787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Hydraulics -
System Description
Copyright © The Boeing Company. See title page for details.
13.20.2 D615Z003-TBC
The pumps are controlled by the ELEC DEMAND L and R pump selectors. In the
ON position, the demand pump runs continuously. In the AUTO position, the L
and R demand pumps operate under the following conditions:
• system low pressure
• on the ground for the first three minutes after the second engine is started
• from takeoff thrust set to flaps retracted
• during descent from flaps extended until speedbrakes are stowed (left
pump only)
• thrust reverser operation
Center Hydraulic System
The center hydraulic system powers:
The ram air turbine (RAT) only provides hydraulic power to the center hydraulic
system primary flight controls.
Center Hydraulic System Electric Pumps
Two electric motor-driven pumps (EMPs) provide hydraulic power sources for the
center hydraulic system. The C1 and C2 ELEC pump selectors control pump
operation. The two center pumps alternate as a primary pump and demand pump.
The primary pump operates continuously. The center demand pump operates
under the following conditions:
• system low pressure
• from takeoff thrust set to flaps retracted
• flaps and slats not up
• gear not up
Center Hydraulic System Non–Normal Operation
The center hydraulic system has isolation functionality in the event of a leak. The
isolation function uses a Nose Gear Isolation Valve (NGIV), Reserve Steering
Isolation Valve (RSIV), Alternate Extend Isolation Valve (AEIV) and a reservoir
standpipe. The hydraulic isolation systems ensure the flight crew can lower the
landing gear and that nose wheel steering is operational for landing, roll-out and
taxi. The isolation valves operate automatically and cannot be controlled by the
crew.
• flight controls
• landing gear actuation
• leading edge slats
• nose gear steering
• right and left wing spoilers
• trailing edge flaps
February 15, 2010
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