Bleeding an aircraft hydraulic system

TM 55-4920-442-13&P

NOTE

Refer to the applicable aircraft publication for proper fill procedures.

a. Close HP flow control valve.

b. Open HP bypass valve.

c. Set fill pump switch to on position.

d. After filling operation is complete, close HP bypass valve, set fill pump switch to off and disconnect service hose

at aircraft.

2-15. Bleeding an aircraft hydraulic system. If an aircraft system has been drained or the hydraulic fluid supply badly

depleted, the following procedure will allow the operator to renew the system.

NOTE

Two persons are required for this operation; one to operate the test stand, the other to cycle

the aircraft controls as necessary, and monitor the filling operation from the aircraft.

a. Make certain that the test stand has been prepared for operation as described in paragraph 2-7 and is properly

connected to the aircraft. Then set 4-way valve to stand reservoir position.

NOTE

Refer to the technical publication which applies to the aircraft being serviced for correct fill

procedures as they apply to the aircraft.

b. Adjust the pump volume control for minimum flow and activate the test stand.

c. Open HP flow control valve.

d. Set selector valve in the LP filter outlet position.

e. Slowly close the HP bypass valve.

f. Set the compensator control and HP relief valve for the pressure required for the particular aircraft.

g. Slowly increase the volume output of the test stand with the volume control in accordance with aircraft

requirements.

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