b737-300/400 hydraulics

of 69PT. METRO BATAVIAPT. METRO BATAVIADirectorate of OperationalDirectorate of Operational

737-300/400737-300/400HYDRAULICSHYDRAULICS

NextNextMain MenuMain Menu QuitQuit


737-300/400 Hydraulic Schematic

“B” system pressure

“A” system pressure

Supply

Standby system pressure

Case drain return

“A” system

reservoir

Pneumatic air

Return

Engine driven pump

Standpipe(quantity 25%)

Hydraulic shutoff

No. 1fuel tank

To reservoir Hydraulic heat exchanger

Motor

Electric pump

To return P

Standby rudder

Ground spoilers

Nose wheel steering

Alternate brakes

PAccumulator isolation valve

Alternate nose wheel steering

Trailing edge flaps

Alternate Brakes Selector Valve

Autobrake control module

Aileron

Rudder

Elevator and Elevator feelAutopilot B &

yaw damper

Leading edge devices standby extension

If installed

“B” system

reservoirPneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank

To reservoirHydraulic heat exchanger

Motor

Electric pump

P To return

Hydraulic brake pressure accumulator

Autoslat operationLeading edge flaps & slats

“A” Motor

“B” Pump

Power Transfer Unit (PTU)

Standpipe (quantity 0%). 1 gallon remaining for

PTU use only.

Return

Standby system

reservoir

Motor

To return

PTU control valve

50%

Autopilot A

Normal brakes

Landing gear transfer unit

Landing gear

No. 1 thrust reverser


Outboard flight spoilersInboard flight

spoilers



The “A” system reservoir is

pressurized with pneumatic air

from either side of the pneumatic

manifold, and has a capacity of 4.8

U.S. gallons.



Supply


Case drain return

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)



One “A” system engine-driven

pump, mounted to the lower left side

of the No. 1 engine, delivers

approximately 22 gallons per

minute at 3000 psi.



Supply


Case drain return

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)



One “A” system electric motor-driven pump,

mounted in the main wheel well,

delivers approximately six

gallons per minute at

2700 psi. “B”

system pressure


Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)



There are two overheat sensors

for the “A” system electric motor-driven

pump; one in the motor, and one in

the case drain line. One

hydraulic heat exchanger,

located in the No. 1 fuel tank, utilizes fuel to

cool the hydraulic fluid returning to the reservoir from

the two pumps.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank




There is one low pressure light for each ”A” system hydraulic pump. The low pressure

sensors are located upstream of their respective

check valve. Total “A” system pressure is read downstream of

both check valves.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank


To return P



The Power Transfer Unit (PTU) is an

alternate source of power to the

autoslat system.

Please see the Flight Controls

presentation for a detailed

description of the PTU.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank


To return P “A” Motor

“B” Pump


PTU control valve



The No. 1 thrust reverser is

powered by “A” system

hydraulics.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve




The “A” system works in

conjunction with the “B” system to

operate the primary flight

controls.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder

Elevator and Elevator feel



Autopilot “A” is powered by “A”

system hydraulics.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder

Elevator and Elevator feelAutopilot “A”



The two inboard flight spoilers are powered by “A”

system hydraulics.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder


Inboard flight spoilers



The alternate brakes are


hydraulics.



Supply


Case drain return

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Accumulator isolation valve



The six ground spoilers are


hydraulics.



Supply


Case drain return

Ground spoilers

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes





Normal extension and retraction of the landing gear is accomplished via “A” system

hydraulics.

Please see the Landing Gear


description of the landing gear transfer unit.



Supply


Case drain return


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers




Nose wheel steering is normally

controlled by “A” system

hydraulics.



Supply


Case drain return

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers




The “B” system reservoir is

pressurized with pneumatic air

from either side of the pneumatic

manifold, and has a capacity of 7.2

U.S. gallons.



Supply


Case drain return

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.



One “B” system engine-driven

pump, mounted to the lower left side

of the No. 2 engine, delivers

approximately 22 gallons per

minute at 3000 psi.



Supply


Case drain return

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.



One “B” system electric motor-driven pump,

mounted in the main wheel well,

delivers approximately six

gallons per minute at

2700 psi.“B”

system pressure


Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.



There are two overheat sensors

for the “B” system electric motor-driven

pump; one in the motor, and one in

the case drain line. One

hydraulic heat exchanger,

located in the No. 2 fuel tank, utilizes fuel to

cool the hydraulic fluid returning to the reservoir from

the two pumps.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank




There is one low pressure light for each ”B” system hydraulic pump. The low pressure

sensors are located upstream of their respective

check valve. Total “B” system pressure is read downstream of

both check valves.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank


P To return



Normal autoslat and leading edge

flaps & slats operation is from

“B” system hydraulics.

Recall that the Power Transfer Unit (PTU) is an alternate source of power to the

autoslat system.

Please see the Flight Controls


description of the PTU.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank


P To returnAutoslat operation

Leading edge flaps & slats



The No. 2 thrust reverser is

powered by “B” system

hydraulics.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







The “B” system works in

conjunction with the “A” system to

operate the primary flight

controls.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







Autopilot “B” is powered by “B”

system hydraulics.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank





Autopilot “B” & yaw damper



The two outboard flight spoilers are powered by “B”

system hydraulics.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank






Outboard flight spoilers



Both normal and accumulator brakes are

powered by “B” system

hydraulics.



Supply


Case drain return

Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P

Hydraulic brake pressure accumulatorNormal

brakes



Autobrakes are powered by “B”

system hydraulics.



Supply


Case drain return


Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes



The trailing edge flaps are powered

by “B” system hydraulics.



Supply


Case drain return


Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps



Under certain conditions, the “B” system will

retract the landing gear via the landing gear transfer unit.

Please see the Landing Gear


description of the landing gear transfer unit.



Supply


Case drain return


Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps



As an alternate source of power, the “B” system will operate the

nose wheel steering, if an alternate nose wheel steering

switch is installed.



Supply


Case drain return

If installed



Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps



The standby reservoir is

mounted on the keel beam in the main gear wheel well and has a capacity of 2.8 U.S. gallons. A

balance line connects the

standby reservoir to the “B” system

reservoir.



Supply


Case drain return

If installed



Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps

Return

Standby system

reservoir

50%



The standby system electric motor-driven

pump is mounted aft of the standby reservoir on the keel beam. The pump delivers approximately

three gallons per minute at

3000 psi. “B”

system pressure


Supply


Case drain return

If installed



Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps

Standby system

reservoir

Return

50%

To return

Motor



As an alternate source of power,

the standby system can

extend, but not retract, the

leading edge devices.

Please see the Flight Controls presentation for

additional information on the alternate method of extending the

leading edge devices.



Supply


Case drain return

If installed



Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps

Standby system

reservoir

Return

50%

To return

Motor





the standby system can operate the

rudder when certain conditions

exist.

In addition to this presentation, please see the Flight Controls presentation for

more information on when the

standby system will act as an

alternate power source to the

rudder.



Supply


Case drain return

If installed



Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps

Standby system

reservoir

Return

50%

To return

Motor


Standby rudder




the standby system can

operate the thrust reversers if

normal hydraulic pressure is lost.

Please see the Engines/APU


description of the thrust

reverser system.



Supply


Case drain return

If installed



Motor

Electric pump

Engine driven pump

Hydraulic shutoff

Nose wheel steering


Landing gear

Electric pump

Motor

Hydraulic shutoff

Engine driven pump

“A” system

reservoir

Pneumatic air

ReturnStandpipe

(quantity 25%)

No. 1fuel tank



“B” Pump


PTU control valve


Aileron

Rudder



Alternate brakes


Ground spoilers


“B” system


Return



PTU use only.

No. 2fuel tank







P


brakes

Trailing edge flaps

Standby system

reservoir

Return

50%

To return

Motor


Standby rudder

This concludes the review of the Hydraulic Schematic. The next section This concludes the review of the Hydraulic Schematic. The next section will discuss the Hydraulic Panels and Indicators. Click will discuss the Hydraulic Panels and Indicators. Click NextNext to continue. to continue.


Hydraulic PanelHydraulic Panel



Associated lights and Associated lights and switches for the “A” switches for the “A”

hydraulic systemhydraulic system

Associated lights and Associated lights and switches for the “B” switches for the “B”

hydraulic systemhydraulic system



Engine Hydraulic Pump (HYD PUMPS) Switches:Engine Hydraulic Pump (HYD PUMPS) Switches:ON –ON –De-energizes the pump depressurizing solenoid, De-energizes the pump depressurizing solenoid, which results in repositioning of a blocking valve which results in repositioning of a blocking valve to allow pump pressure to enter system.to allow pump pressure to enter system.

OFF –OFF –Energizes the pump depressurizing solenoid, Energizes the pump depressurizing solenoid, which results in repositioning of a blocking valve which results in repositioning of a blocking valve to block pump output.to block pump output.

Note: It is recommended that the engine Note: It is recommended that the engine hydraulic pump switches remain ON at shutdown hydraulic pump switches remain ON at shutdown to prolong the service life of the depressurizing to prolong the service life of the depressurizing solenoid.solenoid.



Electric Hydraulic Pump (HYD PUMPS) Switches:Electric Hydraulic Pump (HYD PUMPS) Switches:ON –ON –Provides electrical power to the associated Provides electrical power to the associated electric motor-driven pump. electric motor-driven pump.

OFF –OFF –Electrical power removed from the pump.Electrical power removed from the pump.

Note: The power source for the “A” hydraulic Note: The power source for the “A” hydraulic system electric pump is generator bus 2. The system electric pump is generator bus 2. The power source for the “B” hydraulic system power source for the “B” hydraulic system electric pump is generator bus 1.electric pump is generator bus 1.



Electric Hydraulic Pump OVERHEAT Lights:Electric Hydraulic Pump OVERHEAT Lights:Illuminated –Illuminated –Associated electric motor-driven pump has Associated electric motor-driven pump has overheated. From case drain return 225 – 265 overheated. From case drain return 225 – 265 degree F and From Pump or Case drain 235 – degree F and From Pump or Case drain 235 – 275 degree F275 degree F



Hydraulic Pump LOW PRESSURE Lights:Hydraulic Pump LOW PRESSURE Lights:Illuminated –Illuminated –Output pressure of associated pump is low < Output pressure of associated pump is low < 1300 PSI1300 PSI

Note: When an engine fire warning switch is Note: When an engine fire warning switch is “pulled-up,” the associated “pulled-up,” the associated engine-driven pumpengine-driven pump LOW PRESSURE light is deactivated. For LOW PRESSURE light is deactivated. For example, pulling up on the No. 1 engine fire example, pulling up on the No. 1 engine fire warning switch will result in a loss of hydraulic warning switch will result in a loss of hydraulic fluid flow to the “A” system engine-driven pump fluid flow to the “A” system engine-driven pump and more importantly, an engine shutdown. and more importantly, an engine shutdown. Therefore, in order to eliminate a nuisance light, Therefore, in order to eliminate a nuisance light, the LOW PRESSURE light for the “A” system the LOW PRESSURE light for the “A” system engine-driven pump is deactivated.engine-driven pump is deactivated.

Please see the Fire Protection presentation for a Please see the Fire Protection presentation for a list of items that occur when an engine fire list of items that occur when an engine fire warning switch is “pulled-up.”warning switch is “pulled-up.”


Standby HydraulicsStandby HydraulicsLights and Associated Switches are Located on the top-half of the Lights and Associated Switches are Located on the top-half of the

Flight Control PanelFlight Control Panel




STANDBY HYD LOW QUANTITY Light:STANDBY HYD LOW QUANTITY Light:Illuminated –Illuminated –Indicates low quantity in standby hydraulic Indicates low quantity in standby hydraulic reservoir (approximately 50%) or 1,4 USGreservoir (approximately 50%) or 1,4 USG

Note: This light is always armed.Note: This light is always armed.

STANDBY HYD LOW PRESSURE Light:STANDBY HYD LOW PRESSURE Light:Illuminated –Illuminated –Indicates output pressure of standby pump is Indicates output pressure of standby pump is low < 1300 PSIlow < 1300 PSI

Note: This light is armed only when Note: This light is armed only when standby pump operation has been standby pump operation has been selected or automatic standby function selected or automatic standby function is activated.is activated.




FLT CONTROL Switches:FLT CONTROL Switches:STBY RUD –STBY RUD –Activates standby pump and opens standby Activates standby pump and opens standby rudder shutoff valve to pressurize standby rudder rudder shutoff valve to pressurize standby rudder power control unit.power control unit.

OFF –OFF –Closes flight control shutoff valve isolating Closes flight control shutoff valve isolating ailerons, elevators, and rudder from associated ailerons, elevators, and rudder from associated hydraulic system pressure.hydraulic system pressure.

ON (guarded position) –ON (guarded position) –Normal operating position.Normal operating position.




FLT CONTROL LOW PRESSURE Lights:FLT CONTROL LOW PRESSURE Lights:Illuminated –Illuminated –• Indicates low hydraulic system ("A" or “B”) Indicates low hydraulic system ("A" or “B”)

pressure to ailerons, elevator, and rudder.pressure to ailerons, elevator, and rudder.• Deactivated when associated FLIGHT CONTROL Deactivated when associated FLIGHT CONTROL

switch is switch is positioned to STBY RUD positioned to STBY RUD andand standby standby rudder shutoff valve is fully rudder shutoff valve is fully open.open.• On airplanes with the rudder pressure reducer On airplanes with the rudder pressure reducer

installed, the “A” system light indicates “A” installed, the “A” system light indicates “A” system pressure is low when normal system system pressure is low when normal system pressure is commanded.pressure is commanded.

• Light GOES OFF after FLT CONTROL switch Light GOES OFF after FLT CONTROL switch selected to STBY RUDselected to STBY RUD




ALTERNATE FLAPS Master Switch:ALTERNATE FLAPS Master Switch:OFF (guarded position) –OFF (guarded position) –Normal operating position.Normal operating position.

ARM –ARM –• Activates standby pump. Activates standby pump. • Closes trailing edge flap bypass valve Closes trailing edge flap bypass valve (to prevent (to prevent

hydraulic lock of flap drive unit)hydraulic lock of flap drive unit)..• Arms the standby hydraulic LOW PRESSURE Arms the standby hydraulic LOW PRESSURE

light. light. • Arms the ALTERNATE FLAPS position switch.Arms the ALTERNATE FLAPS position switch.• Arms the leading edge standby drive extension Arms the leading edge standby drive extension

shutoff valve.shutoff valve.




ALTERNATE FLAPS Position Switch:ALTERNATE FLAPS Position Switch:Functions only when the ALTERNATE FLAPS Functions only when the ALTERNATE FLAPS master switch is in the ARM position.master switch is in the ARM position.

UP –UP –• Electrically retracts trailing edge flaps.Electrically retracts trailing edge flaps.• Leading edge devices remain extended and Leading edge devices remain extended and

cannot be retracted by the alternate flaps system.cannot be retracted by the alternate flaps system.

OFF –OFF –Normal operating position.Normal operating position.

DOWN (spring loaded to OFF) –DOWN (spring loaded to OFF) –• (Momentary) Opens the leading edge standby (Momentary) Opens the leading edge standby

drive extension shutoff valve and fully extends drive extension shutoff valve and fully extends leading edge devices using standby hydraulic leading edge devices using standby hydraulic pressure.pressure.

• (Hold) Electrically extends trailing edge flaps (Hold) Electrically extends trailing edge flaps (no asymmetry protection is provided).(no asymmetry protection is provided).


Hydraulic IndicatorsHydraulic Indicators

““A” and “B” Hydraulic A” and “B” Hydraulic System Pressure GaugeSystem Pressure Gauge

““A” Hydraulic System A” Hydraulic System Quantity GaugeQuantity Gauge

““B” Hydraulic System B” Hydraulic System Quantity GaugeQuantity Gauge



““A” and “B” Hydraulic System Pressure GaugeA” and “B” Hydraulic System Pressure Gauge• Indicates total system pressure for the “A” and Indicates total system pressure for the “A” and

“B” hydraulic system.“B” hydraulic system. Normal pressure (green): 3000 psi.Normal pressure (green): 3000 psi. Maximum pressure (red): 3500 psi.Maximum pressure (red): 3500 psi.

• Two needles, “A” and “B”.Two needles, “A” and “B”.

Note: When both pumps for a system are OFF, Note: When both pumps for a system are OFF, respective pointer reads zero.respective pointer reads zero.



““A” Hydraulic System Quantity GaugeA” Hydraulic System Quantity Gauge• Indicates quantity of hydraulic fluid in the Indicates quantity of hydraulic fluid in the

“A” system reservoir.“A” system reservoir.• If needle points to “RFL” (refill), reservoir needs If needle points to “RFL” (refill), reservoir needs

more fluid.more fluid.• Small blue dot is a calibration point used by Small blue dot is a calibration point used by

maintenance.maintenance.• FULL (F) = 4.8 U.S. gallonsFULL (F) = 4.8 U.S. gallons• REFILL (RFL) = 4.2 U.S. gallons REFILL (RFL) = 4.2 U.S. gallons • For EIS Secondary display For EIS Secondary display

FULL (F) = 100% = 4,8 USGFULL (F) = 100% = 4,8 USGREFILL (RFL) = 88% = 4,2 USGREFILL (RFL) = 88% = 4,2 USG



““B” Hydraulic System Quantity GaugeB” Hydraulic System Quantity Gauge• Indicates quantity of hydraulic fluid in the Indicates quantity of hydraulic fluid in the

“B” system reservoir.“B” system reservoir.• If needle points to “RFL” (refill), reservoir needs If needle points to “RFL” (refill), reservoir needs

more fluid.more fluid.• Small blue dot is a calibration point used by Small blue dot is a calibration point used by

maintenance. maintenance. • FULL (F) = 7.2 U.S. gallons or 100% on EISFULL (F) = 7.2 U.S. gallons or 100% on EIS• REFILL (RFL) = 6.4 U.S. gallons or 88% on EISREFILL (RFL) = 6.4 U.S. gallons or 88% on EIS

This concludes the review of the Hydraulic Panels and Indicators. The remainderThis concludes the review of the Hydraulic Panels and Indicators. The remainderof the presentation will discuss the hydraulic system in greater detail.of the presentation will discuss the hydraulic system in greater detail.

Click Click NextNext to continue. to continue.


“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

System Description

There are three hydraulics systems: “A,” “B,” and Standby. Each hydraulic system has a fluid reservoir There are three hydraulics systems: “A,” “B,” and Standby. Each hydraulic system has a fluid reservoir located in the main gear wheel well. System “A” and “B” reservoirs are pressurized by bleed air. A located in the main gear wheel well. System “A” and “B” reservoirs are pressurized by bleed air. A balance line connects the standby system reservoir to the “B” system reservoir for pressurization and balance line connects the standby system reservoir to the “B” system reservoir for pressurization and servicing. Pressurization of all reservoirs ensures positive fluid flow from the reservoirs to the pumps servicing. Pressurization of all reservoirs ensures positive fluid flow from the reservoirs to the pumps and maintains normal return pressure to the hydraulic system. and maintains normal return pressure to the hydraulic system.

See picture of See picture of ““A” system reservoirA” system reservoir

See picture of See picture of standby system standby system

reservoir and pumpreservoir and pumpSee picture of See picture of

““B” system reservoirB” system reservoir


“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

System Description

Both “A” and “B” hydraulic system have a total of two pumps each; one engine-driven pump, and one Both “A” and “B” hydraulic system have a total of two pumps each; one engine-driven pump, and one electric motor-driven pump. The “A” system engine-driven pump is operated by the No. 1 engine, and electric motor-driven pump. The “A” system engine-driven pump is operated by the No. 1 engine, and the “B” system engine-driven pump is operated by the No. 2 engine. The engine-driven pumps deliver the “B” system engine-driven pump is operated by the No. 2 engine. The engine-driven pumps deliver approximately 22 gallons/min. The ENG 1 or ENG 2 pump ON/OFF switch controls the engine-driven approximately 22 gallons/min. The ENG 1 or ENG 2 pump ON/OFF switch controls the engine-driven pump output pressure. Positioning the switch to OFF isolates fluid flow from the system components by pump output pressure. Positioning the switch to OFF isolates fluid flow from the system components by energizing a depressurization solenoid. However, the pump will continue to rotate as long as the engine energizing a depressurization solenoid. However, the pump will continue to rotate as long as the engine is operating. It is recommended that the engine hydraulic pump switches remain ON at shutdown to is operating. It is recommended that the engine hydraulic pump switches remain ON at shutdown to prolong the service life of the depressurizing solenoid.prolong the service life of the depressurizing solenoid.


“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

System Description

The ELEC 2 (“A” system) or ELEC 1 (“B” system) pump ON/OFF switch controls the respective electric The ELEC 2 (“A” system) or ELEC 1 (“B” system) pump ON/OFF switch controls the respective electric motor-driven pump. The electric motor-driven pumps deliver approximately six gallons/min. If an motor-driven pump. The electric motor-driven pumps deliver approximately six gallons/min. If an overheat condition is detected in the pump or in the case drain line, the respective OVERHEAT light overheat condition is detected in the pump or in the case drain line, the respective OVERHEAT light illuminates. Note the labeling of the electric motor-driven pumps on the panel: ELEC 2 for “A” system illuminates. Note the labeling of the electric motor-driven pumps on the panel: ELEC 2 for “A” system and ELEC 1 for “B” system. This serves as a reminder that the “A” system electric motor-driven pump and ELEC 1 for “B” system. This serves as a reminder that the “A” system electric motor-driven pump receives its electrical power from generator bus 2, and the “B” system electric motor-driven pump receives its electrical power from generator bus 2, and the “B” system electric motor-driven pump receives its power from generator bus 1. This ensures that at least one hydraulic pump will be available receives its power from generator bus 1. This ensures that at least one hydraulic pump will be available for each system (“A” and “B”) in the case of an engine failure. for each system (“A” and “B”) in the case of an engine failure.


“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

System Description

As the “A” and “B” system pumps operate, hydraulic fluid is used to cool and lubricate the pumps. After As the “A” and “B” system pumps operate, hydraulic fluid is used to cool and lubricate the pumps. After cooling and lubrication, the fluid travels through a case drain which leads to a heat exchanger. The heat cooling and lubrication, the fluid travels through a case drain which leads to a heat exchanger. The heat exchanger for the “A” system is located in the No. 1 fuel tank, and the heat exchanger for the “B” system exchanger for the “A” system is located in the No. 1 fuel tank, and the heat exchanger for the “B” system is located in the No. 2 fuel tank. The heat exchangers are composed of coils of fine aluminum tubing is located in the No. 2 fuel tank. The heat exchangers are composed of coils of fine aluminum tubing which use fuel as a coolant. A minimum of 250 gallons (1676 lbs.) of main tank fuel is required to provide which use fuel as a coolant. A minimum of 250 gallons (1676 lbs.) of main tank fuel is required to provide hydraulic fluid cooling. The hydraulic fluid returns to its respective reservoir after being cooled. The hydraulic fluid cooling. The hydraulic fluid returns to its respective reservoir after being cooled. The standby system does not have an associated heat exchanger.standby system does not have an associated heat exchanger.


“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

System Description

One standpipe is located in the “A” system reservoir, and is associated with the engine-driven pump. One standpipe is located in the “A” system reservoir, and is associated with the engine-driven pump. The purpose of a standpipe is to prevent total fluid loss in the system. The purpose of a standpipe is to prevent total fluid loss in the system.

If a fluid leak develops in the engine-driven pump or its related lines, the standpipe prevents complete If a fluid leak develops in the engine-driven pump or its related lines, the standpipe prevents complete fluid loss. Approximately 25% of the fluid will remain, therefore “¼” is indicated on the “A” system fluid loss. Approximately 25% of the fluid will remain, therefore “¼” is indicated on the “A” system quantity gauge. System “A” hydraulic pressure is now maintained by the electric motor-driven pump. quantity gauge. System “A” hydraulic pressure is now maintained by the electric motor-driven pump. Consequently, the system components will operate at a slower rate due to the lower volume output of Consequently, the system components will operate at a slower rate due to the lower volume output of this pump (six gallons/min.).this pump (six gallons/min.).

If a fluid leak develops in the electric motor-driven pump or its related lines, or components common to If a fluid leak develops in the electric motor-driven pump or its related lines, or components common to both the engine and electric motor-driven pumps, the quantity in the reservoir will steadily decrease to both the engine and electric motor-driven pumps, the quantity in the reservoir will steadily decrease to zero and all “A” system pressure will be lost.zero and all “A” system pressure will be lost.


Two standpipes are located in the “B” system reservoir; one standpipe for each pump. Two standpipes are located in the “B” system reservoir; one standpipe for each pump.

If a fluid leak develops in the engine-driven pump or its related lines, the standpipe prevents complete If a fluid leak develops in the engine-driven pump or its related lines, the standpipe prevents complete fluid loss. Approximately 50% of the fluid will remain, therefore “½” is indicated on the “B” system fluid loss. Approximately 50% of the fluid will remain, therefore “½” is indicated on the “B” system quantity gauge. System “B” hydraulic pressure is now maintained by the electric motor-driven pump. quantity gauge. System “B” hydraulic pressure is now maintained by the electric motor-driven pump. Consequently, the system components will operate at a slower rate due to the lower volume output of Consequently, the system components will operate at a slower rate due to the lower volume output of this pump (six gallons/min.).this pump (six gallons/min.).

If a fluid leak develops in the electric motor-driven pump or its related lines, or components common to If a fluid leak develops in the electric motor-driven pump or its related lines, or components common to both the engine and electric motor-driven pumps, the quantity in the reservoir will steadily decrease to both the engine and electric motor-driven pumps, the quantity in the reservoir will steadily decrease to zero and all “B” system pressure will be lost. However, approximately one gallon remains in the zero and all “B” system pressure will be lost. However, approximately one gallon remains in the reservoir for Power Transfer Unit operation reservoir for Power Transfer Unit operation onlyonly. Please see the Flight Control presentation for a detailed . Please see the Flight Control presentation for a detailed description of the Power Transfer Unit.description of the Power Transfer Unit.

“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

PTU control valveAutoslat operation


“A” Motor

“B” Pump


System Description


The standby hydraulic system is provided as a backup to the “A” and/or “B” hydraulic system. It is The standby hydraulic system is provided as a backup to the “A” and/or “B” hydraulic system. It is available when pressure is lost from the “A” and/or “B” hydraulic system. The standby system provides available when pressure is lost from the “A” and/or “B” hydraulic system. The standby system provides hydraulic power to only three system components: thrust reversers, leading edge devices, and standby hydraulic power to only three system components: thrust reversers, leading edge devices, and standby rudder. It should be noted that the standby system can only rudder. It should be noted that the standby system can only extendextend the leading edge devices, and has no the leading edge devices, and has no ability to ability to retractretract the leading edge devices. Please see the Flight Control presentation for a detailed the leading edge devices. Please see the Flight Control presentation for a detailed description of operation of the leading edge devices.description of operation of the leading edge devices.

The standby system has one electric motor-driven pump. The pump normally receives power from The standby system has one electric motor-driven pump. The pump normally receives power from generator bus 1. If generator bus 1 becomes inoperative, the pump will automatically receive power from generator bus 1. If generator bus 1 becomes inoperative, the pump will automatically receive power from generator bus 2. The standby pump delivers approximately three gallons/min. generator bus 2. The standby pump delivers approximately three gallons/min.

“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

Standby rudder


To return



System Description


Under normal conditions, the standby hydraulic pump is not operating. If hydraulic pressure is lost from Under normal conditions, the standby hydraulic pump is not operating. If hydraulic pressure is lost from “A” and/or “B” system, the pump may be activated manually. Under certain conditions, the standby “A” and/or “B” system, the pump may be activated manually. Under certain conditions, the standby pump will activate automatically.pump will activate automatically.

“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

Standby rudder


To return



Aileron

Rudder


System Description


The three ways to manually activate the standby hydraulic pump are:The three ways to manually activate the standby hydraulic pump are:

1) 1) Position the “A” FLT CONTROL switch to STBY RUDPosition the “A” FLT CONTROL switch to STBY RUD

2) 2) Position the “B” FLT CONTROL switch to STBY RUDPosition the “B” FLT CONTROL switch to STBY RUD

3) 3) Position the ALTERNATE FLAPS Master Switch to ARMPosition the ALTERNATE FLAPS Master Switch to ARM

“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

Standby rudder


To return



Aileron

Rudder


System Description


Automatic activation of the standby hydraulic pump occurs when all of the following conditions exist Automatic activation of the standby hydraulic pump occurs when all of the following conditions exist simultaneously:simultaneously: 1) 1) Loss of one hydraulic system (“A” or “B”) Loss of one hydraulic system (“A” or “B”)

2) 2) Trailing edge flaps extendedTrailing edge flaps extended

3) 3) Airborne, OR wheel speed greater than 60 kts.Airborne, OR wheel speed greater than 60 kts.

“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

Standby rudder


To return



Aileron

Rudder


System Description


The standby hydraulic system reservoir does not contain a standpipe. If a fluid leak develops in the The standby hydraulic system reservoir does not contain a standpipe. If a fluid leak develops in the standby system, the quantity in the reservoir will steadily decrease to zero. The standby hydraulic standby system, the quantity in the reservoir will steadily decrease to zero. The standby hydraulic LOW QUANTITY light illuminates when the reservoir is approximately half empty (50%). When the LOW QUANTITY light illuminates when the reservoir is approximately half empty (50%). When the quantity in the reservoir is zero, standby system pressure is longer available.quantity in the reservoir is zero, standby system pressure is longer available.

A leak in the standby hydraulic system has an affect on the “B” hydraulic system reservoir. Recall that a A leak in the standby hydraulic system has an affect on the “B” hydraulic system reservoir. Recall that a balance line connects the standby system reservoir to the “B” system reservoir. With a standby system balance line connects the standby system reservoir to the “B” system reservoir. With a standby system leak, not only is the standby system fluid depleted, but so is the fluid in the balance line and some of the leak, not only is the standby system fluid depleted, but so is the fluid in the balance line and some of the fluid in the “B” system reservoir. The fluid quantity in the “B” system reservoir decreases and stabilizes fluid in the “B” system reservoir. The fluid quantity in the “B” system reservoir decreases and stabilizes somewhere between “½” and “RFL” on the “B” hydraulic system quantity gauge. somewhere between “½” and “RFL” on the “B” hydraulic system quantity gauge.

“B” system

reservoir“A”

system reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Motor

Electric pump

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump


PTU use only.

Return

Standby system

reservoir

Motor50%

Standby rudder


To return



System Description


““A” Hydraulic System ComponentsA” Hydraulic System Components(With Backup System Indicated)(With Backup System Indicated)

ComponentComponent Backup System for Backup System for ComponentComponent

AileronsAilerons ““B” HydraulicsB” Hydraulics

RudderRudder ““B” HydraulicsB” Hydraulics

Elevator/Elevator FeelElevator/Elevator Feel ““B” HydraulicsB” Hydraulics

Alternate BrakesAlternate Brakes Accumulator braking via “B” Accumulator braking via “B” HydraulicsHydraulics

Landing GearLanding Gear

Landing Gear Transfer Unit. Landing Gear Transfer Unit. Retracts the landing gear using Retracts the landing gear using

“B” Hydraulics when the No. 1 “B” Hydraulics when the No. 1 engine fails during takeoff.engine fails during takeoff.

No. 1 Thrust ReverserNo. 1 Thrust Reverser Standby HydraulicsStandby Hydraulics

Power Transfer Unit (PTU)Power Transfer Unit (PTU)The PTU The PTU isis the backup for normal the backup for normal

operation of the Autoslat system via operation of the Autoslat system via “B” Hydraulics “B” Hydraulics

““A” Channel AutopilotA” Channel Autopilot No backupNo backup

Ground SpoilersGround Spoilers No backupNo backup

Inboard Flight SpoilersInboard Flight Spoilers No backupNo backup

Nose Wheel SteeringNose Wheel Steering No backupNo backup


““B” Hydraulic System ComponentsB” Hydraulic System Components(With Backup System Indicated)(With Backup System Indicated)

ComponentComponent Backup System for Backup System for ComponentComponent

AileronsAilerons ““A” HydraulicsA” Hydraulics

RudderRudder ““A” HydraulicsA” Hydraulics

Elevator/Elevator FeelElevator/Elevator Feel ““A” HydraulicsA” Hydraulics

Normal BrakesNormal Brakes Alternate Brakes via “A” HydraulicsAlternate Brakes via “A” Hydraulics

Landing Gear Transfer UnitLanding Gear Transfer UnitThe Landing Gear Transfer Unit The Landing Gear Transfer Unit isis the the

backup for normal operation of the backup for normal operation of the landing gear via “A” Hydraulics landing gear via “A” Hydraulics

Alternate Nose Wheel SteeringAlternate Nose Wheel Steering(if installed)(if installed)

The Alternate Nose Wheel Steering The Alternate Nose Wheel Steering system system isis the backup for normal the backup for normal

operation of the nose wheel via operation of the nose wheel via “A” Hydraulics“A” Hydraulics

No. 2 Thrust ReverserNo. 2 Thrust Reverser Standby HydraulicsStandby Hydraulics

Leading Edge DevicesLeading Edge Devices Standby HydraulicsStandby Hydraulics

AutoslatsAutoslats Power Transfer Unit (PTU)Power Transfer Unit (PTU)

Trailing Edge FlapsTrailing Edge Flaps Electric Motor (via flap drive unit)Electric Motor (via flap drive unit)

““B” Channel AutopilotB” Channel Autopilot No backupNo backup

AutobrakesAutobrakes No backupNo backup

Outboard Flight SpoilersOutboard Flight Spoilers No backupNo backup

Yaw DamperYaw Damper No backupNo backup


Standby Hydraulic SystemStandby Hydraulic SystemComponentsComponents

ComponentComponent

Thrust ReversersThrust Reversers

Leading Edge DevicesLeading Edge Devices(Extension Only)(Extension Only)

Standby RudderStandby Rudder


Hydraulic Components with no Backup(“A” Hydraulic System)



Supply


Case drain return

“A” system

reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Electric pump

To return

Alternate brakes



Trailing edge flaps


Autopilot B & yaw damper

If installed

“B” system


Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Motor

Electric pump

P To return



“A” Motor

“B” Pump



PTU use only.

Return

Standby system

reservoir

To return

PTU control valve

50%

Normal brakes


With a loss of “A” system hydraulics, the following items do not have a backup and therefore are no longer available:• “A” Autopilot• Ground spoilers• Inboard flight

spoilers• Nose wheel steering (if an alternate nose wheel steering

switch is not installed)

Ground spoilers


Autopilot A


Motor

Aileron

Rudder



P


Landing gearNose wheel steering

Motor



Standby rudder


Hydraulic Components with no Backup(“B” Hydraulic System)



Supply


Case drain return

“A” system

reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Electric pump

To return



If installed

“B” system


Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Electric pump

To return


“A” Motor

“B” Pump



PTU use only.

Return

Standby system

reservoir

To return

PTU control valve

50%

Ground spoilers


Autopilot A


Motor

P

Nose wheel steering

With a loss of “B” system hydraulics, the following items do not have a backup and therefore are no longer available:• “B” Autopilot • Autobrakes• Outboard flight

spoilers• Yaw Damper

Motor

PAutoslat operation




Aileron

Rudder



Trailing edge flaps

Landing gear



Normal brakes

Alternate brakes

Motor



Standby rudder


Hydraulic Components Remaining with Loss of Both “A” and “B” Hydraulic System



Supply


Case drain return

“A” system

reservoir

Pneumatic air

Return

Engine driven pump


Hydraulic shutoff

No. 1fuel tank


Electric pump

To return

Alternate brakes



If installed

“B” system


Return

Engine driven pump


Hydraulic shutoff

No. 2fuel tank


Electric pump

To return


“A” Motor

“B” Pump



PTU use only.

Return

Standby system

reservoir

To return

PTU control valve

50%

With a loss of both “A” and “B” system hydraulics, the standby system is available for the… • Thrust reversers• Leading edge

devices (extension only)• Standby rudder

The ailerons and elevator can still be operated manually (manual reversion) andbraking would be from the accumulator. Trailing edge flaps can be extended electrically, and the landing gear extended manually.

Ground spoilers


Autopilot A


Motor

P

Motor


P




Trailing edge flaps

Aileron

Rudder



Normal brakes

Nose wheel steering Landing gear


Motor



Standby rudder

b737-300/400 hydraulics

Engineering