(FOR REMINDER ONLY) FUEL SYSTEM SUMMARY ENG TRENT 700 скачать в хорошем качестве

(FOR REMINDER ONLY) FUEL SYSTEM SUMMARY ENG TRENT 700

The engine fuel system is designed to supply metered fuel to the combustion chamber according to the engine power demand. The fuel system is also used to cool the engine oil and supply servo pressure to operate valves and actuators. The Engine Electronic Controller (EEC) controls the operation of the engine fuel system. The EEC also monitors the system for normal operation and ECAM fuel flow indication. LOW PRESSURE FUEL The low pressure (LP) valve controls the fuel supply from the aircraft tanks to the engine fuel pump. The engine fuel pump includes an LP pump and an HP pump. Fuel from the tanks is initially supplied to the LP pump. From the LP fuel pump fuel is supplied to the Fuel Oil Heat Exchanger (FOHE) for fuel heating and oil cooling. Then the fuel goes through the LP fuel filter. HIGH PRESSURE FUEL The filtered LP fuel is returned to the high-pressure (HP) fuel pump. The HP fuel pump pressurizes the fuel and supplies the Fuel Metering Unit (FMU), the Variable Stator Vane (VSV) actuators and the Air Oil Heat Exchanger (AOHX) modulating valve. The FMU, which contains servo valves, is mounted below the fuel pump assembly. A metering valve in the FMU adjusts the fuel flow delivered to the combustion chamber. This fuel flow, from the FMU, successively goes through the fuel flow transmitter and the HP fuel filter before supplying the fuel manifolds and Fuel Spray Nozzles A Pressure Raising and Shut-Off Valve (PRSOV), installed inside the FMU downstream of the metering valve, starts or stops the fuel flow and keeps the fuel at a satisfactory pressure. An overspeed valve in the FMU can close the PRSOV in case of N1, N2 or LP turbine overspeed. CONTROL Before engine start, the MASTER switch is OFF, the LP valve and the PRSOV are closed. When the MASTER switch is set to ON, the LP valve opens and the EEC controls the PRSOV to open by. The EEC controls the fuel flow through the metering valve in response to the throttle control lever demand or to the auto thrust system command. Engine normal shut down is done by setting the MASTER switch on OFF which closes the LP valve and the PRSOV directly. The EEC can also close the PRSOV automatically in case of automatic start abort on ground. MONITORING For fuel system monitoring and ECAM indication, the EEC uses the following sensors:- the fuel flow transmitter for fuel flow and fuel used indications,- the LP fuel filter differential pressure switch for filter clogging indication,- the fuel low pressure switch for fuel pressure monitoring. To monitor the metering valve and the PRSOV positions, the EEC uses sensors inside the FMU.