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757
MAINTENANCE MANUAL

 (b)  
Sealants are supplied in two parts; base material and accelerator. You must be very careful to make sure the correct proportions of the base material and the accelerator recommended by the manufacturer are used. If you do not obey the manufacturer's instructions you can change the physical properties of the mixture which can cause a seal failure and a fuel tank leak.

 (c)  
Sealing compounds have a specified shelf life. After the specified time, you must do a test of the sealing compounds to find out if you can use them.

 (d)  
You can keep some sealants in refrigeration for a short time after they are mixed with the accelerator. You must discard these sealants after the specified time.

 S 288-004
 (3)  
Sealants are applied incorrectly.

 (a)  
If you do not do the subsequent steps, fuel leaks can occur: 1) Follow all manufacturer's instructions. 2) Use a brush to apply precoat when recommended. 3) Do all the steps to apply the sealant. 4) Make sure there are no air bubbles in the sealant. 5) Make sure you fill all the spaces completely with sealant. 6) Make sure you do not make an overlap with the sealants. 7) Make sure the sealant touches all the surfaces.

 S 288-005
 (4)  
The fasteners are loose.

 (a)  
Loose fasteners start fuel leaks because they let attached surfaces move. 1) Faying surface seals get cracks and let fuel leak through

 the seal plane.

 (b)  
Loose rivets are not self-sealing.

 (c)  
Sealant or metal seal covers do not bond with loose fasteners.

 S 288-006
 (5)  
Fittings and connections are installed incorrectly.

 (a)  
Fittings and connections attached to or that go through the fuel tank structure are sealed with O-rings. Damaged or incorrectly installed O-rings can cause fuel leaks.

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757 MAINTENANCE MANUAL
 TASK 28-11-00-308-032
 4.  Repair of Sealant Leaks in the Fuel Tank Structure__________________________________________________
 NOTE: To seal dry bay access panels, refer to AMM 51-31-01/201.
____
 A. General
 WARNING:_______MAKE SURE YOU HAVE GOOD FLOW OF AIR IN THE AREA. OBEY ALL FIRE SAFETY PRECAUTIONS. POISONOUS AND FLAMMABLE MATERIALS ARE USED THAT CAN CAUSE INJURY TO PERSONS AND DAMAGE TO EQUIPMENT.
　
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