The hydraulic power on the aircraft is used to operate different aircraft systems and to move controls.

The hydraulic power system supplies power to the aircraft flight controls, landing gears, nose wheel steering, brakes, and thrust reversers from three independent hydraulic systems. These systems are identified as the left, right, and auxiliary hydraulic systems.

Temperature control for the left and right hydraulic systems is done through fuel heat exchangers. The direct current motor pumps (DCMPs) in the auxiliary hydraulic system are air cooled.

The three systems use a phosphate-ester-type hydraulic fluid pressurized at 3,000 psi (20,684 kPa). Each system uses hydraulic pressure to move aircraft hydraulic controls through different actuators.

The left hydraulic system operates the left engine thrust reverser, landing gears, nose wheel steering, inboard brakes, and the flight control components that follow:

• Inboard multifunction flight spoilers
• Inboard ground spoilers
• Upper rudder power control unit (PCU)
• Left and right inboard elevators PCUs
• Flaps (alternate)

The right hydraulic system operates the right engine thrust reverser, outboard brakes, and the flight control components that follow:

• Outboard multifunction flight spoilers
• Outboard ground spoilers
• Lower rudder PCU
• Left and right outboard elevators PCUs
• Flaps (normal)

The right hydraulic system also operates a hydraulic power transfer unit (PTU) to transmit secondary power to the main landing gear, during a low pressure condition in the left hydraulic system.

The auxiliary hydraulic system supplies auxiliary power to the rudder, to adjust for an asymmetric thrust condition if there is a loss of either the left or right engine.

The hydraulic pressure indication for the three hydraulic systems is available in the flight compartment through the engine indicating and crew alerting system (EICAS). The hydraulic pressure flow paths and main components status are also shown on the EICAS.

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