B737-300/400 Engines apu

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737-300/400737-300/400ENGINES, AUXILIARY ENGINES, AUXILIARY POWER UNIT (APU)POWER UNIT (APU)

NextNextMain MenuMain Menu QuitQuit

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Engine Instruments-Primary PanelEngine Instruments-Primary Panel

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Engine Instruments-Primary PanelEngine Instruments-Primary PanelREVERSER UNLOCKED Lights:REVERSER UNLOCKED Lights:Illuminated –Illuminated –Indicates the respective engine thrust reverser Indicates the respective engine thrust reverser sleeves are unlocked.sleeves are unlocked.

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Engine Instruments-Primary PanelEngine Instruments-Primary PanelNN11 RPM Indicators: RPM Indicators:• Displays NDisplays N11% RPM for respective engine. % RPM for respective engine. • Analog needle corresponds with rolling Analog needle corresponds with rolling digital display.digital display.

Note: Failure of the NNote: Failure of the N1 1 indicator or the transmitter indicator or the transmitter results in the digital display blanking and the results in the digital display blanking and the needle moving to zero.needle moving to zero.

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Engine Instruments-Primary PanelEngine Instruments-Primary PanelNN11 Cursors: Cursors:With NWith N11 manual set knob pushed in – manual set knob pushed in –• Positioned by FMC.Positioned by FMC.• Based on NBased on N11 limit page and takeoff limit page and takeoff reference page.reference page.

With NWith N11 manual set knob pulled out – manual set knob pulled out –• Displays NDisplays N11 selected by flight deck crew. selected by flight deck crew.

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Engine Instruments-Primary PanelEngine Instruments-Primary PanelNN11 Manual Set Indication Windows: Manual Set Indication Windows:• Set by NSet by N11 manual set knob. manual set knob.• Digital readout of NDigital readout of N11 cursor position. cursor position.• Blank when manual set knob is pushed in.Blank when manual set knob is pushed in.

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Engine Instruments-Primary PanelEngine Instruments-Primary PanelNN11 Warning Lights: Warning Lights:Illuminated –Illuminated –• Indicates the NIndicates the N11 limit has been reached or limit has been reached or

exceeded on respective engine.exceeded on respective engine.• Remains illuminated until NRemains illuminated until N11 is reduced is reduced below the limit.below the limit.

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Engine Instruments-Primary PanelEngine Instruments-Primary PanelNN11 Manual Set Knobs: Manual Set Knobs:Pushed in –Pushed in –• NN1 1 cursor set by FMC based on Ncursor set by FMC based on N1 1 limit page limit page

and takeoff reference page.and takeoff reference page.• Blanks respective NBlanks respective N1 1 manual set indication manual set indication

window.window.

Pulled out –Pulled out –• Disables FMC input signal.Disables FMC input signal.• Rotation sets desired NRotation sets desired N1 1 RPM in the RPM in the respective Nrespective N1 1 manual set indication window manual set indication window

and moves the Nand moves the N1 1 cursor to the corresponding cursor to the corresponding location.location.

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EGT Indicators:EGT Indicators:• Displays engine EGT in Displays engine EGT in °°C.C.• Analog needle corresponds with rolling Analog needle corresponds with rolling digital display.digital display.

Note: Failure of the EGT indicator or the Note: Failure of the EGT indicator or the transmitter results in the digital display blanking transmitter results in the digital display blanking and the needle moving to zero.and the needle moving to zero.

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EGT Warning Lights:EGT Warning Lights:Illuminated –Illuminated –• Indicates the EGT limit has been reached Indicates the EGT limit has been reached or exceeded on respective engine.or exceeded on respective engine.• Remains illuminated until EGT reduced Remains illuminated until EGT reduced below the limit.below the limit.

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NN22 RPM Indicators: RPM Indicators:• Displays NDisplays N22% RPM for respective engine. % RPM for respective engine. • Analog needle corresponds with rolling Analog needle corresponds with rolling digital display.digital display.

Note: Failure of the NNote: Failure of the N2 2 indicator or the transmitter indicator or the transmitter results in the digital display blanking and the results in the digital display blanking and the needle moving to zero.needle moving to zero.

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Warning Lights:Warning Lights:Illuminated –Illuminated –• Indicates the NIndicates the N22 limit has been reached or limit has been reached or

exceeded on respective engine.exceeded on respective engine.• Remains illuminated until NRemains illuminated until N22 reduced reduced below the limit.below the limit.


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FF (Fuel Flow) Indicators:FF (Fuel Flow) Indicators:• Displays rate of fuel flow in pounds per Displays rate of fuel flow in pounds per hour at all times.hour at all times.• Analog needle corresponds with rolling Analog needle corresponds with rolling digital display.digital display.

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Fuel Flow Digital Displays (RATE/USED):Fuel Flow Digital Displays (RATE/USED):• With the fuel flow switch in the RATE position, With the fuel flow switch in the RATE position,

indicates rate of fuel consumption in pounds-indicates rate of fuel consumption in pounds-per-hour X 1000.per-hour X 1000.

• With the fuel flow switch held in the USED With the fuel flow switch held in the USED position, indicates the amount of fuel consumed position, indicates the amount of fuel consumed (in pounds) since last reset.(in pounds) since last reset.

• With the fuel flow switch held in the RESET With the fuel flow switch held in the RESET position, resets display on both fuel flow position, resets display on both fuel flow

indicators to zero.indicators to zero.

Fuel Flow Switch:Fuel Flow Switch:Three position switch, spring-loaded to Three position switch, spring-loaded to RATE position.RATE position.

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Engine Instruments-Secondary PanelEngine Instruments-Secondary Panel

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Engine Instruments-Secondary PanelEngine Instruments-Secondary PanelSTART VALVE OPEN Lights:START VALVE OPEN Lights:Illuminated –Illuminated –Respective engine start valve is open and air is Respective engine start valve is open and air is being supplied to the starter.being supplied to the starter.

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Engine Instruments-Secondary PanelEngine Instruments-Secondary PanelLOW OIL PRESSURE Lights:LOW OIL PRESSURE Lights:Illuminated –Illuminated –Respective engine oil pressure is at or below Respective engine oil pressure is at or below the red radial.the red radial.

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Engine Instruments-Secondary PanelEngine Instruments-Secondary PanelOIL FILTER BYPASS Lights:OIL FILTER BYPASS Lights:Illuminated –Illuminated –Indicates and impending or actual bypass of Indicates and impending or actual bypass of the respective scavenge oil filter.the respective scavenge oil filter.

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OIL PRESS Indicators:OIL PRESS Indicators:Displays engine oil pressure in psi.Displays engine oil pressure in psi.

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Low Oil Pressure Yellow Band:Low Oil Pressure Yellow Band:• Indicates minimum oil pressure limit.Indicates minimum oil pressure limit.• Valid only on the ground with takeoff Valid only on the ground with takeoff thrust set.thrust set.

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OIL TEMP Indicators:OIL TEMP Indicators:Displays engine oil temperature in Displays engine oil temperature in °°C.C.

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OIL QUANTITY Indicators:OIL QUANTITY Indicators:Displays engine oil quantity in gallons.Displays engine oil quantity in gallons.

ENG OIL QTY TEST Switch:ENG OIL QTY TEST Switch:Push –Push –OIL QUANTITY indicators move toward zero.OIL QUANTITY indicators move toward zero.

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VIB (Airborne Vibration Monitors):VIB (Airborne Vibration Monitors):Indicates engine vibration level.Indicates engine vibration level.

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Off Index Mark:Off Index Mark:Indicates system is inoperative if needle is Indicates system is inoperative if needle is pointing to blue line.pointing to blue line.

This concludes the review of the This concludes the review of the Engine Instrument Panels. Engine Instrument Panels.

The next section will discuss various other The next section will discuss various other engine panels and controls.engine panels and controls.

Click Click NextNext to continue. to continue.

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Engine Start PanelEngine Start Panel

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Engine Start PanelEngine Start PanelENGINE START Switches:ENGINE START Switches:GRD –GRD –• Opens start valve.Opens start valve.• Closes engine bleed air valve.Closes engine bleed air valve.• Provides ignition to selected igniter(s) when Provides ignition to selected igniter(s) when

engine start lever is positioned to IDLE.engine start lever is positioned to IDLE.• Switch automatically releases to OFF Switch automatically releases to OFF position at starter cutout.position at starter cutout.

OFF –OFF –Ignition off.Ignition off.

CONT –CONT –Provides ignition to selected igniter(s) when Provides ignition to selected igniter(s) when engine start lever is in IDLE position.engine start lever is in IDLE position.

FLT –FLT –Bypasses ignition select switch and provides Bypasses ignition select switch and provides ignition to both igniters when engine start lever ignition to both igniters when engine start lever is in IDLE position.is in IDLE position.

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Engine Start PanelEngine Start Panel

Ignition Select Switch:Ignition Select Switch:IGN L –IGN L –Selects the left igniter on each engine for use on Selects the left igniter on each engine for use on respective engine.respective engine.

BOTH –BOTH –Selects both igniters on each engine for use on Selects both igniters on each engine for use on respective engine.respective engine.

IGN R –IGN R –Selects the right igniter on each engine for use on Selects the right igniter on each engine for use on respective engine.respective engine.

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Engine PanelEngine Panel

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Engine PanelEngine PanelREVERSER Lights:REVERSER Lights:If Illuminated, one or more of the following three If Illuminated, one or more of the following three non-normalnon-normal scenarios has occurred – scenarios has occurred –• Thrust reverser selector valve or thrust reverser Thrust reverser selector valve or thrust reverser

isolation valve are not in commanded position.isolation valve are not in commanded position.

• Thrust reverser sleeve position sensors on same Thrust reverser sleeve position sensors on same engine are in disagreement. (Example: The left engine are in disagreement. (Example: The left thrust reverser sleeve position sensor on the thrust reverser sleeve position sensor on the No. 1 engine is in disagreement with the right No. 1 engine is in disagreement with the right thrust reverser sleeve position sensor on thrust reverser sleeve position sensor on the the No. 1 engine.)No. 1 engine.)

• Auto-restow circuit has been activated (see Auto-restow circuit has been activated (see slide 66).slide 66).

Note: The REVERSER lights will also Note: The REVERSER lights will also normallynormally illuminate when the thrust reverser sleeves are illuminate when the thrust reverser sleeves are commanded to the stow position (see slide 65).commanded to the stow position (see slide 65).

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Engine PanelEngine PanelPMC (Power Management Control) Switches:PMC (Power Management Control) Switches:ON (white ON in view) –ON (white ON in view) –PMC is selected on.PMC is selected on.

INOP (amber INOP in view) –INOP (amber INOP in view) –PMC is inoperative when engine speed is above PMC is inoperative when engine speed is above 46% N46% N22, or the PMC is selected OFF., or the PMC is selected OFF.

Note: Both PMC switches guarded by a plastic Note: Both PMC switches guarded by a plastic lens cover. Cover is hinged on top to rotate lens cover. Cover is hinged on top to rotate upward.upward.

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Engine PanelEngine PanelLOW IDLE Light:LOW IDLE Light:Illuminated –Illuminated –• The thrust lever for either engine is near idle and The thrust lever for either engine is near idle and

the MEC on either engine is not commanded to the MEC on either engine is not commanded to maintain high idle RPM in flight.maintain high idle RPM in flight.

• The speed of either engine is below 25% NThe speed of either engine is below 25% N11 in in flight.flight.

Note: If an engine start lever is in CUTOFF, the Note: If an engine start lever is in CUTOFF, the light is deactivated.light is deactivated.

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Engine ControlsEngine ControlsForward Thrust Levers:Forward Thrust Levers:• Controls respective engine thrust.Controls respective engine thrust.• Cannot be advanced if the respective reverse Cannot be advanced if the respective reverse

thrust lever is in the deployed position.thrust lever is in the deployed position.

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Engine ControlsEngine ControlsReverse Thrust Levers:Reverse Thrust Levers:• Controls respective engine reverse thrust.Controls respective engine reverse thrust.• Cannot select reverse thrust unless respective Cannot select reverse thrust unless respective

forward thrust lever is at IDLE.forward thrust lever is at IDLE.

Note: Reverse thrust lever is blocked at reverse Note: Reverse thrust lever is blocked at reverse idle position until respective thrust reverser idle position until respective thrust reverser sleeves are more than 60% deployed.sleeves are more than 60% deployed.

Note: Movement of reverse thrust lever into Note: Movement of reverse thrust lever into reverse thrust engages locking pawl preventing reverse thrust engages locking pawl preventing forward thrust lever movement. Terminating forward thrust lever movement. Terminating reverse thrust removes locking pawl and restores reverse thrust removes locking pawl and restores forward thrust lever movement ability.forward thrust lever movement ability.

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Engine ControlsEngine ControlsEngine Start Levers:Engine Start Levers:IDLE –IDLE –• Energizes the ignition system.Energizes the ignition system.• Electronically opens the engine fuel shutoff Electronically opens the engine fuel shutoff

valve. This valve is attached to the wing front valve. This valve is attached to the wing front spar and located just outboard of the engine spar and located just outboard of the engine pylon.pylon.

• Mechanically opens the MEC fuel shutoff valve.Mechanically opens the MEC fuel shutoff valve.

CUTOFF –CUTOFF –• De-energizes the ignition system.De-energizes the ignition system.• Electronically closes the engine fuel shutoff Electronically closes the engine fuel shutoff

valve.valve.• Mechanically closes the MEC fuel shutoff valve.Mechanically closes the MEC fuel shutoff valve.

This concludes the review of Engine Panels and Controls. The next section This concludes the review of Engine Panels and Controls. The next section will discuss the APU panels. Click will discuss the APU panels. Click NextNext to continue. to continue.

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APU PanelAPU Panel

11 11

11 AS INSTALLEDAS INSTALLED

11 11

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APU PanelAPU PanelMAINT/LOW OIL QUANTITY Light:MAINT/LOW OIL QUANTITY Light:Illuminated –Illuminated –APU maintenance problem exists.APU maintenance problem exists.• APU oil quantity may be insufficient for extended APU oil quantity may be insufficient for extended

operations.operations.• APU may still be operated.APU may still be operated.

Note: Light is disarmed when APU switch is OFF.Note: Light is disarmed when APU switch is OFF.


11

11

11

11

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APU PanelAPU PanelLOW OIL PRESSURE Light:LOW OIL PRESSURE Light:Illuminated –Illuminated –• Oil pressure is low, therefore initiating an Oil pressure is low, therefore initiating an

automatic shutdown of the APU (after start cycle automatic shutdown of the APU (after start cycle is complete).is complete).

• During start, light is normally illuminated until During start, light is normally illuminated until sufficient oil pressure is achieved.sufficient oil pressure is achieved.



11

11

11

11

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APU PanelAPU PanelFAULT/HIGH OIL TEMP Light:FAULT/HIGH OIL TEMP Light:Illuminated –Illuminated –• Oil temperature is excessive, therefore initiating Oil temperature is excessive, therefore initiating

an automatic shutdown of the APU.an automatic shutdown of the APU.



11

11

11

11

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APU PanelAPU PanelOVERSPEED Light:OVERSPEED Light:Illuminated –Illuminated –• APU RPM limit (110%) has been exceeded, APU RPM limit (110%) has been exceeded,

therefore initiating an automatic shutdown of therefore initiating an automatic shutdown of the APU.the APU.

• APU start has been manually aborted prior to APU start has been manually aborted prior to reaching its governed speed of 100%. When a reaching its governed speed of 100%. When a re-start is attempted, light will extinguish re-start is attempted, light will extinguish

following a normal start.following a normal start.• During a normal shutdown, the overspeed During a normal shutdown, the overspeed

shutdown protection feature has failed its self-shutdown protection feature has failed its self-test.test.



11

11

11

11

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APU PanelAPU PanelEGT Indicator:EGT Indicator:Displays APU EGT.Displays APU EGT.


11

11

11

11

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APU PanelAPU PanelAPU AMPS (APU Generator AC Ammeter):APU AMPS (APU Generator AC Ammeter):Displays APU generator current load.Displays APU generator current load.


11

11

11

11

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APU SwitchAPU SwitchAPU Switch:APU Switch:OFF –OFF –Normal position when APU is not operating.Normal position when APU is not operating.Positioning the switch from ON to OFF while the Positioning the switch from ON to OFF while the APU is operating will accomplish the following:APU is operating will accomplish the following:• Initiates an APU shutdown.Initiates an APU shutdown.• Closes the APU fuel shutoff valve and the APU Closes the APU fuel shutoff valve and the APU

fuel solenoid valve.fuel solenoid valve.• Disconnects the APU from the generator Disconnects the APU from the generator bus(es), bus(es), if connected.if connected.• Closes the APU bleed air valve.Closes the APU bleed air valve.• Closes the APU air inlet door.Closes the APU air inlet door.

ON –ON –Normal position when APU is operating.Normal position when APU is operating.

START (momentary) –START (momentary) –Initiates an automatic start sequence when Initiates an automatic start sequence when momentarily positioning the switch from OFF to momentarily positioning the switch from OFF to START, and then releasing it back to the ON START, and then releasing it back to the ON position.position.

This concludes the review of the This concludes the review of the APU panels. The remainder of the APU panels. The remainder of the

presentation will discuss the engines and APU presentation will discuss the engines and APU in greater detail. Click in greater detail. Click NextNext to continue. to continue.

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EnginesEnginesThe 737-300/400 is powered by two General Electric CFM56-3 engines. The engine is a dual rotor axial The 737-300/400 is powered by two General Electric CFM56-3 engines. The engine is a dual rotor axial flow turbofan of high compression ratio and high bypass ratio. Approximately 20% of the air entering the flow turbofan of high compression ratio and high bypass ratio. Approximately 20% of the air entering the engine inlet is utilized for combustion, while the remaining 80% is bypassed (fan air). The Nengine inlet is utilized for combustion, while the remaining 80% is bypassed (fan air). The N11 rotor rotor consists of a fan and a three stage booster section which is connected by a through shaft to a four stage consists of a fan and a three stage booster section which is connected by a through shaft to a four stage low pressure turbine. The Nlow pressure turbine. The N22 rotor consists of a high pressure compressor and a single stage high rotor consists of a high pressure compressor and a single stage high pressure turbine. The Npressure turbine. The N11 and N and N22 rotors are mechanically independent. rotors are mechanically independent.

CFM56-3CFM56-3

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EnginesEnginesFan Air Fan Air (80%)(80%)

Fan Air Fan Air (80%)(80%)

Air utilized Air utilized for for

combustion combustion (20%)(20%)

The CFM-56 has a high bypass ratioThe CFM-56 has a high bypass ratio

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EnginesEngines

Fan Blades (NFan Blades (N11 rotor) rotor)

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EnginesEngines

Three stage booster section (NThree stage booster section (N11 rotor) rotor)

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EnginesEngines

Four stage low pressure turbine (NFour stage low pressure turbine (N11 rotor) rotor)

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EnginesEngines

Nine stage high pressure compressor (NNine stage high pressure compressor (N2 2 rotor)rotor)

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EnginesEngines

Single stage high pressure turbine (NSingle stage high pressure turbine (N2 2 rotor)rotor)

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EnginesEngines

GearboxGearbox

See pictureSee picturere of re of

gearboxgearbox

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EnginesEngines

Combustion chamberCombustion chamber

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MEC and PMCMEC and PMCThe thrust control system consists of a hydro-mechanical Main Engine Control (MEC) unit and a Power The thrust control system consists of a hydro-mechanical Main Engine Control (MEC) unit and a Power Management Control (PMC) unit mounted on each engine. The PMC is an electronic system with limited Management Control (PMC) unit mounted on each engine. The PMC is an electronic system with limited authority over the MEC. The PMC uses MEC power lever angle, Nauthority over the MEC. The PMC uses MEC power lever angle, N1 1 speed, inlet temperature, and inlet speed, inlet temperature, and inlet pressure to adjust the MEC to obtain the desired Npressure to adjust the MEC to obtain the desired N1 1 speed. The PMC adjusts fuel flow as a function of speed. The PMC adjusts fuel flow as a function of thrust lever angle. The PMC provides a constant thrust climb feature once the thrust lever is set at the thrust lever angle. The PMC provides a constant thrust climb feature once the thrust lever is set at the beginning of climb. Thus, when thrust is set for climb, the PMC automatically maintains that thrust beginning of climb. Thus, when thrust is set for climb, the PMC automatically maintains that thrust throughout the climb profile with no further thrust lever adjustments. If the thrust lever is repositioned, throughout the climb profile with no further thrust lever adjustments. If the thrust lever is repositioned, the PMC maintains the setting corresponding to the new thrust lever angle.the PMC maintains the setting corresponding to the new thrust lever angle.

CFM56-3CFM56-3

See picture of See picture of MEC and PMCMEC and PMC

See picture of See picture of MEC and PMCMEC and PMC

temperature probestemperature probes

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Idle SpeedsIdle SpeedsThere are two engine idle speeds: low idle and high idle.There are two engine idle speeds: low idle and high idle.

• The minimum engine speed for all The minimum engine speed for all flightflight phases is high idle, which varies with flight conditions. As phases is high idle, which varies with flight conditions. As temperature and airspeed decrease, high idle speed also decrease. The average high idle speed is temperature and airspeed decrease, high idle speed also decrease. The average high idle speed is approximately 32% Napproximately 32% N11..

• The minimum engine speed for all The minimum engine speed for all groundground phases is low idle. There is one exception to the previous phases is low idle. There is one exception to the previous sentence: For the first four seconds after touchdown, the engines remain in high idle to enhance sentence: For the first four seconds after touchdown, the engines remain in high idle to enhance

engine engine speed acceleration for reverse thrust, and therefore reduce braking activity. The average low speed acceleration for reverse thrust, and therefore reduce braking activity. The average low idle speed idle speed is approximately 22% Nis approximately 22% N11..

CFM56-3CFM56-3

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Engine SchematicFANAIR

5TH STAGEBLEED AIR

9TH STAGEBLEED AIR

ENGINE IDLE

CONTROL

POWER MANAGEMENT

CONTROL

FLIGHT DECK CONTROLS & INDICATORS

ENGINE FUEL

SYSTEM

AIR DRIVEN STARTER

ENGINE START & IGNITION SYSTEM

ACCESSORIESOIL, FUEL & HYDRAULIC PUMPSGENERATORCSDSTARTERTACHOMETER

FROM PNEUMATIC SYSTEM

FROM FUEL SYSTEM

FROM ENGINE

INDICATING SYSTEM

FROM ELECTRICAL

SYSTEM

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Engine Fuel SystemEngine Fuel SystemFuel is delivered under pressure the from fuel pumps located in the fuel tanks. The fuel enters the engine Fuel is delivered under pressure the from fuel pumps located in the fuel tanks. The fuel enters the engine through the engine fuel shutoff valve. Once through this valve, the fuel passes through the first stage through the engine fuel shutoff valve. Once through this valve, the fuel passes through the first stage engine fuel pump where fuel pressure is increased. It then passes through a fuel/oil heat exchanger engine fuel pump where fuel pressure is increased. It then passes through a fuel/oil heat exchanger where the engine oil heats the fuel. A fuel filter then removes contaminants. (If the fuel filter becomes where the engine oil heats the fuel. A fuel filter then removes contaminants. (If the fuel filter becomes saturated with contaminates, fuel automatically bypasses the fuel filter and continues its flow to the saturated with contaminates, fuel automatically bypasses the fuel filter and continues its flow to the engine. Before this bypass occurs, the FILTER BYPASS light illuminates, which is located on the fuel engine. Before this bypass occurs, the FILTER BYPASS light illuminates, which is located on the fuel panel.) Next, a second stage fuel pump further increases the pressure of the fuel. As the fuel leaves the panel.) Next, a second stage fuel pump further increases the pressure of the fuel. As the fuel leaves the second stage fuel pump, a majority of the fuel passes through another fuel filter an then eventually to the second stage fuel pump, a majority of the fuel passes through another fuel filter an then eventually to the MEC, via the MEC fuel shutoff valve. (The MEC will ensure that the correct amount of fuel is delivered to MEC, via the MEC fuel shutoff valve. (The MEC will ensure that the correct amount of fuel is delivered to the combustion chamber.) However, prior to the MEC, a portion of the fuel is diverted back to the fuel/oil the combustion chamber.) However, prior to the MEC, a portion of the fuel is diverted back to the fuel/oil heat exchanger and then routed to operate the hydro-mechanical portion of the MEC to ensure clean, ice-heat exchanger and then routed to operate the hydro-mechanical portion of the MEC to ensure clean, ice-free fuel for servo operation. free fuel for servo operation.

The engine fuel shutoff valve and MEC fuel shutoff valve allow fuel flow to the engine when both valves The engine fuel shutoff valve and MEC fuel shutoff valve allow fuel flow to the engine when both valves are open. The valves are open when the respective engine fire warning switch is “down” and the are open. The valves are open when the respective engine fire warning switch is “down” and the respective start lever is in the IDLE position. The respective start lever is in the IDLE position. The MEC fuel shutoff valveMEC fuel shutoff valve closes closes onlyonly when the respective when the respective start lever is in the CUTOFF position. The start lever is in the CUTOFF position. The engine fuel shutoff valveengine fuel shutoff valve closes when the start lever is closes when the start lever is positioned back to CUTOFF, or the engine fire warning switch is pulled “up”. The FUEL VALVE CLOSED positioned back to CUTOFF, or the engine fire warning switch is pulled “up”. The FUEL VALVE CLOSED light, located on the fuel panel, indicates the position of the engine fuel shutoff valve. For example, if the light, located on the fuel panel, indicates the position of the engine fuel shutoff valve. For example, if the light glows “dim”, the valve is closed. If the light glows “bright,” the valve is in transit or is in light glows “dim”, the valve is closed. If the light glows “bright,” the valve is in transit or is in disagreement with the switch position. If the light is extinguished, the valve is open.disagreement with the switch position. If the light is extinguished, the valve is open.

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Engine Oil SystemEngine Oil SystemBoth engines have their own oil tank. Oil from the tank is circulated under pressure through the engine Both engines have their own oil tank. Oil from the tank is circulated under pressure through the engine to lubricate the engine bearings and accessory gearbox. Oil quantity is displayed on the oil quantity to lubricate the engine bearings and accessory gearbox. Oil quantity is displayed on the oil quantity indicator.indicator.

The oil system is pressurized by the engine driven oil pump. Oil from the pump is filtered and then flows The oil system is pressurized by the engine driven oil pump. Oil from the pump is filtered and then flows to the engine bearings and gearbox. Sensors for the oil pressure indicator and the LOW OIL PRESSURE to the engine bearings and gearbox. Sensors for the oil pressure indicator and the LOW OIL PRESSURE light are located downstream of the oil filter, prior to engine bearing and gearbox lubrication.light are located downstream of the oil filter, prior to engine bearing and gearbox lubrication.

After lubrication, oil is returned to the oil tank by engine driven scavenge pumps. From the scavenge After lubrication, oil is returned to the oil tank by engine driven scavenge pumps. From the scavenge pumps, oil passes through a scavenge filter. If the scavenge filter becomes saturated with contaminates, pumps, oil passes through a scavenge filter. If the scavenge filter becomes saturated with contaminates, the oil automatically bypasses the filter and continues to flow to the oil tank. Before this bypass occurs, the oil automatically bypasses the filter and continues to flow to the oil tank. Before this bypass occurs, the OIL FILTER BYPASS light illuminates.the OIL FILTER BYPASS light illuminates.

As the oil returns to the tank, oil temperature is sensed and consequently displayed on the oil As the oil returns to the tank, oil temperature is sensed and consequently displayed on the oil temperature indicator. The oil now passes through the fuel/oil heat exchanger, where it is cooled by temperature indicator. The oil now passes through the fuel/oil heat exchanger, where it is cooled by engine fuel prior to returning to the oil tank.engine fuel prior to returning to the oil tank.

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Engine Fuel/Oil Schematic

BC

C

B

ENGINE FUELSHUTOFF VALVE

FUEL / OILHEAT

EXCHANGERFIRST STAGEFUEL PUMP

OILTANK

OILPUMP

OILFILTERIDLE

CONTROL

PMC

MEC FUELSHUTOFF

VALVE

FUELFILTER

FUEL FLOWTRANSMITTER

TO BEARINGS & GEARBOX

FROM FUEL TANK

SCAVENGEPUMPS

SCAVENGEFILTER

SECOND STAGEFUEL PUMP

FUELFILTER

MEC

OILTEMP

OILQUANT

OILPRESS

FUELFLOW

OIL RETURN

B

B

FUELOIL

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Engine Start SystemEngine Start SystemStarter operation requires pressurized air and electrical power. Air from the bleed air system powers the Starter operation requires pressurized air and electrical power. Air from the bleed air system powers the starter motor. Bleed air sources are either the APU, an external ground cart, or the other operating starter motor. Bleed air sources are either the APU, an external ground cart, or the other operating engine.engine.

In the GRD position, the engine start switch uses DC power (from the battery bus) to close the engine In the GRD position, the engine start switch uses DC power (from the battery bus) to close the engine bleed air valve and open the start valve to allow pressure to rotate the starter. When the start valve bleed air valve and open the start valve to allow pressure to rotate the starter. When the start valve opens, the START VALVE OPEN light illuminates. The starter rotates the Nopens, the START VALVE OPEN light illuminates. The starter rotates the N22 high pressure compressor high pressure compressor through the gearbox. When the engine accelerates to the recommended value (25% Nthrough the gearbox. When the engine accelerates to the recommended value (25% N22 or max motoring), or max motoring), moving the engine start lever from the CUTOFF to the IDLE position opens the fuel valves. (The engine moving the engine start lever from the CUTOFF to the IDLE position opens the fuel valves. (The engine fuel shutoff valve is electrically opened and the MEC fuel shutoff valve is mechanically opened.) With fuel shutoff valve is electrically opened and the MEC fuel shutoff valve is mechanically opened.) With both fuel valves now open, the MEC meters the fuel to the combustion chamber where the fuel ignites. At both fuel valves now open, the MEC meters the fuel to the combustion chamber where the fuel ignites. At starter cutout (approximately 46% Nstarter cutout (approximately 46% N22), power is removed from the engine start switch holding solenoid, ), power is removed from the engine start switch holding solenoid, which returns the start switch to the OFF position. Also occurring at starter cutout are: engine bleed air which returns the start switch to the OFF position. Also occurring at starter cutout are: engine bleed air valve returns to the selected position, start valve closes, START VALVE OPEN light extinguishes, and a valve returns to the selected position, start valve closes, START VALVE OPEN light extinguishes, and a rise in pressure can be witnessed on the bleed air duct pressure indicator (respective needle).rise in pressure can be witnessed on the bleed air duct pressure indicator (respective needle).

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Engine Start SystemEngine Start SystemEach engine has two igniters (left and right). The ignition select switch selects either the left, right, or Each engine has two igniters (left and right). The ignition select switch selects either the left, right, or both igniters for both engines. The ignition select switch is bypassed when the engine start switch is in both igniters for both engines. The ignition select switch is bypassed when the engine start switch is in the FLT position.the FLT position.

The left igniter on each engine is powered by its respective AC transfer bus. The right igniter on each The left igniter on each engine is powered by its respective AC transfer bus. The right igniter on each engine is powered by the AC standby bus. Both igniters provide high energy ignition.engine is powered by the AC standby bus. Both igniters provide high energy ignition.

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Start and Ignition SchematicCONDITION:• ENGINE NO. 1 BEING STARTED• N2 ROTATION BELOW STARTER CUTOUT SPEED

NO. 1TRANSFER

BUS

NO. 1 ENGINE

AC STANDBYBUS

FLTCONT

OFFGRD

FLTCONT

OFFGRD

FLTCONT

OFFGRD

STARTSWITCH

HOLDINGRELAY

BATTERYBUS

HIGH N2

LOW N2

STARTERCUTOUTSWITCH

STARTVALVE

S

AIR DRIVENSTARTER ENGINE

BLEEDAIR

VALVE

COMBUSTIONCHAMBER

FROMPNEUMATIC

SYSTEM

MEC

FROMFUEL

SYSTEMNO. 1 START

LEVER INIDLE POSITION

LEFTIGNITER

RIGHTIGNITER

CUTOFF

CUTOFF

IDLE

IDLE

IGN LBOTH

IGN R

IGN LBOTH

IGN R

BLEED AIR

FUEL

Slide 61 of 73

Thrust ReverseThrust ReverseEach engine is equipped with a hydraulically operated thrust reverser, consisting of left and right Each engine is equipped with a hydraulically operated thrust reverser, consisting of left and right translating sleeves. As the reverser sleeves translate aft, ten blocker doors rotate into a blocking translating sleeves. As the reverser sleeves translate aft, ten blocker doors rotate into a blocking position which forces fan air in a reverse direction, through cascade vanes, thereby producing reverse position which forces fan air in a reverse direction, through cascade vanes, thereby producing reverse thrust. The thrust reverser is for ground operations only and is utilized after touchdown to slow the thrust. The thrust reverser is for ground operations only and is utilized after touchdown to slow the aircraft, reducing stopping distance and brake wear.aircraft, reducing stopping distance and brake wear.

Hydraulic pressure for the operation of engine No. 1 and engine No. 2 thrust reversers comes from Hydraulic pressure for the operation of engine No. 1 and engine No. 2 thrust reversers comes from hydraulic systems “A” and “B” respectively. If hydraulic system “A” or “B” fails, alternate operation for hydraulic systems “A” and “B” respectively. If hydraulic system “A” or “B” fails, alternate operation for the affected thrust reverser is available through the standby hydraulic system. When the standby system the affected thrust reverser is available through the standby hydraulic system. When the standby system is being utilized, the affected thrust reverser deploys and retracts at a slower rate, and therefore some is being utilized, the affected thrust reverser deploys and retracts at a slower rate, and therefore some thrust asymmetry can be anticipated.thrust asymmetry can be anticipated.

See picture of See picture of cascade vanescascade vanes

Slide 62 of 73

737-300/400 Hydraulic Schematic (specific to thrust

reverse)

Hydraulic pressure for the

operation of engine No. 1 and

engine No. 2 thrust reversers

comes from hydraulic systems

“A” and “B” respectively. If

hydraulic system “A” or “B” fails,

alternate operation for the affected thrust

reverser is available through

the standby hydraulic system.

“B” system pressure

“A” system pressure

Supply

Standby system pressure

Case drain return

To return

Standby system

reservoir

Motor

Return

To return P P To return

Hydraulic shutoff

No. 1fuel tank

To reservoir Hydraulic heat exchanger

Engine driven pump

Hydraulic shutoff

No. 2fuel tank

To reservoirHydraulic heat exchanger

Motor

Electric pump

Electric pump

Motor

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

Engine driven pump

“B” system

reservoirPneumatic air

Return

Standpipe(quantity 50%)

Standpipe (quantity 0%). 1 gallon remaining for

PTU use only.

No. 2 thrust reverser

No. 1 thrust reverser

Slide 63 of 73

Thrust ReverseThrust ReverseWhen reverse thrust is selected, the isolation valve opens and the thrust reverser control valve moves to When reverse thrust is selected, the isolation valve opens and the thrust reverser control valve moves to the deploy position, thereby allowing hydraulic pressure to unlock and deploy the thrust reverser system. the deploy position, thereby allowing hydraulic pressure to unlock and deploy the thrust reverser system. An interlock mechanism restricts movement of the reverse thrust lever until the reverser sleeves are An interlock mechanism restricts movement of the reverse thrust lever until the reverser sleeves are more than 60% deployed. As the thrust reverser reaches the fully deployed position, the reverse thrust more than 60% deployed. As the thrust reverser reaches the fully deployed position, the reverse thrust lever can be raised to detent No. 2. This position provides adequate reverse thrust for normal operations. lever can be raised to detent No. 2. This position provides adequate reverse thrust for normal operations. When necessary, the reverse thrust lever can be pulled beyond detent No. 2, providing maximum reverse When necessary, the reverse thrust lever can be pulled beyond detent No. 2, providing maximum reverse thrust. When either reverser sleeve moves from the stowed position, the amber REVERSER UNLOCKED thrust. When either reverser sleeve moves from the stowed position, the amber REVERSER UNLOCKED light on the center instrument panel illuminates.light on the center instrument panel illuminates.

Downward motion of the reverse thrust lever past detent No. 1 commands the reverser to stow. Once the Downward motion of the reverse thrust lever past detent No. 1 commands the reverser to stow. Once the thrust reverser is commanded to stow, the control valve moves to the stow position allowing hydraulic thrust reverser is commanded to stow, the control valve moves to the stow position allowing hydraulic pressure to stow and lock the reverser sleeves. After the thrust reverser is stowed, the isolation valve pressure to stow and lock the reverser sleeves. After the thrust reverser is stowed, the isolation valve closes.closes.

Thrust reverser leversThrust reverser levers

Slide 64 of 73

Thrust Reverse SchematicMAXIMUM REVERSE THRUST

DETENT NO. 2

DETENT NO. 1

INTERLOCKSTOWED FORWARD

THRUSTLEVER

REVERSE THRUST (DEPLOYED)REVERSE THRUST (STOWED)SYS. “A”

STBY SYS

SYS “B”

ENGINE NO. 1 SYSTEM “A”HYDRAULICPRESSURE

ENGINE NO. 2 SYSTEM “B”

HYDRAULIC PRESSURE

ISOLATION VALVE(CLOSED)

CONTROL VALVE(STOW)

ACTUATOR(STOWED &

LOCKED)

FAN AIR FLOW

CASCADE VANES TRANSLATING

SLEEVE

ENG.NO. 1SYS“A”

HYD.PRESS.

ENGINE NO. 2SYSTEM “B”

HYDRAULIC PRESSURE

CONTROLVALVE

(DEPLOY)ISOLATION

VALVE(OPEN)

ACTUATOR(DEPLOY)

BLOCKER DOOR

SYS. “A”

STBY SYS

SYS “B”

FAN AIRFLOW

TRANSLATINGSLEEVE

CASCADE VANES

Slide 65 of 73

Thrust ReverseThrust ReverseThe REVERSER lights, located on the aft overhead panel, The REVERSER lights, located on the aft overhead panel, normallynormally illuminate whenever the thrust illuminate whenever the thrust reverser sleeves are commanded to the stow position. In this situation, the REVERSER lights illuminate reverser sleeves are commanded to the stow position. In this situation, the REVERSER lights illuminate because the selector valve has been commanded to the “stow” position, while the isolation valve because the selector valve has been commanded to the “stow” position, while the isolation valve remains “open” to allow hydraulic fluid to flow to the hydraulic actuators which close the translating remains “open” to allow hydraulic fluid to flow to the hydraulic actuators which close the translating sleeves. This is disagreement between the two valves, thereby illuminating the respective REVERSER sleeves. This is disagreement between the two valves, thereby illuminating the respective REVERSER light. The isolation valve will remain “open” for approximately light. The isolation valve will remain “open” for approximately tenten seconds, allowing enough time for the seconds, allowing enough time for the hydraulic actuators to fully stow the thrust reverser sleeves (the MASTER CAUTION and ENG system hydraulic actuators to fully stow the thrust reverser sleeves (the MASTER CAUTION and ENG system annunciator lights are annunciator lights are notnot signaled to illuminate during the ten seconds that the selector valve and signaled to illuminate during the ten seconds that the selector valve and isolation valve are in disagreement). When the thrust reverser sleeves are fully stowed, the isolation isolation valve are in disagreement). When the thrust reverser sleeves are fully stowed, the isolation valve closes and the respective REVERSER light extinguishes.valve closes and the respective REVERSER light extinguishes. If a REVERSER light remains illuminated for more than approximately If a REVERSER light remains illuminated for more than approximately twelvetwelve seconds, a malfunction has seconds, a malfunction has occurred and the MASTER CAUTION and ENG system annunciator lights now illuminate.occurred and the MASTER CAUTION and ENG system annunciator lights now illuminate.

Slide 66 of 73

Thrust ReverseThrust ReverseAn auto-restow circuit compares An auto-restow circuit compares actualactual thrust reverser sleeve position to the thrust reverser sleeve position to the commandedcommanded thrust reverser thrust reverser sleeve position. In the event of an incomplete stowage or un-commanded movement of the thrust sleeve position. In the event of an incomplete stowage or un-commanded movement of the thrust reverser sleeves toward the deployed position, the auto-restow circuit opens the isolation valve and reverser sleeves toward the deployed position, the auto-restow circuit opens the isolation valve and commands the control valve to the stow position, thereby directing hydraulic pressure to stow the thrust commands the control valve to the stow position, thereby directing hydraulic pressure to stow the thrust reverser sleeves. This will result in the illumination of the respective REVERSER light.reverser sleeves. This will result in the illumination of the respective REVERSER light.

Once the auto-restow circuit is activated, the isolation valve remains open and the control valve is held in Once the auto-restow circuit is activated, the isolation valve remains open and the control valve is held in the stowed position until the thrust reverser is commanded to deploy or until corrective maintenance the stowed position until the thrust reverser is commanded to deploy or until corrective maintenance action is taken.action is taken.

Slide 67 of 73

APUThe Auxiliary Power Unit (APU) is a self-contained gas turbine engine consisting of a compressor, turbine, and accessory drive section. It is installed within a fireproof compartment located in the tail of the aircraft. Gear driven units in the accessory drive section control the APU from startup to shutdown. The APU can be operated up to the aircraft maximum certified altitude.

The APU supplies bleed air for engine starting and air conditioning. In flight or on the ground, the APU can supply bleed air to one air conditioning pack.

An AC electrical generator on the APU provides an auxiliary AC power source. While on the ground, both generator bus 1 and generator bus 2 can be powered from the APU. In flight, only one generator bus can be powered from the APU.

EXHAUST OUTLET

EXHAUST MUFFLER

APU FUEL LINE

ACCESSORY COOLING AIR DUCT

APU DUCT

AIR DIFFUSER DUCT

VORTEX GENERATOR

AIR INLET DOOR

APU BLEED AIR DUCT

Slide 68 of 73

APUWhen the AC powered fuel pumps are operating, fuel to start and operate the APU comes from the left side of the fuel manifold. If the fuel pumps are not operating, fuel is suction fed from the No. 1 fuel tank. During APU operating, fuel is automatically heated to prevent icing.

APU engine air is routed to the APU through an automatically operated air inlet door located on the right side of the fuselage. APU exhaust gases are discharged overboard through an exhaust muffler. A portion of the air entering the air inlet door is drawn in by a gear driven fan and then routed to cool the electrical generator and engine oil.

EXHAUST OUTLET

EXHAUST MUFFLER

APU FUEL LINE


APU DUCT

AIR DIFFUSER DUCT

VORTEX GENERATOR

AIR INLET DOOR

APU BLEED AIR DUCT

Slide 69 of 73

APUAPU operation requires the following:• APU fire handle on the overheat/fire panel must be “down”.• APU fire control handle on the APU ground control panel must be “up”.• Battery (BAT) switch must be ON.

Electrical power to start the APU comes from the aircraft battery.

While on the ground, if the battery (BAT) switch is positioned to OFF, the APU will shutdown due to the loss of power to the APU fire detector loop.

EXHAUST OUTLET

EXHAUST MUFFLER

APU FUEL LINE


APU DUCT

AIR DIFFUSER DUCT

VORTEX GENERATOR

AIR INLET DOOR

APU BLEED AIR DUCT

Slide 70 of 73

APUAPUThe automatic start sequence begins by moving the APU start switch momentarily to the START position. The automatic start sequence begins by moving the APU start switch momentarily to the START position. This initiates opening of the APU fuel shutoff valve (located in the wheel well) and the air inlet door. This initiates opening of the APU fuel shutoff valve (located in the wheel well) and the air inlet door. When the air inlet door is fully open, the start sequence begins. If the APU does not reach the proper When the air inlet door is fully open, the start sequence begins. If the APU does not reach the proper speed with the proper acceleration rate within the time limit of the starter, the start cycle automatically speed with the proper acceleration rate within the time limit of the starter, the start cycle automatically terminates. The start cycle may take as long as 135 seconds.terminates. The start cycle may take as long as 135 seconds.

When the APU reaches the proper speed, ignition and fuel are provided for combustion. When the APU is When the APU reaches the proper speed, ignition and fuel are provided for combustion. When the APU is ready to accept a bleed air or electrical load, the APU GEN OFF BUS light illuminates.ready to accept a bleed air or electrical load, the APU GEN OFF BUS light illuminates.

It is recommended that the APU be operated for at least one full minute before utilizing as a bleed source. It is recommended that the APU be operated for at least one full minute before utilizing as a bleed source. This one minute stabilization period is to extend the service life of the APU. This one minute stabilization period is to extend the service life of the APU.

Slide 71 of 73

APUAPUThe APU will automatically shutdown if it encounters LOW OIL PRESSURE, HIGH OIL TEMP (FAULT), The APU will automatically shutdown if it encounters LOW OIL PRESSURE, HIGH OIL TEMP (FAULT), OVERSPEED or a FIRE. These four auto-shutdown features stop the operation of the APU by closing the OVERSPEED or a FIRE. These four auto-shutdown features stop the operation of the APU by closing the fuel solenoid valve, which is attached to the APU fuel control unit.fuel solenoid valve, which is attached to the APU fuel control unit.

A combination of electrical loads and bleed air extraction may cause the EGT to rise above acceptable A combination of electrical loads and bleed air extraction may cause the EGT to rise above acceptable levels. In this scenario, the APU bleed valve will automatically modulate towards the closed position, levels. In this scenario, the APU bleed valve will automatically modulate towards the closed position, which will result in a lower EGT.which will result in a lower EGT.


11 11

11 11

Slide 72 of 73

APU Engine Cross Section

A) Output shaftB) Inlet plenumC) First stage compressorD) Second stage compressorE) Turbine plenumF) Bleed air valveG) Fuel nozzleH) IgniterI) CombustorJ) Turbine

A

BC D

E

F

GH

I

J

Accessorysection

Compressorsection

Turbinesection

Slide 73 of 73

APU SchematicNO. 1

FUEL TANK

FUELSHUTOFF

VALVE

M

3-WAYCONTROL

VALVE

S FUEL SOLENOIDVALVE

OVERBOARD

TO ELECTRICALLOADS

FCU

GENERATOR

SPEED SWITCH

OIL COOLER

OIL PUMPSTARTER

AC

CES

SOR

Y G

EAR

BO

X

ACCELERATION / LOAD CONTROL THERMOSTAT

TURBINE COMPRESSOR

IGNITER

BLEEDAIR VALVE

FUEL PUMP

SPEED CONTROL

ACCELERATIONCONTROL

M

AIR INLETDOOR

TO BLEEDLOADSFUEL

APU BLEED AIR

APU CONTROL AIR

RAM AIR

1 AS INSTALLED

1

1

PT. METRO BATAVIAPT. METRO BATAVIADirectorate of OperationalDirectorate of Operational

Engineering

B737-300/400 Engines apu