S 864-003

 (2)
Release the pressure in the pneumatic system (Ref 36-00-00/201).

 S 864-004

 (3)  
Push the ECS switch on the EICAS display select panel to show the EICAS ECS synoptic page.

 S 864-035

 (4)
Make sure that the DUCT PSI left and right are approximately zero.

 S 864-005

 (5)  
Open these circuit breakers and attach DO-NOT-CLOSE tags:

 (a)  
P6 Main Power Distribution Panel 1) 6E35, A/C CONT CARGO - AFT LWR (Aft cargo valve) 2) 6E36, A/C CONT CARGO - FWD LWR (Forward cargo valve)

 (b)  
P414 Power Distribution Center-Left 1) 414A10, LWR CARGO A/C VLV - FWD (Forward cargo valve) 2) 414A11, LWR CARGO A/C VLV - AFT (Aft cargo valve)

 S 024-032
 (6) Do these steps to remove the aft cargo trim air shutoff valve:
 (a)  Make sure the landing gear ground locks are installed (Ref 09-11-00/201).
 WARNING: REFER TO THE SPECIFIED PROCEDURE TO INSTALL THE DOOR LOCKS
_______ CORRECTLY. THE DOORS CAN CLOSE QUICKLY IF YOU DO NOT INSTALL THE DOOR LOCKS CORRECTLY. THIS CAN CAUSE INJURIES TO PERSONS AND DAMAGE TO EQUIPMENT.
 (b)  Install the body and the wing gear door locks (Ref 32-00-30/201).
 S 014-034
 (7)  Do this step to remove the forward cargo shutoff valve:
 (a)  Open the access door 192NR on the air conditioning equipment bay (Ref 06-09-03/201).
 S 014-033
 (8)  Remove the electrical connector from the valve:
 (a)  
Forward Cargo Shutoff Valve, DV491

 (b)  
Aft Cargo Shutoff Valve, DV494

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747-400 MAINTENANCE MANUAL
 S 034-011
 (9) Remove the bonding jumper from the valve.
 S 034-012
 WARNING: MAKE SURE THERE IS NO PRESSURE IN THE PNEUMATIC SYSTEM BEFORE
_______ YOU DO THE NEXT STEP. INJURY TO PERSONS CAN OCCUR IF YOU TRY TO REMOVE THE VALVE WITH PRESSURE IN THE PNEUMATIC SYSTEM.
 (10)
 Remove the clamps from each end of the valve.

 S 024-013

 (11)
 Remove the valve from the duct.

 S 034-014

 (12)
 Put covers on the duct openings.

 TASK 21-28-04-404-015
 3. Valve Installation
__________________
 A. References
 (1)
09-11-00/201, Towing

 (2)
21-00-00/201, Air Conditioning

 (3)
24-22-00/201, Manual Control

 (4)
32-00-30/201, Landing Gear Door Locks

 (5)
36-00-00/201, Pneumatic System

 (6)
IPC 21-61-08 Fig. 01

 (7)
IPC 21-44-54 Fig.01

 (8)
WDM 21-28-42

 (9)
WDM 21-28-52

 (10)
 SSM 21-28-04

 (11)
 SSM 21-28-05

 B. Access
 (1)  Location Zone
 134 Air Conditioning Equipment Bay, RH
 138 Body Landing Gear Well, RH

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A
747-400 MAINTENANCE MANUAL
 (2)  Access Panel
 192NR Air Conditioning Access Door

 C. Procedure
 S 434-016
 (1)  
Remove the covers from the duct openings.

 S 214-017

 (2)  
Make sure the duct and the valve flanges are clean.

 S 434-035

 (3)
Put the valve and the seals in the duct and install the clamps.

 NOTE: Install the forward cargo valve with the flow arrow pointed
____ forward and the aft cargo valve with the arrow pointed up.
 S 434-020
 (4)  
Tighten the clamp nuts to 45-55 pound-inches.

 S 434-021

 (5)  
Connect the bonding jumper to the valve.
　
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