Record emergency fuel light time on DA Form 2408-13 block 17. When DA Form 2408-13 is re-
moved from the log book, transfer the emergency fuel data to DA Form 2408-15 for the engine and
record both that days light time on emergency fuel and a total light time on emergency fuel.
See footnote in Table 2-3 for limitations and precautions with emergency fuel.
DETECTION OF LEAKS.
a. Introduction. Dyed fuel may be used for static leak detection of JP-4 fuel cells and complete fuel systems.
Inlight tests to detect leaks, which cannot be detected by static or engine runup test may be used. However, the
use of inlight tests requires special approval of the maintenance oficer.
b. Preparation of Dye Solution. The quantities of liquid dye to be used and the mixing ratios are as speciied
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 insure proper mixing
of dye in fuel, partially ill 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 illed with remaining fuel.
d. Static Leak Detection in Fuel Cells. Use a diagram of the leaking fuel cell which shows all connections.
(1) Transfer the fuel into another cell or defuel as necessary. Pour the liquid dye into the leaking cell and ill
to the 1/3 level with JP-4 fuel.
One third level is determined from the known capacity of the cell; for example, 100 gallons added
to a 300 gallon cell.
(2) 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.
(3) 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.
(4) 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 connec-
(5) Check for defective cells (blisters, layer separations, etc.) in accordance with the applicable fuel cell
and/or aircraft maintenance manual.
(6) 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.
(7) After completion of fuel cell leak detection operation, the aircraft may be lown 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.