LOCATION AND DESCRIPTION OF MAJOR COMPONENTS (cont)
(2) Fuel Level Control Valve.
A fuel level control valve, located in each fuel cell, automatically shuts off
fuel flow into the fuel cell when it reaches capacity during pressure refueling or fuel transfer. The fuel level control
valve consists of a pilot valve, a fuel shutoff valve, a pilot valve tube, and an isolation switch (not shown). The pilot
valve contains a gravity ball valve, a fuel float valve, and a solenoid-operated poppet valve.
(3) Fuel Vent Shutoff Valve.
When open, the fuel vent shutoff valve allows air trapped in the top of the
fuel cells to be vented overboard during refueling. When closed, the valve prevents loss of nitrogen during
(4) Pressure Fuel Manifold.
The pressure fuel manifold, mounted on the right side of the fuselage
forward of the wing, houses the single point adapter (SPA) and the closed circuit adapter (CCA). Each adapter
has a spring-loaded check valve that is forced open when the fuel nozzle is connected.
(a) The SPA is used in the continental United States (CONUS) and United States bases outside
CONUS. It allows a refueling rate of 100 gpm.
(b) The CCA is for used at North Atlantic Treaty Organization (NATO) bases. It allows a refueling rate of
(5) Fuel Transfer (Refuel) Valve.
The fuel transfer (refuel) valve, located on the upper right side of the
ammunition bay, is open only during refuel or defuel operations and allows pressure refueling and suction
defueling of the aft tank. It is a motor-operated valve requiring 24 VDC for operation and is controlled by the
REFUEL VALVE switch on the refueling panel.
(6) Air Vent/Pressure Relief Valve.
The air vent/pressure relief valve equalizes pressure inside the fuel
cell by venting excess pressure overboard to prevent overexpansion of the fuel cells. It also vents excess fuel
overboard in the event of automatic fuel shutoff failure and prevents fuel leakage in the event of a rollover. The air
vent/pressure relief valve port vents the fuel cell during NIU operation.
g. Auxiliary Fuel System.
The auxiliary fuel system (fig. 107) consists of the auxiliary fuel tanks, the
auxiliary fuel tank empty switches, the auxiliary fuel tank air shutoff valve, the auxiliary fuel tank fuel shutoff
valves, and the auxiliary fuel system check valves.
(1) Auxiliary Fuel Tanks (2 or 4).
The auxiliary fuel tanks are carried on the wing pylon attachment
points. There are provisions for as many as four external fuel tanks. The auxiliary fuel tanks are made of
aluminum alloy and are individually refueled via a gravity filler port.
(2) Fuel Empty Switches.
One fuel empty switch is mounted inside each auxiliary fuel tank and provides
a visual indication when the auxiliary fuel tanks are empty by illuminating the EXT EMP indicator on the pilot
caution/warning panel. The fuel empty switch is a float switch that completes a circuit when the fuel level is below
the float. The fuel empty switches are connected in a series so that all tanks must be empty before the electrical
circuit for the pilot caution/warning panel is signaled.
(3) Auxiliary Fuel Tank Shutoff Valves.
The auxiliary fuel tank shutoff valves are located in the trailing
edge of each wing when the auxiliary tank kit is installed on the helicopter. They provide positive fuel shutoff when
the pilot FUEL panel EXT TK transfer switch is placed in the OFF position and prevents air from being drawn from
the auxiliary tanks during internal fuel system transfer.
(4) Auxiliary Fuel Tank Air Shutoff Valve.
The auxiliary fuel tank air shutoff valve, mounted on the left
side of the aft equipment bay, controls airflow that is used to transfer fuel from the auxiliary tanks to the internal
cells. The auxiliary fuel tank air shutoff solenoid valve is spring-loaded closed and electrically opened. The valve
has an electrical receptacle, an air inlet port and an air outlet port.