Specifications

SECTION II
MODEL 560 AIRPLANE AND SYSTEMS
ENGINE FUEL SYSTEM
The two-stage, engine-driven pump mounted on the accessory gearbox supplies high pressure flow to
the fuel control unit. Fuel enters the pump at 20-30 PSI from the primary ejector pump. The engine-driven
pump increases this pressure to 500-1250 PSI. Part of the pump output is bypassed through the motive
flow valve to drive the primary ejector pump and the remainder is directed downstream to the fuel control.
This positive pressure to the fuel control must be maintained by the engine-driven pump for the engine to
continue to operate.
The fuel control unit is mounted on the engine-driven fuel pump and determines the proper fuel
schedule for all phases of engine operation.
A flow divider downstream of the fuel control unit provides proper fuel distribution to the combustion
chamber by dividing the flow from the fuel control between the primary and secondary fuel manifolds.
Each side of the fuel system incorporates quick drains.
FILTER
Each side of the fuel system incorporates quick drains and an engine mounted filter. In addition, inlet
screens are installed on the fuel sump structure and all of the transfer ejector pump inlets. A pressure
differential sensing switch and a bypass valve alert the pilot and allow flow to continue should the filter
become obstructed. The switch closes and illuminates the FUEL FLTR BP annunciator panel light if the
difference between filter inlet and outlet pressure reaches 22 PSI, ±2.0. The bypass valve opens at 28 PSI
to bypass the obstructed filter. Illumination of the annunciator panel light indicates impending or actual
bypass of fuel around the filter.
FLOW INDICATORS
Fuel flow rate is measured downstream of the fuel control and presented on a digital format gauge in
pounds per hour per engine.
QUANTITY INDICATORS
Six capacitance-type probes and one temperature compensator in each cell supply information to the
Fuel Quantity Signal Conditioner (FQSC). The FQSC converts these signals into voltage and transmits the
signal to the vertical scale quantity indicator, which displays the fuel quantity in pounds.
LOW LEVEL WARNING
Low level warning functions independently of the normal quantity indicating system and provides a
visual warning to the crew when a minimum amount of usable fuel remains in either tank. The system
consists of a float switch in each fuel cell and L and R LO FUEL LEVEL annunciator panel lights. A
minimum usable fuel quantity of 180 ± 20 pounds in either tank will illuminate the associated light. When
operating with light fuel loads, it is possible for the lights to illuminate momentarily in turbulent flight
conditions or while taxiing on rough surfaces. The system is calibrated to give an accurate indication in
level unaccelerated flight.
FUEL SHUTOFF
Electrically operated firewall shutoff valves can be individually closed by depressing the LH or RH
ENG FIRE button. Actuation of a shutoff valve will be indicated by illumination of the respective L or R F/W
SHUTOFF annunciator panel light. Protection against severe overspeed or explosive structural failure of the
engine is provided by an automatic fuel shutoff. It is actuated through a mechanical linkage should a 0.053
± 0.002 inch rearward displacement of the turbine shaft take place. Fuel flow to the manifold is terminated,
automatically shutting down the engine. A manual shutoff is located in each wing root for use by
maintenance personnel.
I 56OMB-01 Configuration AA 2-17