The hydraulic system in the 787 no-bleed architecture is similar
to the one in the traditional architecture. There are three
independent systems — left, center, and right — that
collectively support primary flight control actuators, landing
gear actuation, nose gear steering, thrust reversers, and
leading/trailing edge flaps. The primary power source for the
left and right systems are engine-driven pumps mounted on the
engine gearbox. In addition, the left and right systems are each
powered by an electric-motor-driven hydraulic pump for peak
demands and for ground operations. The key difference between
the traditional and 787 hydraulic system is the power source for
the center system. In the traditional architecture, the center
system is powered by two large air-turbine-driven hydraulic
pumps, which operate at approximately 50 gallons per minute
(gpm) at 3,000 pounds per square inch (psi) to meet peak
hydraulic demands for landing gear actuation, high lift
actuation and primary flight control during takeoff a