(e)  
Disconnect the vacuum source from the drain hole.

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A

757 MAINTENANCE MANUAL
 (f)  Do the steps to find the correct location of the leak by the air pressure and bubble method again.
 TASK 28-11-00-216-064
 7. Leak Path Analysis
__________________
 A. Access
 (1)  
Location Zones
 133 Wing Center Section (Left)
 134 Wing Center Section (Right)
 531 Center Wing Tank (Left)
 541 Main Tank-Rib No. 5 to No. 17 (Left)
 542 Main Tank-Rib No. 17 to No. 21 (Left)
 543 Surge Tank-Rib No. 21 to No. 23 (Left)
 631 Center Wing Tank (Right)
 641 Main Tank-Rib No. 5 to No. 17 (Right)
 642 Main Tank-Rib No. 17 to No. 21 (Right)
 643 Surge Tank-Rib No. 21 to No. 23 (Right)

 B.
Procedure

 S 216-065
 (1)  
After you find the external leak point and the internal leak source, find the point where fuel goes through the seal plane.

 (a)  
The internal area where you see the bubble or dye usually shows the point where fuel goes through the seal plane.

 (b)  
If there is an injection, prepack or hidden seal failure, the fuel goes into and moves in the tank structure and shows at a point far from the leak source.

 (c)  
If you repair the internal area where you see the bubble or dye and do not repair the injection, prepack or hidden seal failure, you can only temporarily repair the leak.

 (d)  
You must find all possible leak paths between the external leak point and internal leak source to repair the seal failure.

 NOTE: You can raise the seal plane as an alternative to a
____ repair of the seal (AMM 28-11-00/601).
 (e)  When there is a seal plane failure, the faying surfaces of the fuel tank structure, external to the seal plane, get wet.
 NOTE: The area that gets wet extends in all directions from
____ the point fuel goes through until it finds an injection, faying surface, prepack or hidden seal. The seal plane stops the release of fuel from the fuel tank.
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