Boeing 767 300 Hydraulics

B767

Hydraulics DO NOT USE FOR FLIGHT

Boeing B767 - Systems Summary [Hydraulics]

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.

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Hydraulic Systems Schematic SYS PRESS

SYS PRESS

SYS PRESS

QTY

QTY

QTY

P R I M A R Y

RESERVE BKS & STRG ON

L ENG

R ENG

C 1-ELEC-2

ON

ON

ON

ON

PRESS

PRESS

PRESS

PRESS

OVHT

OVHT

OVHT

OVHT

AIR

ELEC

PRESS

PRESS

ELEC

PRESS D E OVHT M AUTO A ON N OFF D

VALVE

PUMPS

HYD

OVHT OFF

AUTO

P R I M A R Y

RAM AIR TURB PRESS UNLKD

D E M AUTO A ON N OFF D OVHT

ON

FLT CTRL

PRIMARY FLOW DEMAND FLOW FLT CTRL L REV

TAILSKID

PES

HYD DRIVEN GENERATOR

NORM BRKS FLT CTRL

SLATS

ALTN BRAKES

R REV

FLAPS

NOSE WHEEL STEERING

LND GEAR ISLN

ISLN L ENG

L ELEC

DISCH 1

L E F T

2

R ENG

ELEC C2

ELEC C1

AIR C

RAT

R ELEC

SOV

SOV ISLN

LEFT RESERVOIR PUMP ISLN

CENTER RESERVOIR ISOLATION VALVE

SOV

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RIGHT RESERVOIR SHUTOFF VALVE

CHECK VALVE


SYS PRESS

SYS PRESS

SYS PRESS

QTY

QTY

QTY

P R I M A R Y

RESERVE BKS & STRG ON

L ENG

R ENG

C 1-ELEC-2

ON

ON

ON

ON

PRESS

PRESS

PRESS

PRESS

OVHT

OVHT

OVHT

OVHT

AIR

ELEC

PRESS

PRESS

ELEC

PRESS D E OVHT M AUTO A ON N OFF D

VALVE

PUMPS

HYD

OVHT OFF

AUTO

P R I M A R Y

RAM AIR TURB PRESS UNLKD

D E M AUTO A ON N OFF D OVHT

ON

FLT CTRL

PRIMARY FLOW DEMAND FLOW FLT CTRL

TAILSKID

PES

HYD DRIVEN GENERATOR

NORM BRKS FLT CTRL

SLATS

ALTN BRAKES

FLAPS

NOSE WHEEL STEERING

LND GEAR ISLN

ISLN L ENG

L ELEC

DISCH 1

L E F T

2

R ENG

ELEC C2

ELEC C1

AIR C

RAT

R ELEC

SOV

SOV ISLN

LEFT RESERVOIR PUMP ISLN

CENTER RESERVOIR ISOLATION VALVE

SOV

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RIGHT RESERVOIR SHUTOFF VALVE

CHECK VALVE


Left Hydraulic System The left hydraulic system powers: • flight controls • left engine thrust reverser The system consists of a reservoir, engine–driven primary pump, and an electric motor–driven demand pump.

Fluid Supply Hydraulic 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 engine–driven 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.

Engine–driven Primary Pump The primary hydraulic system pump is an engine–driven 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 Motor–driven Demand Pump An electric motor–driven 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 engine–driven 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 Indications The SYS PRESS light illuminates and the EICAS caution message L HYD SYS PRESS displays when the hydraulic system pressure is low.

Right Hydraulic System The 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, engine–driven primary pump, and an electric motor–driven demand pump.

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

Engine–driven Primary Pump The right engine–driven 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 Motor–driven Demand Pump The right electric motor–driven 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 Indications The right system pressure indications are similar to the left system. The associated message for low system pressure is R HYD SYS PRESS.

Center Hydraulic System The center system powers: • flight controls • nose wheel steering • flaps and slats • alternate brakes • landing gear • hydraulic driven generator • tailskid Page 5


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

Fluid Supply The 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 Motor–driven Primary Pumps The two center electric motor–driven 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.

Air–driven Demand Pump An air–driven 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 motor–driven 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 Indications The 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 Isolation The 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 Generator A 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) Pump When 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 C DEM HYD OVHT

Level

Light

Aural

Condition

Advisory

OVHT

Pump temperature is high.

Advisory

PRESS

Pump output pressure is low.

Advisory

QTY

Hydraulic quantity is low.

Caution

SYS PRESS

Advisory

UNLKD

L DEM HYD OVHT R DEM HYD OVHT C HYD 1 OVHT C HYD 2 OVHT L PRIM HYD OVHT R PRIM HYD OVHT 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 C HYD QTY L HYD QTY R HYD QTY C HYD SYS PRESS L HYD SYS PRESS

Beeper

Hydraulic system pressure is low.

R HYD SYS PRESS RAT UNLOCKED

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The ram air turbine is not stowed and locked.


Hydraulic Panel 1

SYS PRESS

SYS PRESS

SYS PRESS

2

QTY

QTY

QTY

3 4 5 6

7

P R I M A R Y

L ENG

HYD PUMPS C 1 - ELEC - 2

R ENG

ON

ON

ON

ON

PRESS

PRESS

PRESS

PRESS

OVHT

OVHT

OVHT

OVHT

ELEC

AIR

PRESS

PRESS

D E OVHT M AUTO A ON OFF N D

ELEC

OVHT OFF

AUTO

P R I M A R Y

PRESS

D E M AUTO A OFF ON N D

OVHT

ON

OVERHEAD PANEL 1

System Pressure (SYS PRESS) Lights

Illuminated (amber) – system pressure is low. 2

Reservoir Low Quantity (QTY) Lights

Illuminated (amber) – reservoir quantity is low. 3

Left/Right Engine (L/R ENG) Primary Pump Switches

ON – the engine–driven hydraulic pump pressurizes when engine rotates. Off (ON not visible) – the engine–driven hydraulic pump is turned off and depressurized. 4

Pump Pressure (PRESS) Lights

Illuminated (amber) – pump output pressure is low. 5

Pump Overheat (OVHT) Lights

Illuminated (amber) – pump temperature is high. Page 9

Boeing B767 - Systems Summary [Hydraulics] 6

Center 1/2 Electric (C1/2 ELEC) Primary Pump Switches

ON – the electric motor–driven pump pressurizes the center hydraulic system. OFF (ON not visible) – the electric motor–driven 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

HYD QTY

L

C

R

.75 RF

1.00

1.00

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

Miscellaneous Hydraulic System Controls Reserve Brakes and Steering Reset/Disable Switch RESERVE BRAKES & STRG RESET/ C HYD SYS DISABLE

1

ISLN

NORM

2

ACCESSORY PANEL 1

Reset/Disable Switch

RESET/DISABLE – resets or disables the automatic isolation feature of the center hydraulic system. NORM – the isolation feature is armed for automatic operation. Page 10


2

Isolation (ISLN) Light

Illuminated (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 RAM AIR TURB 1 2

PRESS

3

UNLKD

OVERHEAD PANEL 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.

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Boeing 767 300 Hydraulics

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