C.  
To get to the float valves in the center wing tank you must go through the center wing tank access door and the spanwise beam access doors.

 D.  
To get to the float valves in the No. 2 or 3 main tanks you must go into the main tank through access door 544AB or 644AB.

 TASK 28-15-11-004-001
 2.  Float Valve in the Center Wing Tank Removal (Fig. 401)___________________________________________
 A.  References
 (1)  
AMM 28-11-00/201, Fuel Tanks

 (2)  
AMM 28-11-09/401, Spanwise Beam Access Door

 (3)  
AMM 28-26-00/201, Defueling

 B.  
Access

 (1)  
Location Zones
 131 Center Section Wing Box, Left
 132 Center Section Wing Box, Right

 (2)  
Access Panels
 131EZ Center Wing Tank Access Door
 132CZ Center Wing Tank Access Door
 131AZ Spanwise Beam Access Door
 131BZ Spanwise Beam Access Door
 131CZ Spanwise Beam Access Door
 132AZ Spanwise Beam Access Door
 131DZ Spanwise Beam Access Door
 132BZ Spanwise Beam Access Door

 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-15-11
 ALL  ú ú 03 Page 401 ú Oct 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 C. Prepare for the Removal
 S 654-002
 (1)  Defuel the center wing tank (AMM 28-26-00/201).
 S 864-003
 WARNING:_______OBEY ALL THE FUEL TANK PURGING AND ENTRY PRECAUTIONS. YOU CAN CAUSE AN INJURY TO A PERSON AND CAUSE DAMAGE TO THE AIRPLANE.
 (2)  
Remove all the fuel in the center wing tank and prepare the center wing tank for an entry (AMM 28-11-00/201).

 S 864-004

 (3)  
Go into the center wing tank.

 S 014-027

 (4)  
Remove these spanwise beam access doors to get to the float valve on the left side of the center wing tank (AMM 28-11-09/401):

 (a)  
131AZ

 (b)  
131BZ

 (c)  
131CZ

 (d)  
131DZ

 S 014-033
 (5)  
Remove these spanwise beam access doors to get to the float valve on the right side of the center wing tank (AMM 28-11-09/401):

 (a)  
131AZ

 (b)  
131BZ

 (c)  
132AZ

 (d)  
132BZ

 D.
Remove the Float Valve(s)

 S 034-006
 (1)  
Disconnect or loosen the bonding jumpers and the tube support brackets if it is necessary.

 (2)  
Remove the lockwire from the coupling (two locations).

 S 034-030

 (3)  
Manually disconnect the couplings from the float valve.

 (a)  
Discard the O-rings (one O-ring per coupling).

 S 034-029
 EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú

 28-15-11
 ALL  ú ú 03 Page 402 ú Feb 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 S 034-031
 (4)  
Remove the bolt, washer and the nut (2 locations) from the float valve.

 S 024-032

 (5)  
Remove the float valve.

 S 394-069

 (6)  
Remove the unwanted sealant from the float valve area.

 TASK 28-15-11-404-072
 3.  Float Valve in the Center Wing Tank Installation (Fig. 401)________________________________________________
 A. Equipment
 (1)  
Bonding Meter (AMM 20-22-01/601)

 B.
Consumable Materials

 (1)  
D00128 Petrolatum - Technical, VV-P-236

 C.
References

 (1)  
AMM 20-11-15/401, Bonding Jumpers and Ground Leads

 (2)  
AMM 20-22-01/601, Electrical Bonding

 (3)  
AMM 28-11-00/201, Fuel Tanks

 (4)  
AMM 28-11-01/401, Center Wing Tank Access Door

 (5)  
　
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