departure station file − one or two copies for the carrier. Introduction The loadsheet is a document prepared and signed by the loadsheet agent at the departure airport.1. Nevertheless. Operational Loading Documents 4. that the weight of the shipment is consistent with the structural limitations of the aircraft. if required Airlines often use their own loadsheet format. LOADSHEET 4.C. Getting to Grips with Aircraft Weight and Balance 273 LOADING OPERATIONS . The loadsheet must be issued in not more than four-fold. The loadsheet allows to check. In case of multi-sector flights. Manual loadsheet • Manual Loadsheet example 1 3 7 2 4 8 5 6 9 A 10 1 2 5 6 3 4 B 1 2 3 2 1 3 C 4 9 5 6 7 8 D 10 1 2 1 3 4 2 3 4 5 3 6 4 5 6 7 E 1 5 2 G F 274 Getting to Grips with Aircraft Weight and Balance .2. Operational Loading Documents 4.LOADING OPERATIONS C. As an example: . ZZ: code of the company (airline code or XH for external handling companies) 3 . 2/9 : 2 cockpit crew + 9 cabin crew . L = Load control department) .Operators initial 6 . 2/2/7 : 2 cockpit crew + 2 cabin crew male + 7 cabin crew female B : Operating weight calculation 1 .C. eg KK (K = Operations department.Operating weight (B3) Getting to Grips with Aircraft Weight and Balance 275 LOADING OPERATIONS .Number of cockpit crew / cabin crew : eg 2/9 or 2/2/7 . Recharge facility : AF . Y218 : 218 economic seats 10 . eg KL (K= Operations department. K = Station manager) . C42 : 42 business seats . (MLW+Trip Fuel) Allowed traffic load = Allowed weight for takeoff (C5) . Flight number : SN551 . YY : destination department. Date : 25 .Version code of the aircraft used : eg C42Y218 . Identifier : 25 (date as an example) 8 .Operating weight = Dry operating weight + Takeoff fuel C : Allowed traffic load calculation 123456MZFW = Certified Maximum Zero Fuel Weight MTOW = Certified Maximum TakeOff Weight MLW = Certified Maximum Landing Weight Trip fuel from dispatch Allowed weight for takeoff = Lowest of (MZFW+Takeoff Fuel).Flight number/identifier : eg SN551/25 . XXX : destination airport (3 letters IATA code) . Operational Loading Documents A : Addresses and heading 1 . MTOW.Takeoff fuel from fuelling order 3 .Aircraft registration 9 .Priority code (QU = urgent. QD = Standard) 2 .Dry Operating Weight = Basic weight + Crew + Pantry 2 .Teletype address of originator (XXXYYZZ) 4 .Teletype address for loadmessage as required (XXXYYZZ) .Standard message indicator (LDM for loadmessage) 7 . Time : 10h05 AM 5 .Recharge facility/Date/Time : eg AF/251005 . LW = TOW (E3) . while structural limitations are still respected. Infants.Additional remark as per IATA AHM 510 recommendations (HEA.Total number of outgoing passengers and outgoing deadload (1) When not included in passenger weight E : Actual gross weight calculation 1 .Trip fuel (C4) 5 .Total weight of deadload (Tr: deadload in transit. RFL. HUM…) 9 .Weight distribution per cargo hold and per type (Tr. including PADs (Passengers Available for Disembarkation: no firm booking. Adults/Females. AVI.LOADING OPERATIONS C. C.Destination airports (several in case of multi-sector flights) 2 . Adults/Females.Number of passengers joining at this airport (Males. 1 .Total Traffic Load = Total outgoing deadload (D10) + Total cabin baggage weight(1) (D10) + Total outgoing passenger number (D10) x passenger weight(2) 2 .Underload before LMC(3) = Allowed traffic load (C6) – Total traffic load (E1) Irrelevant when cabin baggage weight is included in the passenger weight Passenger weight with or without baggage weight (company policy) (3) The underload before LMC represents the extra weight that can be added at the last minute. RRY. M) 6 . B: joining baggage. M: joining mail) 5 .TOW = ZFW (E2) + Takeoff fuel (B2) 4 . Total cabin baggage weight(1)) 3 .Total number of seats occupied by outgoing PADs per class 8 . Operational Loading Documents D : Load information per destination and totals This section provides information about the number of passengers as well as on the deadload (weight and distribution) for each destination of the flight. (2) (1) 276 Getting to Grips with Aircraft Weight and Balance . Children. low priority) 7 .Total number of seats occupied by outgoing passengers per class. B. Infants. Children. C: joining cargo.Number of outgoing passengers and outgoing deadload per destination 10 .Number of passengers in transit and continuing to the next destination airport (Males.ZFW = Total traffic Load (E1) + Dry operating weight (B1) 3 . Cabin baggage(1)) 4 . only changes in the weight or distribution of the traffic load (passengers. 4 . G : Supplementary information and notes 1 . When the tolerance is exceeded. This is the aim of Last Minute Changes (LMC). baggage.Approved by: Captain’s signature Getting to Grips with Aircraft Weight and Balance 277 LOADING OPERATIONS .Seating conditions: according to carrier requirement 5 . TOW (E3) and LW (E4).: Sum of all LMC weights (on or off-load) The total weight increase due to LMC (F6) must not exceed the underload before LMC (E5).SI: supplementary information transmitted with LDM (free format) 2 .Balance condition: balance conditions according to carriers requirement (MACZFW. cargo and mail) should be mentioned in the LMC box.…) as per AHM 050. weight of deadload) Cpt: Cabin section or cargo compartment in which the LMC is added +/-: Indication of on or off-load Weight : Weight increment or decrement for the specific LMC LMC Total +/.Notes: Information not transmitted with LDM 3 . This tolerance should be established per aircraft type (company policy).Prepared by: Loadsheet agent’s signature 7 . it is often necessary to adjust it after completion.Total passengers: Total number of passengers on board (including LMC) 6 . Nevertheless. Operational Loading Documents F : Last minutes changes (LMC) As the loadsheet must reflect the actual loaded state of the aircraft before departure. 123456- Dest : Destination of LMC Specification : Kind of LMC (number of passengers. No subsequent corrections are to be made to the previously calculated ZFW (E2). Generally. a new loadsheet must be issued.C. any deviation of the DOW conditions could be added as well. provided the weight increment remains below a pre-determined tolerance. MACTOW. . cargo. (Refer to “Balance calculation methods”) UNDERLOAD BEFORE LMC CAPTAIN INFORMATION/NOTES …..LOADING OPERATIONS C. According to IATA AHM 517.3. That’s why it is advisable to adjust passenger and load figures before the final version is printed or sent to the aircraft. EDP loadsheets can be issued very quickly at the last minute. This enables to avoid Last Minute Changes on the loadsheet. an EDP loadsheet must look like the following example: • EDP loadsheet example CHECKED A/C REG OOTPA APPROVED VERSION C18Y264 CREW 2/9 DATE 30DEC00 EDNO 02 TIME 1405 LOADSHEET ALL WEIGHTS IN KILOS FROM/TO CDG JFK FLIGHT AI0533 LOAD IN COMPARTMENTS PASSENGER/CABIN BAG WEIGHT 10785 DISTRIBUTION 1/3830 2/6955 4/4300 TTL 220 SOC BLKD A CAB 16905 190/ 27/ 3 PAX CY 16/204 B ************************************************************************************************************** TOTAL TRAFFIC LOAD DRY OPERATING WEIGHT ZERO FUEL WEIGHT TAKE OFF FUEL TAKE OFF WEIGHT ACTUAL TRIP FUEL LANDING WEIGHT ACTUAL 27690 123250 150940 65500 216440 58600 157840 MAX MAX MAX 168000 230000 180000 BALANCE AND SEATING CONDITIONS BALANCE AND SEATING CONDITIONS According to carrier requirement . END LOADSHEET EDNO 02 AI0533 30DEC00 140535 Deadload information Cargo 1 : 3830 kg Cargo 2 : 6955 kg Cargo 4 : 4300 kg Total : 10785 kg Passenger information Adult : 190 / Children : 27 / Infant : 3 Business class (C) : 16 pax Economic class (Y) : 204 pax Total number : 220 pax Total weight : 16905 kg 278 Getting to Grips with Aircraft Weight and Balance . generally besides the aircraft.. mail and passenger boarding information are interconnected. EDP Loadsheet With computerized Load control systems. Operational Loading Documents 4. LOAD MESSAGE BEFORE LMC 13560 LAST MINUTE CHANGES DEST SPEC CL/CPT WEIGHT LMC TOTAL ************************************************************************************************************** …. A copy of the final loadsheet must be printed on ground. Operational Loading Documents 4. According to IATA AHM 518. the loadsheet must be headed “Prelim” or “Final” to prevent from any confusion.C. It is recommended to get the acknowledgement from the cockpit crew. The transmission by the loadsheet agent must be done at a time that ensures that no further adjustments will be necessary. signed by the loadsheet agent and stored in the flight’s file. ACARS loadsheet The ACARS loadsheet format is designed to provide only essential data. any correction should be done verbally. this system must ensure that only one final loadsheet will be transmitted. After transmission of the final loadsheet. • ACARS loadsheet example LOADSHEET FINAL 1505 AI05333/30 30DEC00 CDG JFK OOTPA 2/9 ZFW 150940 MAX 168000 TOF 65500 TOW 216440 MAX 230000 TIF 58600 LAW 157840 MAX 180000 UNDLD 13560 PAX /0/16/204 TTL220 BALANCE AND SEATING CONDITIONS According to carrier requirement (Refer to “Balance calculation methods”) SI .4. ENDAI0533 ACARS loadsheet status : Final Sent at : 15h05 Flight Number/Day : AI0533/30 Date : 30 DEC 2000 Departure : CDG Arrival : JFK A/C Registration : OOTPA Crew : 2 cockpit / 9 cabin Zero Fuel Weight : 150940 kg Max Zero Fuel Weight : 168000 kg Take Off Fuel : 65500 kg Take Off Weight : 216440 kg Max Take Off Weight : 230000 kg Trip Fuel : 58600 kg Landing weight : 157840 kg Max Landing Weight : 180000 kg Underload : 13560 kg Passengers per class : 16 B / 204 Y Total number of pax : 220 SI : Supplementary Information Getting to Grips with Aircraft Weight and Balance 279 LOADING OPERATIONS .. When the ACARS loadsheet is generated by an EDP system. Balance chart 280 Getting to Grips with Aircraft Weight and Balance . Indeed.2. directly deduced from the center of gravity position of the aircraft. The main reason is the flight safety. BALANCE CALCULATION METHODS 5. Another reason is an operational reason: the crew must be able to correctly trim the aircraft for takeoff by selecting the appropriate THS (Trimmable Horizontal Stabilizer) angle. Introduction It is necessary to determine.1.LOADING OPERATIONS C. Different methods are available to determine the influence of each item on the aircraft balance: 1 Manual method : Balance chart / Balance table 2 EDP method 5. the center of gravity position of the aircraft. Manual balance calculation method 5. Operational Loading Documents 5.1. An aircraft is a combination of several items that have a particular weight and a particular location. before takeoff.2. it is necessary to ensure that the aircraft CG will remain within pre-determined limits during the whole flight. C. Operational Loading Documents • Balance chart example A H J I B C D F E G K Getting to Grips with Aircraft Weight and Balance 281 LOADING OPERATIONS . Thus. The position and numbering of holds and compartments C – Index units as the first scale D – For each compartment or cabin section : . Other optional information may appear on the balance chart. Operational Loading Documents • Fuel index table example F IATA AHM 519 gives information about the kind of information that must appear on a balance chart: A – The type of aircraft and version B – A drawing of the aircraft layout showing : . Vertical or sloping lines corresponding to index variations . according to carriers requirements: H – Index formula for DOW Index calculation(1) I – Weight deviations in galley zones and effect on balance J – Weight information(2) K– Pitch Trim scale for THS setting (1) For a given aircraft. The passenger cabin section . this one can be called a “Load and Trim sheet” 282 Getting to Grips with Aircraft Weight and Balance . it’s possible to start the balance calculation from the Dry Operating Index (DOI) or from the combination DOW / DOW H-arm. (2) When this information appears on the balance chart.LOADING OPERATIONS C. the index formula is only required for the second case. It can be provided on a separate fuel index table G – Final ZFW and TOW CG values in percentage of the Mean Aerodynamic Chord (%MAC). Arrows indicating direction and value of each pitch E – A balance diagram with shaded areas outside the forward and aft balance limits F – The influence of fuel on weight and balance. 378 m Weight deviations : Zone E : +150 kg Zone F : +150 kg Zone G : +200 kg Cargo distribution : Cargo 1 : 3 500 kg Cargo 2 : 4 000 kg Cargo 3 : 7 000 kg Cargo 4 : 5 500 kg Cargo 5 : 750 kg Pax distribution : Cabin OA : 15 pax Cabin OB : 120 pax Cabin OC : 105 pax Fuel data : Takeoff fuel : 54 000 kg Fuel density : 0.C.79 kg/l ⇐ ⇐ ⇐ ⇐ ⇐ Data coming from the weighing report (refer to WBM) Pantry adjustment in the galley zones if not included in DOW Deadload distribution in the cargo holds Passengers distribution in the cabin sections Fuel on board at takeoff and fuel density Getting to Grips with Aircraft Weight and Balance 283 LOADING OPERATIONS . Operational Loading Documents • Numerical example: DOW conditions: Weight : 123 500 kg H-arm : 33. 9% 218 910 kg 164 910 kg 2 8 5 28.5 Jones 240 AI523 CDG JFK 123 500 kg 500 kg 124 000 kg 20 750 kg 20 160 kg 164 910 kg 54 000 kg 218 910 kg +150+150 +150+200 -0.5 % 3.25° UP 164 9 2 9 9 284 Getting to Grips with Aircraft Weight and Balance . Operational Loading Documents 12 FEB 2001 123 500 33.5% 29.247 3500 4000 7000 5500 750 15 120 105 -1 105.378 105.LOADING OPERATIONS C.2 28. I – Index formula for DOW Index calculation As for the balance chart. • Numerical example DOI : 105 CPT2 : 4000 kg CAB ZONE C : 105 pax ZFW Index : 105 – 8 + 19 = 116 Getting to Grips with Aircraft Weight and Balance 285 LOADING OPERATIONS . Operational Loading Documents 5. such as the Index formula for DOW Index calculation (I). optional information may appear on the balance table according to carriers requirements.C. Balance table a) Standard balance table In a balance table. instead of graphical scales as in a balance chart. The position and numbering of holds and compartments C – Tabulated index corrections for each passenger cabin section D – Tabulated index corrections for each cargo compartment E – A balance diagram with shaded areas outside the forward and aft balance limits F – A balance diagram with shaded areas outside the forward and aft balance limits G – The influence of fuel on weight and balance. the index corrections due to a load in a cargo compartment or passengers in a cabin section are indicated thanks to tables.2.2. The passenger cabin section . IATA AHM 519 gives information about the kind of information that must appear on a balance table (refer to next page): A – The type of aircraft and version B – A drawing of the aircraft layout showing : . The user has to start from the DOW Index and then add or subtract the different index corrections to get the ZFW Index. It can be provided on a separate fuel index table (identical to the one used with a balance chart) H – Final ZFW and TOW CG values in percentage of the Mean Aerodynamic Chord (%MAC). LOADING OPERATIONS C. Operational Loading Documents • Balance table example A B I C D E G H F 286 Getting to Grips with Aircraft Weight and Balance . • Complement of 1000 .2) consistent with the index scale.2 DOI CPT 1 CPT 4 CPT 5 CAB OA CAB OB CAB OC ZFW Index 3 The thousands figure is suppressed to obtain a final ZFW Index (514. instead of –3. In this case. Getting to Grips with Aircraft Weight and Balance 287 LOADING OPERATIONS .C.example • Numerical example : 510 : 2000 kg : 1500 kg : 300 kg : 4 pax : 7 pax : 10 pax : 2. As an example. carriers sometimes prefer to use a balance table with complement of 1000.514. the index correction would be 997 (1000-3). index corrections are always positive. Operational Loading Documents b) Balance table with complement of 1000 To avoid negative index corrections that could be a source of mistake. 3.8% WEIGHT DEST CG TOW CG : 30.79 kg/liter Cabin OA : 16 pax Cabin OB : 120 pax Cabin OC : 84 pax UNDERLOAD BEFORE LMC 13560 LMC TOTAL *********************************************************************************** 288 Getting to Grips with Aircraft Weight and Balance .C84 CABIN AREA TRIM DOW Index : 105 MAX 180000 ZFW Index : 118 TOW Index : 117 LAST MINUTE CHANGES ZFW SPEC :CL/CPT MAC 32.B120. • Balance information on an EDP loadsheet – Example CHECKED A/C REG OOTPA APPROVED VERSION C18Y264 CREW 2/9 DATE 30DEC00 EDNO 02 TIME 1405 LOADSHEET ALL WEIGHTS IN KILOS FROM/TO CDG JFK FLIGHT AI0533 LOAD IN COMPARTMENTS PASSENGER/CABIN BAG WEIGHT 10785 DISTRIBUTION 1/3830 2/6955 4/4300 TTL 220 SOC BLKD CAB 16905 190/ 27/ 3 PAX CY 16/204 27690 123250 150940 65500 216440 58600 157840 ************************************************************************* TOTAL TRAFFIC LOAD DRY OPERATING WEIGHT ZERO FUEL WEIGHT TAKE OFF FUEL TAKE OFF WEIGHT ACTUAL TRIP FUEL LANDING WEIGHT ACTUAL MAX 168000 BALANCE INFORMATION (AHM 050) MAX 230000 BALANCE AND SEATING CONDITIONS DOI 105 LIZFW 118 LITOW 117 MACZFW 32.LOADING OPERATIONS C.2 NOSE UP BASED ON FUEL DENSITY .2º NOSE UP Fuel density : 0. and forbid the print out of the loadsheet when the limits are exceeded.8 MACTOW 30. Operational Loading Documents 5.5% MAC THS setting : 2.5 STAB TO 2. The system should be able to check the weight and balance limitations. EDP balance calculation methods The balance information shall be printed on EDP loadsheet or ACARS loadsheet in a specific box called “Balance and seating condition” according to the carrier requirement as per AHM 560.790 KG/LTR A16. 8% MAC : 30.5% MAC Getting to Grips with Aircraft Weight and Balance 289 LOADING OPERATIONS .Example LOADSHEET FINAL 1505 AI05333/30 30DEC00 CDG JFK OOTPA 2/9 ZFW 150940 MAX 168000 TOF 65500 TOW 216440 MAX 230000 TIF 58600 LAW 157840 MAX 180000 UNDLD 13560 PAX /0/16/204 TTL220 LIZFW 118 LITOW 117 MACZFW 32.C.5 ENDAI0533 BALANCE INFORMATION (AHM 050) ZFW Index TOW Index ZFW CG TOW CG : 118 : 117 : 32.8 MACTOW 30. Operational Loading Documents • Balance information on an ACARS loadsheet .