FUEL VENT FLOAT VALVE - REMOVAL/INSTALLATION
WARNING:  COMPLY WITH ALL TANK ENTRY PRECAUTIONS (REF 28-10-0, MAINTENANCE PRACTICES).
1.  Remove Fuel Vent Float Valve (Fig. 401)
A.  Defuel and purge fuel tank (Ref 28-23-0, 28-10-0, Maintenance Practices).
B.  Remove fuel tank access panels as necessary to gain access to float valve (Ref 28-11-11  or 28-11-31, Removal/Installation).
C.  Remove bolts securing float valve to structure.
D.  Remove float valve.
2.  Install Fuel Vent Float Valve (Fig. 401)
A.  Install O-ring in O-ring groove on float valve.
B.  Hold float valve in position and install bolts.
NOTE: Assure that no color coding tape is left on any component within the fuel tank.
C.  Check tank for cleanliness.
D.  Install access panel(s) (Ref 28-11-11 or 28-11-31, Removal/Installation).
543 
May 1/74  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  28-13-11 Page 401 

Fuel Vent Float Valve Installation  5C8 
28-13-11 Page 402  Figure 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  May 01/01 

CENTER WING CAVITY - INSPECTION/CHECK
1.  APU Shroud and Fuel Line Shroud Drain System Check
A.  General
(1)  
A drain cock for the APU shroud and fuel line shroud drain system is located in the drain line in the left main wheel well immediately upstream from the flame arrestor. The drain cock must be opened periodically to check for accumulated fluids not discharged through the drain mast.

(2)  
The APU shroud and fuel line shroud drain system flame arrestor can be cleaned by removing the unit and immersing it in a mild cleaning bath and using an air gun to free any clogged cells.

B.  Check Drain System
(1)  
Gain access to drain cock through left main wheel well.

(2)  
Open drain cock and allow accumulated fluids to discharge.

(3) 
 Close drain cock.

F94738
5C8  APU Shroud and Fuel Line Shroud Drain System 
Aug 01/96  Figure 601  28-13-21 
Page 601 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

AIR VENT SCOOP FLAME ARRESTOR - REMOVAL/INSTALLATION
1.  General
A.  A cellular-core, stainless steel flame arrestor unit is installed on the top flange of the air vent scoop access panel air stack (Fig. 401). If the flame arrestor cells are clogged with dirt and foreign matter the flame arrestor can usually be cleaned, without removing the arrestor, by immersing the whole access panel assembly into a mild cleaning bath and using an air gun to free any clogged cells.
B.  If it is necessary to remove the flame arrestor, the mounting flange must be resealed upon reinstallation.
2.  Equipment and Materials
A.  Solvent - Methyl ethyl ketone (MEK), TT-M-261
B.  Sealant removal, cutting, and fairing tools (Ref par. 3.A., 28-11-0, Approved Repairs)
C.  Sealant - BMS 5-26, Type II, Class A
D.  Sealant - BMS 5-26, Type II, Class B
E.  Sealing gun or tube for applying fillet sealant material
F.  Paint brush, smal1
3.  Remove Flame Arrestor
A.  Ensure the airplane is adequately grounded to an approved and identified ground.
B.  Unless fuel tank is defueled and purged, perform the following safety checks: 
(1)  
Remove electrical power from airplane and do not restore power until fuel tank is closed and safe. 

(2)  
Disconnect battery and attach sign which reads, OPEN FUEL TANKS - DO NOT CONNECT. 

(3)  
Rope off area around outboard section of wing and post clearly visible signs which read DANGER - OPEN FUEL TANKS. 

(4)  
Ensure there is no residual fuel in surge tank by opening sump drain and draining any remaining fuel into a suitable container.

C.  Remove air vent scoop access panel (Ref 28-11-11, R/I).
D.  Using sealant cutting and removal tools, strip sealant from around flame arrestor mounting flange.
E.  Remove flame arrestor attaching bolts and discard seal washers.
Aug 15/76 28-13-31 Page 401 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

4.  Install Flame Arrestor (Fig. 401)

A.  Remove any remaining sealant and thoroughly clean mounting flanges using a clean, lint-free cloth moistened with MEK solvent.
WARNING:  METHYL ETHYL KETONE (MEK) IS TOXIC. USE ONLY IN WELL-VENTILATED AREA.
　
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