(2)  
Center Wing Vent System - Integral Center Tank (Fig. 601)

(a)  
Check that surge tanks and center wing tank are prepared for tank entry (Ref 28-23-0 and 28-10-0 MP).

(b)  
Remove left and right wing fuel tank access panels No. 13 and 14 (Ref 28-11-11 R/1).

(c)  
Remove center wing tank access panel to gain access to center tank cavities (Ref 28-11-31 R/I).

(d)  
Block off float valve, in center wing cavity No. 3, by installing a float valve closure plug, F80080-8, between valve float arm and float down stop.

(e)  
Block off two vent drain check valves, in center wing cavity No. 2, by installing two drain valve plugs, F80080-112 on lower end of valves.

(f)  
Plug forward vent tube in center wing cavity No. 1. 1) Remove bonding jumpers and uncouple center section vent tube (tee) from connecting LH and RH vent tubes. 2) Remove clamps holding center section vent tube to spanwise beam and remove bolt holding tube support bracket to stringer.  Remove tube.

3)  Install tube plug assemblies, F80080-49, in the two open ends of remaining LH and RH vent tubes.
28-13-0   Jun 20/92
Page 602
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

A37175
5C8  Fuel Vent System Pressure Check 
Aug 01/96  Figure 601  28-13-0 
Page 603 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

(g)  
Enter No. 1 wing tank through No. 1 panel and block off fuel scavenge jet pump nozzle by installing jet pump nozzle cover plug assembly F80080-131.

(h)  
Enter left wing surge tank through No. 13 panel and block off No. 1 tank vent duct (aft). 1) Install a structural vent plug, F8-0080-100 in outboard end of vent. 2) Install a structural vent cover assembly, F80080-56, in rectangular slot in vent

duct.

(i)  
Repeat step (h) above for right wing.

(j)  
Block off No. 13 panel opening in left or right wing by installing a surge tank pressure door assembly, F80080-82. Reinstall panel No. 13 in wing opposite to that chosen for pressure door assembly installation.

(k)  
Block off No. 14 panel opening in left wing by installing a vent scoop closure plug, F80080-88.

(l)  
Repeat step (k) above for right wing.

D.  Pressure Check Fuel Vent System
(1)  
Connect ground air supply and safety relief manometer to fittings on surge tank pressure door assembly, F80080-82.

(2)  
Fill manometer with water to 5.2 psi level (Fig. 602).

(3)  
Pressurize vent system to 5.0 +0.2 psi. Allow approximately 30 minutes for pressure and temperature to stabilize.

(4)  
Maintain 5.0 +0.2 psi on system and Check manometer for. pressure drop. Maximum allowable leakage is 1.0 inch of water in 15 minutes.

(5)  
If excessive pressure drop occurs indicating leakage, check that vent system closure items are installed satisfactorily and repeat step (4) above.

(6)  
If excessive leakage continues, check vent channel with a noncorrosive soap solution. Apply solution to outside of vent channel and appearance of bubbles should reveal the external leak point(s).

(a)  
Mark location of bubbles, remove bubble solution from surface with a damp rag, and depressurize vent channel.

(b)  
Repair leak (Ref 28-11-0 AR).

(c)  
Repeat pressure check to determine that leak has been eliminated.

(7)  
After completing check, remove all vent system closure items and restore system to normal configuration.

WARNING:  SERIOUS DAMAGE CAN OCCUR TO AIRPLANE STRUCTURE WHEN PERFORMING PRESSURE FUELING OPERATION IF VENT SYSTEM CLOSURE ITEMS ARE NOT REMOVED AFTER COMPLETING PRESSURE CHECK.

(8)  
Install center section vent tube in center wing cavity No. 1. Ensure that O-ring seals are installed before connecting tube couplings. Install clamps, bracket bolt, and bonding jumpers.

(9)  
Check electrical bond between center section vent tube and connecting tube per 20-22-01 I/C. Resistance shall not exceed 0.010 ohm.

(10)
Ensure that tools and equipment are removed from all tanks.

(11)
Install fuel tank No. 1 and 2 access panels (Ref 28-11-11 R/I).

(12)
Install center wing tank access panel (Ref 28-11-31 R/I).

594 
28-13-0  Page 604  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/92 

F95050
593  Water Safety Relief Manometer Assembly 
May 20/82  Figure 602  28-13-0 
　
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