boeing 767 300 hydraulics

B767

Hydraulics

DONOTUSEFORFLIGHT

Introduction The airplane has three independent hydraulic systems: left, right, and center. The hydraulic systems power the:

flight controls leading edge slats trailing edge flaps landing gear wheel brakes nose wheel steering autopilot servos thrust reversers tailskid

Flight control system components are distributed so that any one hydraulic system can provide adequate airplane controllability.Hydraulic fluid is supplied to each hydraulic pump from the associated system reservoir. The reservoirs are pressurized by the bleed air system.

Boeing B767 - Systems Summary [Hydraulics]

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Hydraulic Systems Schematic

QTYPRESS SYS

QTYPRESS SYS

OVHT

PRESS

OVHT

PRESS

LEFT

DISCH21

L REV

FLT CTRL

R REV

NORM BRKS

ENG

SOVSOV

ENGELEC

RAT

ISLNSOV

LC2

R

SLATS

HYD DRIVENGENERATOR

NOSE WHEELSTEERING LND GEAR

FLT CTRL

ISLN

PES

ELECC1

ISLN

FLT CTRL

ALTN BRAKESFLAPS

TAILSKID

PRIMARY FLOWDEMAND FLOW

ELECRAIR

CELECL

ISLN

PUMPISOLATIONVALVE

SHUTOFF CHECKVALVE

LEFTRESERVOIR

CENTERRESERVOIR

RIGHTRESERVOIR

VALVE

PUMPS

DNAMED

C

YRAMIRPENG

R

ELEC

ONOFFAUTOONOFF

AUTO

OVHT

PRESSON

OVHT

PRESSON

OVHT

PRESSON

OVHT

QTYPRESS SYS

YRAMIRP ENG

LHYD

1-ELEC-2

PRESSON

AIR

DNAMED

ELEC

ONOFFAUTO

OVHT

PRESS

RESERVEBKS & STRG

ON

VALVE

PRESS

UNLKD

RAM AIR TURB


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LEFT

DISCH21

FLT CTRL

NORM BRKS

ENG

SOVSOV

ENGELEC

RAT

ISLNSOV

LC2

R

SLATS

HYD DRIVENGENERATOR

NOSE WHEELSTEERING LND GEAR

FLT CTRL

ISLN

PES

ELECC1

ISLN

FLT CTRL

ALTN BRAKESFLAPS

TAILSKID

PRIMARY FLOWDEMAND FLOW

ELECRAIR

CELECL

ISLN

PUMPISOLATIONVALVE

SHUTOFF CHECKVALVE

LEFTRESERVOIR

CENTERRESERVOIR

RIGHTRESERVOIR

VALVE

QTYPRESS SYS

QTYPRESS SYS

OVHT

PRESS

OVHT

PRESS

PUMPS

DNAMED

C

YRAMIRPENG

R

ELEC

ONOFFAUTOONOFF

AUTO

OVHT

PRESSON

OVHT

PRESSON

OVHT

PRESSON

OVHT

QTYPRESS SYS

YRAMIRP ENG

LHYD

1-ELEC-2

PRESSON

AIR

DNAMED

ELEC

ONOFFAUTO

OVHT

PRESS

RESERVEBKS & STRG

ON

VALVE

PRESS

UNLKD

RAM AIR TURB


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Left Hydraulic System The left hydraulic system powers:

flight controls left engine thrust reverser

The system consists of a reservoir, enginedriven primary pump, and an electric motordriven demand pump.

Fluid SupplyHydraulic fluid is supplied to each hydraulic pump from a reservoir. The reservoir is pressurized by the bleed air system. A quantity measuring system provides information to the EICAS status display. RF displays on the EICAS status page when a reservoir requires refilling prior to dispatch. The QTY light illuminates and the EICAS advisory message L HYD QTY displays when the reservoir quantity is low.Fluid for the enginedriven pump flows through a shutoff valve controlled by the engine fire switch. Pulling the fire switch shuts off the flow of fluid to the engine pump and depressurizes the pump.

Enginedriven Primary PumpThe primary hydraulic system pump is an enginedriven pump. The primary pump PRESS light illuminates and the EICAS advisory message L HYD PRIM PUMP displays when the pump output pressure is low. The pump OVHT light illuminates and the EICAS advisory message L PRIM HYD OVHT displays when the pump temperature is high.

Electric Motordriven Demand PumpAn electric motordriven demand pump provides additional hydraulic power either on demand or continuously for periods of high system demand. The demand pump also provides a backup hydraulic power source for the enginedriven primary pump.The pump PRESS light illuminates and the EICAS advisory message L HYD DEM PUMP displays when the pump output pressure is low. The pump OVHT light illuminates and the EICAS advisory message L DEM HYD OVHT displays when the pump temperature is high.To reduce electrical load, the left electric demand pump is inhibited on the ground during engine start of either engine, when only one electrical generator is operating. The left demand pump PRESS and SYS PRESS lights may illuminate when starting engines on the ground.


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System Pressure IndicationsThe SYS PRESS light illuminates and the EICAS caution message L HYD SYS PRESS displays when the hydraulic system pressure is low.

Right Hydraulic SystemThe right hydraulic system is similar to the left system. The right system powers:

flight controls normal brakes pitch enhancement system right engine thrust reverser

The system consists of a reservoir, enginedriven primary pump, and an electric motordriven demand pump.

Fluid SupplyThe right reservoir is similar to the left system. The associated EICAS message for low reservoir quantity is R HYD QTY.

Enginedriven Primary PumpThe right enginedriven primary pump is identical to the left system. The associated EICAS messages for low pump output pressure or high pump temperature are R HYD PRIM PUMP and R PRIM HYD OVHT.

Electric Motordriven Demand PumpThe right electric motordriven demand pump is identical to the left system. The associated EICAS messages for low pump output pressure or high pump temperature are R HYD DEM PUMP and R DEM HYD OVHT.

System Pressure IndicationsThe right system pressure indications are similar to the left system. The associated message for low system pressure is R HYD SYS PRESS.

Center Hydraulic SystemThe center system powers:

flight controls nose wheel steering flaps and slats alternate brakes landing gear hydraulic driven generator tailskid


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The system consists of a reservoir, two electric motordriven pumps, an airdriven demand pump, and a ram air turbine (RAT) pump.

Fluid SupplyThe center reservoir is similar to the left system. The associated EICAS messages for low reservoir quantity is C HYD QTY.The reservoir maintains reserve hydraulic fluid for use by the brakes and steering in the event of a center system hydraulic leak.

Electric Motordriven Primary PumpsThe two center electric motordriven primary pumps are identical to the left and right system electric motor-driven pumps. The C2 pump may be load shed automatically to reduce electrical loads. The associated EICAS messages for low pump output pressure or high pump temperature are C HYD PRIM 1, C HYD PRIM 2, C HYD 1 OVHT, and C HYD 2 OVHT.

Airdriven Demand PumpAn airdriven demand pump provides additional hydraulic power either on demand or continuously for periods of high system demand. The demand pump also provides a backup hydraulic power source for the electric motordriven primary pumps.The pump PRESS light illuminates and the EICAS advisory message C HYD DEM PUMP displays when the pump output pressure is low. The pump OVHT light illuminates and the EICAS advisory message C DEM HYD OVHT displays when the pump temperature is high.

System Pressure IndicationsThe center system pressure indications are similar to the left system. The associated message for low system pressure is C HYD SYS PRESS.

Reserve Brakes and Steering IsolationThe center number one electric primary hydraulic pump is automatically isolated, if system quantity is sensed low, to provide hydraulic pressure to the reserve brakes and steering system.

Hydraulic Driven GeneratorA hydraulic driven generator is automatically powered by the center hydraulic system when electrical power is lost from both main AC busses. The center air demand pump will then operate continuously to ensure sufficient hydraulic pressure to drive the generator.


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Ram Air Turbine (RAT) PumpWhen deployed, the RAT, provides hydraulic power to the flight controls portion of the center hydraulic system. The RAT provides adequate hydraulic power at speeds above 130 knots. In flight, the RAT deploys automatically when both engines fail. The RAT is inhibited from auto deployment on the ground.The RAT can be deployed manually by pushing the RAM AIR TURB switch. The UNLKD light illuminates and the EICAS advisory message RAT UNLOCKED displays when the RAT is not stowed and locked. Once the RAT is producing pressure the ram air turbine PRESS light illuminates. The SYS PRESS light remains illuminated if the RAT is the only source of center system pressure. Once deployed, the RAT cannot be stowed in flight.


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Hydraulics EICAS Messages The following EICAS messages can be displayed.

Message Level Light Aural Condition

C DEM HYD OVHT

L DEM HYD OVHT

R DEM HYD OVHT

C HYD 1 OVHT

C HYD 2 OVHT

L PRIM HYD OVHT

R PRIM HYD OVHT

Advisory OVHT Pump temperature is high.

C HYD DEM PUMP

L HYD DEM PUMP

R HYD DEM PUMP

L HYD PRIM PUMP

R HYD PRIM PUMP

C HYD PRIM 1

C HYD PRIM 2

Advisory PRESS Pump output pressure is low.

C HYD QTY

L HYD QTY

R HYD QTY

Advisory QTY Hydraulic quantity is low.

C HYD SYS PRESS

L HYD SYS PRESS

R HYD SYS PRESS

Caution SYS PRESS

Beeper Hydraulic system pressure is low.

RAT UNLOCKED Advisory UNLKD The ram air turbine is not stowed and locked.


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Hydraulic Panel

1 System Pressure (SYS PRESS) Lights Illuminated (amber) system pressure is low.

2 Reservoir Low Quantity (QTY) LightsIlluminated (amber) reservoir quantity is low.

3 Left/Right Engine (L/R ENG) Primary Pump Switches ON the enginedriven hydraulic pump pressurizes when engine rotates.Off (ON not visible) the enginedriven hydraulic pump is turned off and depressurized.

4 Pump Pressure (PRESS) Lights Illuminated (amber) pump output pressure is low.

PRESS

OVHT

PRESS

OVHT

QTY

SYSPRESS

AUTO

OVERHEAD PANEL

HYD PUMPS

ENGR

- -2ELEC1C

ENGL

OVHT

ON

PRESS

ON

PRESS

ON

PRESS

ON

PRESS

OVHTOVHTOVHT

QTYQTY

SYSPRESS

PRESS

OVHT

DNAMED

YRAMIRP

DNAMED

YRAMIRP

ON ON ONAUTO AUTOOFF OFF OFF

ELECAIRELEC

1

2

3

4

5

6

SYSPRESS

7

5 Pump Overheat (OVHT) Lights Illuminated (amber) pump temperature is high.


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6 Center 1/2 Electric (C1/2 ELEC) Primary Pump Switches ON the electric motordriven pump pressurizes the center hydraulic system.OFF (ON not visible) the electric motordriven hydraulic pump is turned off.

7 Left/Right Electric and Center Air (L/R ELEC and C AIR) Demand Pump Selectors

ON continuous operation.AUTO

left/right electric pumps operate when engine pump pressure is low center air demand pump operates when both center electric pump

pressures are low center air demand pump operates when heavy load items are selected

OFF pump off.

Status Display

1 Hydraulic Fluid Quantities (HYD QTY) displays system reservoir quantity (1.00 is the normal service level) RF (magenta) displayed when the reservoir requires refilling

Miscellaneous Hydraulic System ControlsReserve Brakes and Steering Reset/Disable Switch

EICAS STATUS DISPLAY

1.00.75RF 1.00HYD QTYC RL

1

ISLN

C HYD SYSRESERVE BRAKES & STRG

RESET/DISABLE

NORM

ACCESSORY PANEL

1

2

1 Reset/Disable SwitchRESET/DISABLE resets or disables the automatic isolation feature of the center hydraulic system.NORM the isolation feature is armed for automatic operation.


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2 Isolation (ISLN) LightIlluminated (white) the center number one electric primary hydraulic pump is isolated to provide hydraulic pressure to the reserve brakes and steering system.

Ram Air Turbine

1 RAM AIR Turbine (TURB) Switch Push deploys the RAT.

2 Ram Air Turbine Pressure (PRESS) Light Illuminated (green)

the RAT is deployed the RAT is producing hydraulic pressure

3 Ram Air Turbine Unlocked (UNLKD) Light Illuminated (amber) the RAT is not stowed and locked.

RAM AIR TURB

UNLKD

PRESS

OVERHEAD PANEL

1

2

3


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boeing 767 300 hydraulics

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