TM 1-1520-238-T-7
10–10
10–2.
LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (cont)
10–2
c. Fuel Quantity Indication/Transfer System. The fuel quantity indication/transfer system (fig. 10–3)
consists of the pilot and CPG FUEL panels, the pilot fuel quantity indicator, the CPG selectable digital display, the
signal data converter (SDC), the fuel signal conditioner (FSC), the fuel transfer pump, the fuel transfer air valve,
and fuel quantity transmitters.
(1) Pilot and CPG FUEL Panels.
The pilot and CPG FUEL panels are located in the left console each
crew station. The fuel TRANS switches gives the pilot and CPG a means of controlling fuel transfer. Selecting TO
FWD will transfer fuel from the aft fuel cell to the forward fuel cell; selecting TO AFT will transfer fuel from the
forward cell to the aft cell.
(2) Pilot Fuel Quantity Indicator.
The pilot fuel quantity indicator, located in the left side of the pilot’s
instrument panel, has two side-by-side vertical scale displays and a TOTAL digital readout display under the
scales. Fuel quantity in the aft fuel cell is displayed on the right scale, fuel quantity in the forward fuel cell is
displayed on the left scale. Total fuel quantity of the two fuel cells are displayed on the TOTAL digital readout
display.
(3) CPG Selectable Digital Display.
The CPG selectable digital display, located in the right-hand center
of the CPG instrument panel, provides the CPG with selection of engine instrument and fuel quantity data
displays.
(4) SDC.
The SDC, located on the left side of the aircraft nose behind access door L40, contains two
power supplies and an internal fuse panel. The fuse panel protects all instruments from overload. The SDC
receives 28 VDC from dc buses 1 and 2 and reduces this voltage for operation of the instrument system. The
SDC routes operating power to the FSC except during refueling. The SDC also receives a signal from the low
level sensors, processes the signal, and applies it to the pilot and CPG caution/warning panels.
(5) FSC.
The FSC, located on the left side of the aircraft nose behind access door L40, converts aft and
forward fuel quantity transmitter inputs to linear zero to 5 VDC to drive the fuel quantity indicators (pilot fuel
quantity indicator and CPG selectable digital display). The FSC consists of a power supply, an oscillator, two
signal conditioners (one for each fuel cell), and four screw adjustments used to adjust fuel and empty indications
on the pilot fuel quantity indicator.
(6) Fuel Transfer Air Valve.
The fuel transfer air valve, located in the upper right side of the ammunition
bay, controls air to the air-driven fuel transfer pump.
(7) Fuel Transfer Pump.
The fuel transfer pump, located in the upper right side of the ammunition bay,
pumps fuel from one fuel cell to the other. It consists of an air-driven motor and a pump.
(8) Fuel Quantity Transmitters.
The fuel quantity transmitters electronically measure the quantity of fuel
in the forward and aft fuel cells. The forward fuel cell has two fuel quantity transmitters. The aft fuel cell has one
fuel quantity transmitter. The aft transmitter in the forward fuel cell and the transmitter in the aft fuel cell each have
a low fuel level sensor. An analog signal is sent from the transmitters to the SDC where it is converted to a digital
signal and amplified before going to the indicators. All of the fuel quantity transmitters have fuel quantity
compensators to compensate for different fuel densities.
