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demand pumps operate under the following conditions:
• system low pressure
• immediately after both engines have been started for three minutes
• flight controls
• leading edge slats
• trailing edge flaps
• landing gear
• thrust reversers.
• nose gear steering
787 Flight Crew Operations Manual
Hydraulics -
System Description
13.20.2 Boeing Proprietary
• takeoff thrust is set and stay on until flaps are retracted
• during decent from flaps extended until speed brakes are stowed (left
pump only)
• thrust reverser operation.
Center Hydraulic System
The center hydraulic system powers:
The ram air turbine (RAT) can provide hydraulic power to the center hydraulic
system primary flight control components only.
Center Hydraulic System Electric Pumps
Two electric motor-driven pumps (EMPs) provide hydraulic power sources for the
center hydraulic system. The ELEC C1 and C2 pump selectors control pump
operation.The two center pumps alternate as a primary pump and demand pump.
The FMC determines which operates as primary or demand based on the day of
the week. The primary pump operates continuously. The center demand pump will
operate under the following conditions:
• system low pressure
• takeoff thrust is set and stay on until flaps are retracted.
Center Hydraulic System Non–Normal Operation
If center hydraulic system quantity is sensed to be low and airspeed is greater than
60 knots the:
• nose gear actuation and steering are isolated
• leading edge slats are isolated and not allowed to operate in the primary
(hydraulic) mode.
The leading edge slats are reconnected to the center hydraulic system and allowed
to operate in primary mode when:
• center hydraulic fluid quantity recovers to normal for 5 seconds, and
• the system determines that both engines have been running for more than
30 seconds.
Nose gear actuation and steering are reconnected when:
• airspeed decreases below 60 knots, or
• hydraulic pressure to the center system flight controls goes low, or
• the landing gear is selected down, both engines are normal, and both
engine–driven pumps are providing pressure.
• flight controls
• leading edge slats
• trailing edge flaps
• landing gear actuation
• nose gear steering
787 Flight Crew Operations Manual
Hydraulics -
System Description
Boeing Proprietary 13.20.3
Ram Air Turbine (RAT)
The RAT, when deployed, provides hydraulic power only to the primary flight
control components connected to the center hydraulic system. The RAT provides
hydraulic and electrical power throughout the flight envelope. In flight, the RAT
deploys automatically if:
• both engines are failed and center system pressure is low, or
• all three hydraulic system pressures are low.
• loss of all electrical power generators.
• loss of all four EMPs and an engine fails on takeoff or landing.
The RAT can be deployed manually by pushing the RAM AIR TURBINE switch.
The hot battery or APU battery bus must be powered. The center hydraulic system
does not need to be powered. The RAT is deployed by a compressed spring. Once
deployed, the RAT cannot be stowed in flight.
787 Flight Crew Operations Manual
Hydraulics -
System Description
13.20.4 Boeing Proprietary
Hydraulic Systems Schematic
LEFT
DISCH
1 2
FLT
L REV
NOSE GEAR
& STEERING
FLT
R REV
MAIN
FLAPS
PRIMARY
DEMAND
PRIMARY
DEMAND
ENG
ELEC ELEC
SOV SOV
ENG
ELEC ELEC
RAT
4650 PRESS 5010 PRESS 4850
1.15
L R
L R
ISLN ISLN
C1 C2
0.72
CTRL
FLT
GEAR CTRL
0.40 LO
CTRL
OVHT
RF
LOAD
SHED
RAM AIR
TURBINE
HYDRAULIC
AUTO
L ELEC R ELEC
R ENG
FAULT
L ENG
PR
IM
A
RY
P
RI
M
AR
Y
D
EM
AN
D
D
EM
A
ND
ON
C1 ELEC C2
OFF
AUTO
OFF ON
AUTO
OFF ON
AUTO
OFF ON
ON
ISLN SOV
Pump Isolation
valve
Shutoff
valve PRELIMINARY
787 Flight Crew Operations Manual
Hydraulics Chapter 13
EICAS Messages Section 30
Boeing Proprietary 13.30.1
13.30 Hydraulics-EICAS MessagesHydraulics, Ram Air Turbine EICAS Messages
The following EICAS messages can be displayed.
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本文链接地址：
787机组操作手册Flight Crew Operations Manual 3(104)
