(d)  
If the leak is near the side-of-body rib, remove the necessary panels to get access to the external part of the fuel tank.

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 (e)  
If there is leakage from the upper surface of the wing center section, look for leakage in the fillet seals in the upper surface of the wing center section, and for leakage through the secondary fuel barrier on top of the wing center section.

 (f)  
Rub the area that has the leak with cotton cloth to dry it.

 (g)  
Use a camel hair brush or a squeeze bottle to apply talcum powder to the area of the skin that contains the leak.

 (h)  
Monitor the talcum powder continuously to see where it changes color.

 (i)  
Compare the dimensions of the leak with the dimensions shown in Fig. 602 to find the type of leak.

 NOTE: Monitor the leak area with the talcum powder for
____ fifteen minutes to make sure you have the correct leak type and the correct leak position.
 (j)  If the talcum powder starts to change color at the edge of the area where you applied it, apply more talcum powder at that edge.
 NOTE: If the talcum changes its color (becomes wet) at a
____ different location, it is possible that that location is also important to the leak path. For example, there can be indications of a leak at a lockbolt or a rivet installation. Leaks in the bottom of the wing around access doors are usually caused by a bad O-ring in the access door.
 (k)  Make a mark that you can see easily at the location of all external leaks.
 S 366-270
 (2)  
Refer to Fig. 602 to find if the leakage must be monitored or repaired.

 (3)  
To repair the leakage, do the subsequent procedures.

 S 366-269
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 S 286-034
 (4)  If you find the external leak in a location that has aerodynamic smoother, remove some aerodynamic smoother around the area of the leak (AMM 51-31-00/201).
 NOTE: It is a good procedure if the hole in the smoother is
____ approximately the same as the dimensions of the nozzle that you use for the backblowing procedure.
 S 286-035
 (5)  Do not defuel the fuel tanks until you know the exact location of all leaks on the airplane skin.
 H. Use the Backblowing Procedure to Find the Internal Leaks
 S 656-036
 (1)  Defuel the applicable fuel tank(s) (AMM 28-23-00/201).
 S 016-037
 WARNING: CAREFULLY DO ALL OF THE SAFETY PROCEDURES IN THE PURGING AND
_______ ENTRY PROCEDURE FOR THE FUEL TANK. INJURY TO PERSONS AND DAMAGE TO EQUIPMENT CAN OCCUR.
 (2)  
Do this task: "Fuel Tank Purging and Entry" for the tank that has the leak (AMM 28-10-00/201).

 S 946-038

 (3)  
Two persons are necessary to do this task:

 (a)  
One person must be out of the tank at the external location of the leak.

 (b)  
One person must go into the tank and find the internal location of the leak.

 (c)  
If the leak external leak location is near the side-of-body rib, the leak can be in the center tank or the wing tank.

 NOTE: It is a faster procedure to put a person in the
____ center tank and in the wing tank at the same time to look for the internal leak.
 S 946-039
 (4)  The two persons must agree on a procedure to communicate.
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