What are the main components of the fuel metering system?

The fuel metering system of the typical gas turbine engine consists of an engine-driven pump, fuel flow transmitter, fuel control with an electronic engine control, a distribution system or manifold, flow divider, and fuel discharge nozzles.

What are the three types of fuel controls?

Gas turbine engine fuel controls can be divided into three basic groups:

  • Hydromechanical.
  • Hydromechanical/electronic.
  • Full Authority Digital Engine (or Electronics) Control (FADEC)

What are the two valves inside the HMU for fuel distribution and there function?

An HMU contains the fuel metering section with fuel metering valve and high pressure shut-off valve as well as the electrohy- draulic servo valves for the control of the fuel pressures to the actuators in- stalled outside the HMU on the engine.

How does fuel injection system work?

A modern fuel injection system works by atomising the fuel at high pressure, mixing it with clean air as it passes the inlet manifold, before entering the combustion chamber of each cylinder. The key element of the electronic modern fuel injection system is the word “electronic.”

How does a fuel metering valve work?

To adapt the fuel pressure in the rail, the fuel metering valve on the mechanical fuel pump controls the amount of fuel entering the pump. The plunger is held fully open by a spring to let fuel pass through.

What is the difference between gravity feed and pressure feed fuel system?

The pump feed system is opposite to a gravity feed system in that the pump is able to provide sufficient pressure to not only move fuel to an engine that is higher than the tank, but to do so with the pressure required for a fuel-injection system.

What is the fuel flow requirement for a gravity feed system?

The fuel flow rate for gravity systems (main and reserve supply) must be 150 percent of the takeoff fuel consumption of the engine.

What controls the fuel metering unit?

What controls fuel flow?

Fuel flows through a small metal fuel line from the tank to the engine. The flow of fuel to the engine is controlled by a fuel valve located on the fuel line.

Which controls the power supply to the APU EEC unit?

Power for the EEC comes from the aircraft electrical system or the permanent magnet alternator (PMA). When the engine is running, the PMA supplies power to the EEC directly. The EEC is a two channel computer that controls every aspect of engine operation.

What is the purpose of the flyweight governor in the HMU?

A fly weight governor is used to control the position of throttle valve. The flyweights are driven by the engine speed proportional to engine RPM, and the compression of the speeder spring is controlled by the pilot throttle lever.