Engine operation using only the engine-
driven primary (high-pressure) fuel pump
without standby fuel pump or engine-
driven boost pump fuel pressure is limited
to 10 cumulative hours. This condition is
indicated by illumination of either #1 or #2
illumination of the master warning light on
the glare shield. Refer to Chapter 9. All
time in this category shall be entered on
DA Form 2408-13-1 for the attention of
a. Fuel Tanks. The main wing tanks consist of
two leading edge tanks, two box section bladder tanks,
and an integral (wet cell) tank all interconnected to
flow into the nacelle tank by gravity. This system of
tanks is filled from the filler located near the wing tip.
The auxiliary fuel system consists of a center section
tank, located in the inboard wing, with its own filler
opening and an automatic fuel transfer system to
transfer the fuel into the nacelle tank. An anti-siphon
valve is installed at each filler port to prevent loss of
fuel or collapse of a fuel cell bladder in the event of
improper securing or loss of the filler cap. The nacelle
tank is located directly behind the engine and contains
a submerged, electrically operated standby fuel pump.
The fuel from the nacelle tank is fed directly into the
engine by either the engine-driven primary fuel pump
or, as backup, the standby fuel pump. The quantity of
fuel for the tanks is detailed in Table 2-3.
b. Engine Driven Boost Pumps. A gear-driven
boost pump mounted on each engine supplies fuel,
under pressure, from the nacelle tank to the inlet of the
engine-driven primary high-pressure pump for engine
starting and all normal operations. Either the engine-
driven boost pump or stand by fuel pump is capable of
supplying sufficient pressure to the engine-driven
primary high-pressure pump and thus maintain normal
c. Standby Fuel Pumps. A submerged,
electrically operated standby fuel pump, located within
each nacelle tank, serves as a backup unit for the
engine-driven boost pump. The standby pumps are
switched off during normal system operations. A
standby fuel pump will be operated during crossfeed to
pump fuel from one system to the other. The correct
CROSSFEED switch is activated. Each standby fuel
pump has an inertia switch included in the power
supply circuit. When subjected to a 5 to 6 G shock
loading, as in a crash situation, the inertia switch will
remove electrical power from the standby fuel pump.
The standby fuel pumps are protected by two 10-
ampere circuit breakers, placarded STANDBY PUMP
1 or 2, located on the overhead circuit breaker panel,
and four 5-ampere circuit breakers wired (two each in
parallel) on the hot battery bus.
Table 2-3. Fuel Quantity Data
(Ferry tank) ***
(Ferry tank) ***
*(TOTALS with Ferry tanks installed)
* Unusable fuel quantity and weight (4 gallons, 26 pounds not included in totals).
** Fuel weight is based on standard day conditions at 6.8 pounds per U.S. gallon. Total fuel system
capacity, without ferry fuel, is 548 gallons.
*** Data for ferry tanks is included when they are installed.