Thrush Aircraft S2RHG-T65 TURBO THRUSH Maintenance Manual page 14

THRUSH AIRCRAFT, INC – MODEL S2RHG-T65 TURBO THRUSH
AIRCRAFT MAINTENANCE MANUAL
boost pump.
The electrically driven fuel boost pump serves two purposes, first as a backup system to
provide continuous fuel pressure to the engine high pressure fuel pump in case the
engine driven fuel boost pump fails and secondly to provide boosted fuel pressure to the
engine high pressure fuel pump during engine starting. The electric driven fuel boost
pump discharge is then routed through a 25-micron main fuel filter to an engine driven
fuel boost pump.
The aircraft's fuel system is equipped with two fuel filters, a ¼ inch mesh finger strainer is
installed in the outlet fitting from the header tank and a 25-micron, airframe supplied, main
fuel filter located on the forward L/H side of the firewall. Fuel from the aircraft fuel system
enters the engines high pressure fuel pump which has two fuel filters of its own, an 74-
micron inlet filter and a 10-micron discharge filter (refer to the engine appropriate
maintenance manual for pertinent maintenance details for the engine supplied filters and
fuel system).
The fuel tank vent system is designed to keep the fuel spillage to a minimum. The fuel
tanks are vented through tubing connected at both the inboard and outboard ends of the
individual fuel tanks to the centrally located vent system in the fuselage. Ram air enters a
vent scoop, on the fuselage, under the left wing and pressurizes the vent system to
maintain positive pressure on the fuel tanks. The vent system is provided with two quick
drains, located on the fuselage under each wing, to drain any fuel that might happened to
have got in the tanks outboard vent lines.
At engine shutdown, fuel from the start control unit or the flow divider/dump valve, located
at the 6 o'clock position on the engine fuel nozzle manifold, is directed to a residue fuel
reservoir "EPA tank" mounted inboard on the L/H aft shin skin. This reservoir holds
approximately 3 engine shutdowns worth of fuel before the fuel will exit the reservoir vent
system. (NOTE: This reservoir should be emptied after each engine shutdown.) (NOTE:
It is common and normal after an engine compressor Water Wash or Performance
Recovery Wash to have water or soap appear in the reservoir's drained waste fuel.)
The fuel quantity gauge is located on the lower left instrument panel. The fuel quantity
indicating system consists of two transmitters, one indicator gauge, and an L/H or R/H
tank fuel quantity selector switch. A transmitter installed in each wing tank transmits an
electrical signal to the single fuel quantity indicator. The instrument reads both the left
and right fuel tanks singularly as chosen by the electrical control switch, adjacent to the
fuel quantity indicator gauge on the instrument panel.
The two fuel tanks are serviced through filler ports located on the top of both wings. The
filler ports incorporate security chains to prevent the loss of the fuel caps. Service the
aircraft from refueling facilities that utilize proper ground handling equipment and filter
systems to remove impurities and water accumulation from the bulk fuel. If filtering
facilities are not available, filter the fuel through a quality high-grade chamois. Fuel tanks
should be serviced after the last flight of each day to reduce condensation and allow any
entrapped water accumulations to settle to the fuel system drains, to be removed, prior to
the next flight.
Prior to the first flight of the day the header tank and fuel filter should be drained to check
for the presence of water or sediment in the fuel system. If there is a possibility, at any
time, that any tank may contains water, the header tank and fuel filter should be drained
as necessary to ensure no water exists in the fuel system. For fuel system servicing
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Effective: 05/05/04