29-11-00
ALL ú ú 02 Page 226 ú Oct 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
TASK 29-11-00-292-571
8. Bleed the Hydraulic System
__________________________
A. General
(1)
When a hydraulic component or tubing is removed and replaced, care should be taken to minimize the loss of hydrauylic fluid and subsequent entry of air into the hydraulic system. When maintenance activities result in significant air entering a hydraulic system, the system must be bled to ensure the air does not cause non-normal system behavior. Some components have specific bleeding requirements that are included in their installation procedures. The operator should be aware of the existence of specific procedures in those areas affected by the maintenance activity performed. Boeing recommends that operators perform the specific bleeding procedures for a component if activities allow air into the pressure lines immediately upstream of that component. When large portions of the system are affeted, the following general procedure may be used to bleed the flight control portions of the hydraulic system. If the landing gear system has significant air trapped in its tubing, then the affected gear will need to be cycled to fully bleed the system. These procedures are contained in AMM 32-32-00/501 (Wing Gear), 32-33-00/501 (Body Gear), and 32-34-00/501 (Nose Gear).
B.
Standard Tools and Equipment
(1)
Hydraulic Service Cart - This cart must supply a flow of BMS 3-11 fire-resistant hydraulic fluid at 30-40 gpm at 3000 psig.
C.
References
(1)
AMM 12-12-01/301, Hydraulic Systems
(2)
AMM 24-22-00/201, Manual Control
(3)
AMM 29-11-18/201, Case Drain Module
(4)
AMM 29-11-23/201, Pressure Module
(5)
AMM 32-00-30/201, Landing Gear Door Locks
(6)
AMM 54-62-00/201, Nacelle Strut Access Panels
(7)
AMM 78-31-00/201, Thrust Reverser System
D.
Access
(1)
Location Zone
454 System 1 - Strut Aft Fairing
464 System 2 - Strut Aft Fairing
735 System 2 - Wing Landing Gear Wheel Well
474 System 3 - Strut Aft Fairing
745 System 3 - Wing Landing Gear Wheel Well
484 System 4 - Strut Aft Fairing
(2)
Access Panel
454AL Trailing Edge Fairing Doors - System 1
464AL Trailing Edge Fairing Doors - System 2
474AL Trailing Edge Fairing Doors - System 3
484AL Trailing Edge Fairing Doors - System 4
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
29-11-00
ALL ú ú 01 Page 227 ú Jun 18/01
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
E. Procedure
S 862-560
(1)
Supply electrical power (AMM 24-22-00/201).
S 862-561
(2)
Release the pressure in the hydraulic system (Ref par. 5).
S 012-562
(3)
Open the fairing doors on the trailing edge of the strut
(AMM 54-62-00/201).
S 012-563
(4)
Open the right thrust reverser half (AMM 78-31-00/201).
S 982-564
WARNING: MAKE SURE ALL PERSONS AND EQUIPMENT ARE AWAY FROM THE DOOR
_______ OPERATION AREA. A FAST MOVEMENT OF THE DOORS CAN CAUSE INJURY TO PERSONS AND DAMAGE TO EQUIPMENT.
(5) Move the ground release handle for the doors of the main landing gear to the DOORS OPEN position.
S 492-568
WARNING: YOU MUST CAREFULLY DO THE STEPS IN THE TASK BELOW TO INSTALL
_______ THE LOCKS ON THE LANDING GEAR DOORS. THE DOORS CAN CLOSE QUICKLY IF YOU DO NOT INSTALL THE DOOR LOCKS CORRECTLY. THIS CAN CAUSE INJURY TO PERSONS OR DAMAGE TO EQUIPMENT.
(6)
Do this task for the wing and the body gear doors: "Landing Gear Door Lock Installation" (AMM 32-00-30/201).
S 492-569
(7)
Make sure the ground lockpins for the landing gear are installed (AMM 09-11-00/201).
S 872-570
(8)
Bleed the hydraulic system:
(a)
Disconnect the pressure hose from the Engine Driven Pump (EDP).
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