JT15D ATA 73

Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL Page 1 of 22 FOR TRAINING PURPOSES ONLY © JT15D - ISSUE 1, 2009 Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL ATA 73– ENGINE FUEL AND CONTROL 0 TABLE OF CONTENTS 1 1.1 1.2 1.3 1.4 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 3 3.1 3.2 3.3 3.4 3.5 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 5.1 5.2 5.3 5.4 5.5 5.6 Fuel system Purpose Fuel system components Fuel additives and limitations Input requirement Fuel pump Purpose Description Typical pump capacity @ 100% N2 Inlet filter Outlet filter Filter bypass valve Maintenance FCU (hydraulic section) Purpose High pressure relief valve Metering valve Bypass valve Motive flow valve FCU (pneumatic section) Purpose Bellows Governor Enrichment valve Back-up valve T2 temperature compensation sensor Step modulator (JT15D-1 and 4 series) Flight idle solenoid (JT15D-5 series) Operation Flow divider Purpose Fuel shut-off and wind milling bypass valve Minimum pressurising and flow divider valve Spill valve Dump valve Operation 4 4 4 5 5 6 6 6 6 6 7 7 7 8 8 8 8 9 9 10 10 10 10 10 10 10 10 11 11 13 13 13 13 14 14 15 Page 2 of 22 FOR TRAINING PURPOSES ONLY © JT15D - ISSUE 1, 2009 3 7.4 Automatic shut-off valve Purpose Construction Operation Maintenance Fuel nozzles Purpose Construction Operation Maintenance 19 19 19 19 19 20 20 20 20 20 Page 3 of 22 FOR TRAINING PURPOSES ONLY © JT15D .2 7.2 6. 2009 .3 6.ISSUE 1.1 7.4 7 7.1 6.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 6 6. Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 1 1.ISSUE 1.1 FUEL SYSTEM Purpose The fuel system provides the engine with clean fuel at the required flow rate to permit control of engine power Supply high pressure fuel to the bleed valve actuator (JT15D-5 series) 1.2 Fuel system components Fuel pump Motive flow valve Bleed valve actuator (Ref ATA 72 Sect 6.4 – JT15D-5 series) FCU Flow meter (airframe supplied) Fuel cooled oil cooler Flow divider valve Automatic shut-off valve Fuel nozzles Page 4 of 22 FOR TRAINING PURPOSES ONLY © JT15D . 2009 . 4 Input requirements Power lever position P3. high pressure rotor speed Page 5 of 22 FOR TRAINING PURPOSES ONLY © JT15D .Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 1. 2009 .3 Fuel.ISSUE 1. additives and limitation Refer to SB 7144 for complete listing of approved fuel and additives Use of AVGAS limited to 50 hours between any TBO amount of AVGAS Hours operating = average fuel consumption 1. compressor discharge pressure N2. 4 Inlet filter 74 micron metallic type Self bypassing at 9 -12 psid Cleanable Page 6 of 22 FOR TRAINING PURPOSES ONLY © JT15D . and a gear-type second stage (JT15D-5 series) Two filter elements protect downstream components against contamination A bypass valve allows unfiltered fuel to flow to the engine in the event of filter blockage by allowing fuel to bypass the filter 2.ISSUE 1.2 Description: The pump is a one stage gear-type pump (JT15D-1 and 4 series) The fuel pump is a two-stage pump consisting of a centrifugal first stage. 2. 2009 .3 Typical pump capacity @ 100% N2 3935 pph @ 580 psi (JT15D-1 and 4 series) 4100 pph @ 580 psi (JT15D-5 series) 2.1 FUEL PUMP Purpose Provide clean fuel under pressure to the fuel control unit.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 2 2. 7 Maintenance Inspect and clean inlet filter electrosonicaly every minor airframe inspection Inspect and replace outlet filter every minor airframe inspection Replace pump if fuel leakage is detected Page 7 of 22 FOR TRAINING PURPOSES ONLY © JT15D . 2009 .ISSUE 1.6 Filter bypass valve Ball type bypass valve Open at 40 .Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 2.5 Outlet filter 10 micron Paper type filter Disposable 2.60 psid if filter is restricted 2. 3. JT15D-1 and 4 series Wf (min) Wf (max) JT15D-5 series Wf (min) Wf (max) POSITION UP DOWN POSITION UP DOWN FUEL FLOW 155-160 pph 1600-1640 pph FUEL FLOW 160-165 pph 2170-2260 pph Page 8 of 22 FOR TRAINING PURPOSES ONLY © JT15D .Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 3 3. It opens at 1260 psid. The metering valve is mechanically linked to the pneumatic bellows in the FCU by torque tubes.ISSUE 1. 2009 .3 Metering valve The metering valve travels between a maximum and a minimum fuel flow position and determines the amount of fuel going to the engine fuel nozzles.). spring loaded upwards to W f (min. 3. This valve is normally closed until P1 pressure overcomes the spring tension and allows P1 fuel to dump into Po.1 FCU (HYDRAULIC SECTION) Purpose Provide the engine with the required fuel flow according to the power lever position and P3 pressure.2 High pressure relief valve Prevents build up of excess P1 and P2 pressure in the fuel system. Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 3.P2 differential (delta P) of 15-24 psid. Open at 240 psid to supply P1 pressure to the airframe fuel ejector pump (JT15D-5 series). 3. Page 9 of 22 FOR TRAINING PURPOSES ONLY © JT15D . Actuated by means of a diaphragm and spring. the valve maintains a constant P 1 . 2009 .4 By-pass valve The bypass valve returns fuel in excess of engine requirements to Po.ISSUE 1.5 Motive flow valve Open at 120 psid supply P1 pressure to the airframe fuel ejector pump (JT15D-1 and 4 series). constant when engine anti-ice is selected in order to maintain acceleration time constant.2 Bellows Senses Px and Py air pressures. 4.5 Back-up valve Allow bleeding Py pressure when actual N2 is higher than selected N2 (approx 9%). 2009 .4 Enrichment valve Allows optimisation of engine acceleration. 4. It keeps the P3 pressure Page 10 of 22 FOR TRAINING PURPOSES ONLY © JT15D . 4. Px and Py pressure are boost in order to increase acceleration rate.7 Step modulator (JT15D-1 and 4 series) Fitted to all JT15D-4 and JT15D-1 POST SB 7124. 4.6 T2 Temperature Compensation Sensor Modify the fuel schedule to maintain acceleration constant under any ambient temperature. Above 85% N2 speed.1 FCU (PNEUMATIC SECTION) Purpose The function of the N2 governor is to vary engine compressor speed (N2) in order to obtain the desirable thrust (target N1 speed). Movement of the bellows assembly is transmitted to the metering valve assembly via torque tube assembly.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 4 4.3 Governor Sense N2 speed in order to control the amount of bleed of Px and Py pressure.ISSUE 1. It is energised when ignition is ON. 4. 4. this puts tension on the governor spring. increasing rotation of the governor drive shaft. the governor spring is overcome. An increase in drive shaft rotation causes the flyweights to spread. Py increases in the bellows. NOTE: The T2 compensator is matched with the FCU and must be changed as a set. 4. Page 11 of 22 FOR TRAINING PURPOSES ONLY © JT15D . pivoting the governor lever to open the governor orifice again.ISSUE 1. It causes the governor lever to pivot and restricting Py bleed. the engine speed is maintained constant.9 Operation As the pilot move the power lever. the engine accelerates. As W f increases. Once equilibrium between flyweight force and spring tension is obtained. causing the bellows section to go down.8 Flight idle solenoid (JT15D-5 series) Provide higher idle speed (flight idle) to give better respond time on acceleration. 2009 . As it lifts. which lifts the drive shaft table. therefore increasing W f. This downward motion causes the metering valve to move down.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 4. ISSUE 1. This rapid bleed of Py causes the bellows to travel upwards. 2009 . which in turn causes the metering valve to reduce W f and therefore limit an over speed condition. Page 12 of 22 FOR TRAINING PURPOSES ONLY © JT15D . A variable orifice. This sensor effectively modifies the fuel schedule to maintain engine acceleration constant throughout various outside temperatures. therefore increase the rate of acceleration. The T2 compensator is located under the engine nacelle. This boosts Px pressure going to the bellows.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL Above 85% N2 the enrichment lever pivots. controlled by bimetallic disks in the sensor. 9%). If N2 is higher than selected power lever setting (approx. the governor force opens a back-up valve in addition to opening the governor orifice. which opens the enrichment valve. controls the quantity of Px air bleed to atmosphere. 5.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 5 5. 2009 .2 Fuel shut-off and wind milling bypass valve Prevent fuel to flow to nozzles on cut-off position.ISSUE 1. Permit fuel to bypass if engine is wind milling. 5.3 Minimum pressurising and flow divider valve In the absence of metered fuel pressure.1 FLOW DIVIDER Purpose Divide flow between primary and secondary fuel manifolds and dumps fuel from the manifolds on shutdown. the minimum pressurising valve prevents flow to the fuel nozzles Ensures proper operating fuel pressures within the fuel system during the starting sequence Divides the metered fuel flow between the primary and secondary fuel manifolds Page 13 of 22 FOR TRAINING PURPOSES ONLY © JT15D . Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 5.4 Spill valve Reduces FCU minimum fuel flow to a level suitable for the starting sequence 5.5 Dump valve Purges fuel remaining in fuel nozzles and manifolds during shutdown Page 14 of 22 FOR TRAINING PURPOSES ONLY © JT15D .ISSUE 1. 2009 . 6.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 5. the minimum pressurising valve opens and allows fuel to flow to the dump valve and spill valve. Page 15 of 22 FOR TRAINING PURPOSES ONLY © JT15D . A bleed jet allows a small amount of metered fuel to prime the secondary manifold.6 Operation 5.1 Starting position As the power lever is moved from cut-off to the start/run position. 2009 . Metered fuel pressure causes the dump valve to close at 5 psi and fuel flows to the primary fuel manifold and the bleed jet. When the metered fuel reaches 75 psid.ISSUE 1. the shut-off and wind milling valve allow metered fuel from the FCU to flow inside the flow divider. This reduction of fuel to the primary manifold is necessary to optimise the starting characteristics of the engine.ISSUE 1. the engine begins to accelerate towards idle. the spill valve closes under the influence of the increasing P3 air pressure (30 psi).Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL The spill valve opens and diverts a certain amount of metered fuel into the bypass system. Page 16 of 22 FOR TRAINING PURPOSES ONLY © JT15D . Once combustion takes place. 2009 . 2009 . increased fuel pressure causes the flow divider to open and allow fuel flow to the secondary fuel manifold.6. Page 17 of 22 FOR TRAINING PURPOSES ONLY © JT15D .Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 5.2 Running position When the pilot sets N2 above 60%.ISSUE 1. 3 Shut-off position As metered fuel pressure is cut-off by the shut-off and wind milling valve. Page 18 of 22 FOR TRAINING PURPOSES ONLY © JT15D . 2009 .Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 5.ISSUE 1.6. spring tension acting upon the minimum pressure valve causes it to close off the primary and secondary manifold inlet ports. The lack of fuel pressure within the flow divider also allows the dump valve to open. Fuel remaining in the fuel manifold system drains out of the dump port. which is connected to the airframe waste fuel system. This connects the primary and secondary manifold to the fuel dump port. 6. and between bell crank and no. 4 bearing cover Reset the tripper mechanism when system tripped Page 19 of 22 FOR TRAINING PURPOSES ONLY © JT15D . 4 bearing cover. 4 and 5 series) Purpose Automatically cut off fuel in the event low pressure rotor shafts decoupling. NOTE: An axial displacement of the low pressure turbine shaft of 0. the turbine shaft moves rearward and contacts the automatic shut-off valve plunger located in the no.1 AUTOMATIC SHUT-OFF VALVE (JT15D-1. 6.070" is required to trip valve.4 Maintenance Set gap between tripper and housing.2 Construction Actuator rod and bell crank Wire rope Tripper mechanism Shut-off valve 6.3 Operation In the event of low pressure rotor shafts decoupling. 2009 . This causes the shut-off valve to trip and shut-off the supply of fuel to the nozzles.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 6 6.ISSUE 1. Slots in the sheath allow compressor discharge air to pass through the sheath and over the nozzle tip for cooling the tip and atomisation of the fuel. 2009 .1 FUEL NOZZLES (JT15D-1.2 Construction Dual orifice type 12 nozzle adapters 12 nozzle sheaths 12 nozzle tips 24 transfer tubes 7.3 Operation Two offset slots on the nozzle distributor impart a swirl motion to the fuel which emerges as a finely atomised spray in the combustion chamber.4 Maintenance Flow test at 22 and 60 psi Pressure test for cross manifold leakage at 170 . 7.ISSUE 1. 7.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL 7 7.200 psi Leak test at 500 psi once installed on low turbine support case Page 20 of 22 FOR TRAINING PURPOSES ONLY © JT15D . 4 and 5 series) Purpose Deliver and atomise fuel into the combustion chamber. 2009 .ISSUE 1.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL Page 21 of 22 FOR TRAINING PURPOSES ONLY © JT15D . 2009 .ISSUE 1.Pratt & Whitney JT15D Series (CAT C) ATA 73 – ENGINE FUEL AND CONTROL PAGE INTENTIONALLY LEFT BLANK Page 22 of 22 FOR TRAINING PURPOSES ONLY © JT15D .