TM 1-1500-204-23-3
Table 2-7. Mixing Ratios
Liquid dye
NSN
Unit of issue
MIL-SPEC
Mixing ratio
Static Fuel System Tests
Red
6820-00-926-8887
2 ounces
MIL-D-81298
Add 2 ounces
Red
6820-00-001-4192
1 gallon
MIL-D-81298
to each 100
Yellow
6820-00-412-2296
1 gallon
MIL-D-81298
gallons of fuel.
Runup and In-flight Fuel System Tests
Yellow
6820-00-412-2296
1 gallon
MIL-D-81298
Add 1.6 ounces
to each 100
gallons of fuel.
(c) Mixing in servicing vehicle. The dye can be blended in a refueling vehicle that has been reserved for
servicing dyed fuel. The required quantity of dye should be determined before starting. To ensure proper mixing of dye
in fuel, partially fill the trailer to about 10 percent and then add the appropriate amount of dye slowly to the contents of
the trailer while the trailer is filled with remaining fuel.
(d) Static leak detection in fuel cells. Use a diagram of the leaking fuel cell which slows all connections.
1 Transfer the fuel into another cell or defuel as necessary. Pour the liquid dye into the leaking cell
and fill to the 1/3 level with JP-4 fuel. Allow the dye solution to set in the cell for approximately 6 hours or until the dye
solution comes through the drain. Should the dye appear, there is a leak within this level.
NOTE
One third level is determined from the known capacity of the cell; for example, 100
gallons added to a 300 gallon cell.
2 Repeat the procedure at the 2/3 level and full level, as necessary. A full cell should be allowed to set
for approximately 12 hours.
3 When a leak is detected, connections should be checked, the cell defueled, and residual fuel
removed with cloths and drained from the sump. Type MA-1 explosion proof blower may be used to remove fumes.
Remove all connections, pull fuel cell down, and check for dye stains on exterior of the cell. These stains are easily
detected, thus pinpointing the leak. Rarely is any maintenance necessary other than replacing seals and retorquing
connections.
4
Check for defective cells (blisters, layer separations, etc.) in accordance with the applicable fuel cell
and/or aircraft maintenance manual.
5
After closing the fuel cell, the dye solution may be transferred into the fuel cell once more to the
three levels: 1/3, 2/3, and full, thereby ascertaining whether or not the cell still leaks.
6
After completion of fuel cell leak detection operation, the aircraft may be flown with yellow dyed fuel.
Red dyed fuel can be used provided it is diluted 10 parts to 1 part with undyed fuel in the fuel cell or cells. If dilution is
not possible, the aircraft will be defueled of dyed fuel which will be stored in a bulk storage tank.
(e) Static leak detection for fuel system including lines and engines. Leakage checks of airframe mounted
lines and connectors, and of integral wing and auxiliary fuel tanks may be undertaken using any of the dyes authorized
herein. However, when red dye is used the engine shall not be operated, and the aircraft shall be defueled of the dye
fuel following testing. Residual yellow dyed fuel need not be removed.
(f) Static-leak detection in airframe lines and fuel cells. If only the airframe mounted fuel lines and
connectors, or integral wing and auxiliary fuel cells are to be tested, allow the dyed fuel to stand in the aircraft 6 to 8
hours before performing leakage testing.
2-29
