General Description - Thrush Aircraft S2R–T660 Maintenance Manual

THRUSH AIRCRAFT INC - T660 TURBO THRUSH
AIRCRAFT MAINTENANCE MANUAL
FUEL SYSTEM
SECTION FIVE

GENERAL DESCRIPTION

A 230 U.S. gallon fuel supply is available for the Thrush S2R-T660. In each wing, fuel is contained
inside integral wing tanks (wet wing fuel tanks) just outboard of the center section sub-wings. The
left wing and right wing fuel tanks are interconnected through a 5 U.S. gallon header tank that is
located in the fuselage. The fuel supply lines, to the engine, are routed from the header tanks outlet
finger screen through a fuel shutoff (on/off) valve to an electric driven fuel boost pump. 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 electric driven fuel boost pump serves two purposes, first as a backup
system to provide continuous fuel pressure to the engines high pressure fuel pump in case the
engine driven fuel boost pump fails and secondly to provide boosted fuel pressure to the engines
high pressure fuel pump during engine starting. 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, an 74-
micron inlet filter and a 10-micron discharge filter (Refer to the engines appropriate maintenance
manual for pertinent maintenance details for the engine supplied filters and fuel systems). 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 drain, 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 flow divider/dump valve, located at the 6 o'clock position on the engines 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 reservoirs' vent
system. (NOTE: This reservoir should be emptied after each 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 reservoirs' drained waste fuel.) The fuel quantity gauge is located on the lower
left instrument panel. The fuel quantity indicated system consists of two transmitters, one indicator
gauge, and a 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
5 -2
Effective: 12/17/03