REFUELING AIRCRAFT WITH
AUXILIARY POWER UNIT
The aircraft APU maybe used to supply electrical
power for pressure refueling on military aircraft so
equipped. Refueling with the APU running is not
conducted in the hangar deck. Although this operation
is not considered hot refueling, the following pre-
cautions must be observed, in addition to the normal
1. One person will be at the APU controls in the
2. Hand signals/signal wands must be established
between cockpit and personnel performing refueling to
ensure immediate shutdown in an emergency.
Defueling is one of the most technically demand-
ing and potentially dangerous operations performed
by fuels personnel. Most aircraft defueling equipment
can defuel an aircraft faster than the aircraft cart re-
lease it. The pumps discharge is throttled down to
balance its inlet (fuel from the aircraft) to prevent
pump cavitation and/or the loss of suction, which
would necessitate reflooding of the pump. Once the
proper balance is achieved, it is maintained by ma-
nipulation of the valve on the downstream side of the
pump throughout the defueling operation.
Defuelings normally have lower priority than re-
fueling. Unless otherwise directed and if they are not
of an emergency nature, defuelings will be by written
request approved by the Aircraft Handling Officer
(ACHO). A defuel request for an aircraft leaking fuel
is considered an emergency and handled promptly.
The following rules apply to every defueling op-
Aircraft defueling must be requested by an
authorized representative of the squadron by complet-
ing and submitting an Aircraft Defueling Certificate to
During defueling operations, no other mainte-
nance not directly required to aid the defueling opera-
tion is to be performed.
Fuel with a flash point below 140°F
SHALL NOT be defueled into the ships JP-5
system. These systems are not designed to han-
dle fuel with a lower flash point. The risk of
explosion and/or fire will significantly increase
if fuel with a low flash point is placed in these
All fuel removed from turbine engine aircraft is
assumed to be low-flash-point fuel. Defueled jet fuel
will NOT be returned to the ships JP-5 system without
first confirming the flash point of the fuel to be 140°F
Prior to any defuel, fuel will be tested for particu-
lates, free water, and flash point. Ultimate disposition
will depend on the results of subsequent laboratory
Additionally, JP-5 containing leak-detection dye
cannot be returned to a ships system.
If during the defuel operation the pump starts to
lose prime or cavitate, the operation will be discontin-
ued until the problem is resolved.
A special log of each defueling operation will be
maintained. The following minimum information is
contained in the log:
All abnormal happenings.
Aircraft Buno number.
Scheduled amount to be removed and amount
that was actually removed.
Disposition of product.
Time/date when the defuel operation was
started and completed.
Name of defuel operator and squadron
personnel present during the defuel operation.
Defueling crews must wear proper safety cloth-
ing and goggles.
Plane captains will be at their aircraft, and air-
craft engines stopped. All electronic and electrical
switches not required for defueling must be secured.