REVIEW SUBSET NUMBER 6
Fuel level sensors control the fuel level in tanks
2 and 3 (engine feed tanks) during fuel transfer
from tanks 1 and 4. All internal and external fuel
Q1. The circuit that differentiates between an
(except engine feed tanks) can dump overboard
overtemp (fire} and a short circuit in afire
through flame arrester protected outlets in each
warning system is known as a
vertical fin. All internal fuel tanks vent through
outlets in the vertical fins. The external tanks
vent overboard through pressure relief valves
in the individual external tanks. A fuel quantity
indicating system provides fuel quantity indi-
cations in pounds.
Q2. The fire warning element has an inverse
temperature coefficient. What does this
statement mean?
FEED TANKS
The internal transfer system design keeps fuel
in the feed tanks (tanks 2 and 3) at all engine
Q3. In the fire warning circuit (fig. 5-12), what
power settings. Fuel being transferred from tanks
happens when Q6 switches before Q1?
1 and 4 flows to the feed tanks, where the fuel
level is maintained by fuel level sensors.
WING TANKS
Q4. What chemical is used in the engine
extinguishing system HRD bottles?
Wing tanks transfer fuel to tanks 1 and 4.
They are an integral part of the wing structure.
Wing tanks are sealed by filling channels with
sealant injected through fittings on the outside of
the wings.
FUEL TRANSFER SYSTEMS
TRANSFER MOTIVE FLOW
Learning Objective: Recognize operating
parameters and characteristics of aircraft
The internal fuel transfer system is powered
fuel transfer systems.
by motive flow pressure, generated by two
airframe-mounted accessory drive-mounted
The F/A-18 aircraft fuel transfer system is
(AMAD) motive flow/boost pumps contained in
described in this section of the TRAMAN. The
a closed loop circuit.
F/A-18 carries fuel internally in four
Flow pressure passing through the left and
interconnecting fuselage (bladder) tanks and two
right engine motive flow check valves combines
internal wing (wet) tanks. External fuel is carried
to create transfer motive flow pressure. Transfer
in three 315- or 330-gallon tanks. All tanks may
motive flow pressure operates the wing transfer
be refueled on the ground through a single-point
ejectors and tanks 1 and 4 transfer jet ejectors.
refueling receptacle. Airborne, they can be
Transfer motive flow pressure also closes the
refueled through the in-flight refueling probe. The
refuel/defuel shutoff valve and defuel valve.
internal wing tanks--tank 1 and tank 4--are
transfer tanks. The tanks are arranged so internal
WING TRANSFER
fuel gravity transfers (at a reduced rate) even if
the transfer jet ejectors fail. Regulated engine
Wing transfer starts when the fuel level drops
bleed air pressure is used to transfer fuel from the
external tanks and also provides a positive
below the high level pilot valves in tanks 1 and/or
4. This opens the fuel level control shutoff valve,
pressure on all internal fuel tanks. Float-type fuel
level control valves control fuel level during
allowing the wing transfer jet ejectors to transfer
refueling of all tanks. Fuel level control shutoff
fuel through the refuel/transfer manifold. As the
valves in tanks 1, 2, 3, and 4 control fuel levels
fuel level in the wings drops below the transfer
during external fuel transfer. During internal wing
motive flow pilot valves, the wing transfer motive
transfer, fuel level control shutoff valves control
flow shutoff valves close, stopping transfer from
the wings. Refuel/transfer check valves in tanks
fuel levels in tanks 1 and 4.
