(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

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 C. Procedure
 S 494-039
 WARNING: USE THE TAIL SUPPORT EQUIPMENT IF YOU CANNOT KEEP THE CENTER OF
_______ GRAVITY IN THE LIMITS GIVEN BY THE WEIGHT AND BALANCE MANUAL. IF THE AIRPLANE CENTER OF GRAVITY IS NOT IN THESE LIMITS, THE AFT END OF THE AIRPLANE CAN HIT THE GROUND. DAMAGE TO EQUIPMENT AND INJURY TO PERSONS CAN OCCUR.
 (1)  Install the tail support equipment if you cannot keep the airplane center of gravity in the limits given in the weight and balance manual (AMM 07-11-08/201).
 S 654-040
 WARNING: YOU MUST DEFUEL THE CENTER WING TANK AND THE APPLICABLE MAIN
_______ TANK WHEN THE DISCHARGE CHECK VALVE IS REMOVED (REFER TO THE STEPS THAT FOLLOW). A FUEL SPILL CAN OCCUR WHEN FUEL FLOWS THROUGH THE JETTISON INTERCONNECT LINE FROM AN ADJACENT FUEL TANK. A FUEL SPILL CAN CAUSE INJURY TO PERSONS.
 (2)  Defuel the fuel tanks listed below for the applicable
 override/jettison pump (AMM 28-26-00/201). ~.......................................................................... |OVERRIDE/JETTISON PUMP|FUEL TANKS THAT MUST BE DEFUELED | ............................................................................ |NO. 2 MAIN TANK |NO. 2 MAIN TANK |CENTER WING TANK BELOW THE INLETS | | | |FOR THE OVERRIDE/JETTISON PUMPS | | | |(BELOW APPROXIMATELY 2000 POUNDS/ | | | |900 KILOGRAMS) | ............................................................................ |NO. 3 MAIN TANK |NO. 3 MAIN TANK |CENTER WING TANK BELOW THE INLETS | | | |FOR THE OVERRIDE/JETTISON PUMPS | | | |(BELOW APPROXIMATELY 2000 POUNDS/ | | | |900 KILOGRAMS) | ............................................................................ |LEFT CENTER WING TANK |CENTER WING TANK|NO. 2 MAIN TANK BELOW THE LEVEL OF| | | |THE INLETS FOR THE OVERRIDE/ | | | |JETTISON PUMPS IN THE NO. 2 MAIN | | | |TANK (BELOW APPROXIMATELY 6000 | | | |POUNDS/2700 KILOGRAMS) | ............................................................................ |RIGHT CENTER WING TANK|CENTER WING TANK|NO. 3 MAIN TANK BELOW THE LEVEL OF| | | |THE INLETS FOR THE OVERRIDE/ | | | |JETTISON PUMPS IN THE NO. 2 MAIN | | | |TANK (BELOW APPROXIMATELY 6000 | | | |POUNDS/2700 KILOGRAMS) | 2......................…................…..................................1
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

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 ALL  ú ú 01 Page 402 ú Feb 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 S 864-042
 (3)  Temporarily operate the override/jettison pumps for the applicable fuel tank to make sure the low pressure warning light shows.
 S 864-019
 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.
 (4)  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 014-020
 (5)  
To remove the discharge 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 discharge check valve on the left override/jettison pump, remove the access doors 131AZ, 131BZ, 131CZ, and 131DZ.

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