C.
Procedure
(1)
Supply electrical power (AMM 24-22-00/201).
(2)
Release the pressure in the pneumatic system (AMM 36-00-00/201).
S 862-049
S 862-050
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
29-11-00
ALL ú ú 16 Page 218 ú Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
S 012-051
(3)
Remove the locking screws which attach the access door for the hydraulic depressurization valve to the fairing door on the trailing edge of the strut.
(a)
Remove the access door.
S 862-052
(4)
Operate the bleed valve on the reservoir pressurization module to release the pressure in the reservoir.
S 862-053
(5)
Open these circuit breakers for the applicable system:
(a)
P7 Circuit Breaker Panel
1) 7F1 HYDRAULICS DEMAND 4
2) 7G1 HYDRAULICS DEMAND 3
3) 7H1 HYDRAULICS DEMAND 2
4) 7J1 HYDRAULICS DEMAND 1
(b)
P714 Left Auxiliary External Power Center Panel
1) HYDR AUX AC PUMP 4
2) HYDR AUX AC PUMP 1
S 862-054
(6)
Make sure these circuit breakers for the applicable system are closed:
(a)
P7 Circuit Breaker Panel
1) 7F2 HYDRAULICS EDP DEPRESS 4
2) 7F3 HYDRAULICS HYDIM 1
3) 7G2 HYDRAULICS EDP DEPRESS 3
4) 7G3 HYDRAULICS HYDIM 2
5) 7H2 HYDRAULICS EDP DEPRESS 2
6) 7H3 HYDRAULICS HYDIM 3
7) 7J2 HYDRAULICS EDP DEPRESS 1
8) 7J3 HYDRAULICS HYDIM 4
(b)
P415 Main Power Distribution Panel
1) 415K37 HYD PRESS IND SYS 1
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
29-11-00
ALL ú ú 20 Page 219 ú Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
2) 415K38 HYD PRESS IND SYS 2 3) 415K39 HYD PRESS IND SYS 3
(c) P414 Main Power Distribution Panel 1) 414G23 HYD 4 PRESS IND
S 862-055
(7) Push the HYD switch on the EICAS display select panel.
S 862-056
(8) Turn off all the hydraulic pressure sources in the system: (a) Put the applicable HYD PUMPS ENGINE switch on the P5 panel in the OFF position. (b) Put the applicable HYD PUMPS DEMAND switch on the P5 panel in the OFF position. (c) Attach a DO-NOT-OPERATE tag to the hydraulic control module. (d) Turn off the ground hydraulic power source if it is applicable.
S 862-057
WARNING: MAKE SURE THE RUDDER CAN MOVE FREELY BEFORE YOU OPERATE THE
_______ RUDDER PEDALS. AN ACCIDENTAL MOVEMENT OF THE RUDDER CAN CAUSE INJURY TO PERSONS AND DAMAGE TO EQUIPMENT.
(9)
Monitor the system pressure on the EICAS display and operate the rudder to release the system pressure.
S 862-058
(10)
Monitor the HYD BRAKE PRESS gage on the captain's instrument panel and operate the brake pedals to release the brake source pressure.
S 862-059
(11)
If the hydraulic pressure is supplied with a cart, isolate the hydraulic system:
(a)
Put the L ISLN and R ISLN switches on the P5 panel in the closed position.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
29-11-00
ALL ú ú 15 Page 220 ú Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
(b) Put the four ENGINE BLEED switches on the P5 panel in the OFF position.
S 412-521
(12)
Install the access door for the hydraulic depressurization valve to the fairing door on the trailing edge of the strut with the locking screws.
