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FUEL PRESSURE GAUGE:  Scale is 0-30 psi.  Normal range is 4-30 psi.  A fuel pressure transducer sends a signal to the gauge.  NOTE: VHF transmission may cause pressure gauge to fluctuate if helo has a solid state fuel pressure transducer due to EMI.

FUEL BOOST PUMP PRESSURE SWITCH: 1 on each boost pump; activates fuel pump caution light if pump pressure falls below 3.5 psi.

AIR FRAME FULTER CARTUIN LIGHT:  When differential pressure is sensed across the airframe fuel filter the caution light comes on to warn the pilot of an impending bypass.

LOW FUEL CAUTION LIGHT:  Comes on when fuel is approximately 20 gal.


Identify the components and characteristics of the fuel quantity measuring system.

2 float type sensors provide inputs to a single fuel quantity indicator (calibrated in gallons, 0-100)

1 float typw switch activates fuel low caution light when fuel drops to approximately 20 gllons.


State how the pressure indicating system works to relay fuel pressure information to the pilot.

Fuel pressure transducer, located between boost pumps and fuel shutoff valve, sends a signal to cockpit to indicate fuel boost pressure.  (28 vdc)


State how shut-off power works to permit or restrict fuel flow.

28 vdc system.  Shutoff valve is located in main fuel supply line in fuel compartment just above fuel filler cap.  Controlled by cockpit switch.  When DC power is lost the valve stays in the last energized position.


State the location of the airframe fuel filter and identify the functions of its components.

Located on STBD side, aft of the forward firewall and consists of:  Replaceable filter element, drain valve, bypass valve, impending bypass switch, manual test button.


State the operational characteristics of the engine fuel pump/ filter.

Delivers filtered fuel at 650-750 psi to the fuel control unit.  NOTE: Fuel enters pump housing and passes through a low pressure filter (4-30 psi) and then to the gear type pump which pressurizes the fuel to 650-750 psi and delivers it to the FCU.  The internal filter will bypass if clogged but there is no indication until maintenance inspects the filter.  The FCU meters the proper amount of fuel and sends it to the fuel nozzle.  Any excess fuel hot needed by the fuel control unit is returned to the engine driven fuel pump.


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