Engine Start and Trim (Synchronization) Panels Dornier 328Jet - Fuel Control System Dornier 328Jet - Fuel Control System

Dornier 328Jet - Fuel Control System

FADEC System Schematic (one engine shown) Dornier 328Jet - Fuel Control System

Fuel Components Inboard Dornier 328Jet - Fuel Control System

FUEL CONTROL SYSTEM

General The engine fuel system provides the engine with fuel at the required pressure and flow to permit control of engine thrust, operates the variable guide vane actuator and provides the motive flow required by the aircraft fuel feed system. The engine fuel system is controlled by the thrust lever, a dual Full–Authority Digital Electronic Control (FADEC) and the Hydro Mechanical Unit (HMU). A Permanent Magnet Alternator (PMA), driven by the accessory gearbox, supplies power to the Engine Electronic Control (EEC) – part of the FADEC – and the overspeed protection circuit. During engine start/shut down or as a back up the EEC is powered by the aircraft electrical system. With the engines running the EEC is independent of the aircraft electrical system.

Engine Control System The engine fuel control system regulates the fuel flow and operates the engine variable guide vane system as a function of various schedules to meet the flight crew demands. The system components control the following:

– proper fuel flow at minimum fuel introduction speed (5.2% N2) – sequence of fuel distribution to the appropriate fuel nozzles during engine start – control of ground idle speed – to provide surge free acceleration – to provide rapid deceleration without extinguishing the combustion – to provide fuel shut off and fuel dump after shut down – to provide protection against ITT overtemperature – to provide protection against High Pressure (HP) and Low Pressure (LP) compressor (fan) overspeed

The engine fuel control system is supplied with fuel from the aircraft fuel system.

Fuel feed to the engine is provided by jet booster pumps located in the wing feeder tank. The motive fuel flow, to drive the jet booster pumps, is supplied by the engine mounted fuel pump. Should the jet booster pumps fail, the supply of fuel to the engine can be maintained by the electrical booster pump which is also located in the wing feeder tank.

To prevent fuel accumulation in the combustion section following an engine shutdown, a fuel dump valve will purge remaining fuel from both the primary and secondary fuel manifolds into a fuel ”waste” tank, located on the outer bypass duct. Via an ejector pump purged fuel will be recycled to the LP fuel supply line.

A mechanical fuel shut–off valve, mounted on the dump valve, provides an automatic engine shut down in the event of a separation of the low pressure compressor (fan) from the low pressure turbines. Dornier 328Jet - Fuel Control System

Full Authority Digital Electronic Control (FADEC) Engine thrust is controlled by a dual channel Full Authority Digital Electronic Control (FADEC) which regulates HP compressor speed (N2) and LP compressor (fan) speed (N1) in response to a flight crew–operated Thrust Lever Angle (TLA), ambient conditions, aircraft discrete inputs and engine operating limits. The thrust lever settings are: CUT–OFF, IDLE, MAX CRUISE, MAX CLIMB and TAKE–OFF. The main components of the engine control system are the Thrust Lever (TL), EEC and the HMU. The HMU responds to the electrical commands from the EEC to provide precise engine control, optimize engine performance and improve specific fuel consumption. During the engine start–up phase and when the engine is operating at idle speed, the EEC supervises and controls the HP compressor speed (N2). When the engine is operating above idle speed, the EEC controls and supervises the LP compressor (fan) speed (N1). The EEC controls and supervises the respective compressors in accordance with the data supplied by aircraft and engine sensors, engine trim and discrete inputs from the flight compartment.

The appropriate N1 speed to achieve the required thrust is determined by the EEC. The N1 speed is a function of TLA and the ambient conditions. The EEC adjusts the fuel metering valve position within the HMU, to achieve the appropriate N1 speed to produce required thrust.

The calculated N1 speed is a function of:

– TLA. – Ambient conditions: Engine – total inlet temperature, – inlet total pressure, – inlet pressure. – Discrete inputs from systems or conditions such as cabin bleed(s) open and nacelle anti–ice. – Specific engine trim (T4.5 and N1). – Mechanical red line speeds. – Engine thermal protection.