S 796-184
(3)
Continue dye pressure until dye shows in the fuel tank.
S 796-185
(4)
Make a mark at the point where dye is first seen.
S 796-186
(5)
Remove the integral fuel tank leak tracing device.
S 166-250
(6)
Use a cloth and remove all the dye.
S 396-251
(7)
To repair or replace sealant, do this task: Repair of Sealant Leaks in the Fuel Tank Structure (AMM 28-11-00/801).
TASK 28-11-00-706-331
5. Helitest Leak Detection Procedure
_________________________________
A. General
(1)
This procedure uses the Helitest wing leak detection system to find the external and internal location of fuel leaks.
B.
References
(1)
AMM 20-30-82/201, Airplane Structure Cleaning Solvents (Series 82)
(2)
AMM 28-11-00/801, Fuel Tanks
(3)
AMM 28-26-00/201, Fuel Tank Defueling
C.
Consumable Materials
(1)
B01002 Solvent, General Cleaning of Solvent Resistant Organic
(2)
Coatings - Series 82 (AMM 20-30-82/201 or SOPM 20-30-82)
(3)
G50004 Tape, vacuum - SMS126 or SMS 127
(4)
G00252 Material, Plastic Sheeting (polyethylene) - L-P-512
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D. Equipment
(1)
HeliTest Wing Kit - Varian Vacuum Products, Inc. - 121 Hartwell Avenue, Lexington, MA 02173, Phone: 1-800-882-7426 (USA only)
(2)
Scissors - razor knife
(3)
Helium - compressed, industrial grade, standard cylinder
(4)
Regulator - pressure, and gage for helium cylinder
(5)
Ventilation equipment - positive and negative to control and evacuate helium
(6)
Source - compressed air, to blow areas dry
E.
Procedure
S 796-332
(1) Do these steps to find the external leaks and to make a map of them:
NOTE: You must make a precise map of the leaks for this procedure
____
to find the leakage.
(a)
Clean the external wing surface around the area where you think the leak is.
(b)
Use solvent to remove the grease from the area.
(c)
Dry the area.
(d)
Apply a mapping agent to the area. 1) Use talcum powder or a similar powder for a mapping agent.
(e)
For running leaks, do these steps: 1) Find the origin of the leak. 2) Stop the fuel flow with mastic or tape to make sure that
there are no other paths for fuel flow.
(f)
When the leak is found, remove the seat from the leak site and find the origin of the leak precisely within the seal.
S 656-333
(2)
Defuel or transfer fuel from the tank that has a leak
(AMM 28-26-00/201).
S 656-334
(3)
For the tank with the leak, do this task: Purging and Fuel Tank Entry (AMM 28-11-00/201).
S 796-335
(4)
Apply compressed air to the external leak point to force back the fuel faster and to dry the area.
S 796-336
(5)
Completely clean and dry the external leak point with solvent, Series 82 (AMM 20-30-82/201 or SOPM 20-30-82) to supply the best adhesion of tape.
NOTE: This step is important for successful leak detection.
____
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S 796-337
(6)
Do one of these two steps:
(a)
Build a custom compression chamber around the external leak point with a plastic film.
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