28-31-11
 ALL  ú ú 01 Page 408 ú Feb 10/96
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 FUEL OVERRIDE/JETTISON PUMP INLET CHECK VALVE - REMOVAL/INSTALLATION
____________________________________________________________________
 1.  General_______
 A.  This procedure contains instructions to remove and install the inlet check valve for the override/jettison pumps.
 B.  Pump Interchangeability
 (1)  
Reference Drawing 344U0052 for pump interchangeable part requirements.

 C.  
Inlet Check Valve Access

 (1)  
An inlet check valve is installed on each of the CWT and inboard main tank override/jettison pump housings (6 total).

 (2)  
Access to the inlet check valves is through the applicable fuel tank access doors and, in the center wing tank, the spanwise beam access doors.

 TASK 28-31-12-004-001
 2.  Inlet Check Valve Removal (Fig. 401)_________________________
 A.  References
 (1)  
AMM 28-11-00/201, Fuel Tanks

 (2)  
AMM 28-26-00/201, Defueling

 (3)  
AIPC 28-31-07 Fig. 1, Item 50

 B.  
Access

 (1)  
Location Zones 131 Center Section Wing Box, Left 132 Center Section Wing Box, Right 544 Inbd Main Tank (Part), Mid Spar to Rear Spar, Left 644 Inbd Main Tank (Part), Mid Spar to Rear Spar, Right

 (2)  
Access Panels
 131AZ Spanwise Beam Access Door
 131BZ Spanwise Beam Access Door
 131CZ Spanwise Beam Access Door
 131DZ Spanwise Beam Access Door
 132AZ Spanwise Beam Access Door
 132BZ Spanwise Beam Access Door

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-31-12
 ALL  ú ú 03 Page 401 ú Oct 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 C. Procedure
 S 654-002
 (1)  Defuel the applicable fuel tank (AMM 28-26-00/201).
 S 864-016
 WARNING: CAREFULLY DO ALL THE SAFETY PROCEDURES TO DEFUEL AND GO INTO
_______ THE FUEL TANKS. INJURY TO PERSONS AND DAMAGE TO EQUIPMENT CAN OCCUR IF YOU DO NOT OBEY THE SAFETY PROCEDURES.
 (2)  Purge and go into the fuel tank (AMM 28-11-00/201).
 NOTE: Refer to this table for the access door numbers.
____
 ~................................................................. | Location | Access Door | ................................................................... | No. 2 Main Tank - Fwd | 544AB | | No. 2 Main Tank - Aft | 544AB | | No. 3 Main Tank - Fwd | 644AB | | No. 3 Main Tank - Aft | 644AB | | Center Wing Tank | 131EZ | 2......................................…..........................1
 S 014-004
 (3)  
If you remove the inlet check valve for the override/jettison pump in the center wing tank, remove the spanwise beam doors (AMM 28-11-09/401).

 (a)  
For the inlet check valve on the left override/jettison pump, remove the access doors 131AZ, 131BZ, 131CZ, and 131DZ.

 (b)  
For the inlet check valve on the right override/jettison pump, remove the access doors 131AZ, 131BZ, 132AZ, and 132BZ.

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-31-12
 ALL  ú ú 03 Page 402 ú Oct 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 034-031
 (4)  
Do these steps to remove the inlet check valve:

 (a)  
Remove the lockwire from the inlet check valve screws.

 (b)  
Remove the screws and washers (3 locations) that attach the inlet check valve to the outer override/jettison pump housing.

 (c)  
Isolate the inlet check valve and packing from the override/jettison pump housing.

 (d)  
Remove the inlet check valve and packing from the fuel tank.

 (e)  
Discard the packing.

 TASK 28-31-12-404-007
　
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