What component controls fuel flow and pressure in response to FADEC signals?

The component that controls fuel flow and pressure in response to FADEC (Full Authority Digital Engine Control) signals is the Fuel Pump Metering Unit. This unit is a critical part of the fuel system in modern aircraft engines, acting as the interface that regulates how much fuel is delivered to the engine based on the operational requirements dictated by the FADEC.

When the FADEC sends signals reflecting the needs of the engine—such as during different phases of flight, including takeoff, cruise, or landing—the Fuel Pump Metering Unit adjusts the fuel flow accordingly. This precise control is essential for maintaining the optimal fuel-air mixture for combustion, ensuring efficient engine performance, proper thrust generation, and reduced emissions.

In contrast, while components like the Fuel Injector System and Air Fuel Ratio Controller play important roles in the delivery and coordination of fuel and air, they do not directly control the fuel flow and pressure in a response-driven manner as dictated by FADEC. The Fuel Injector System is responsible for atomizing the fuel for better combustion, and the Air Fuel Ratio Controller adjusts the mixture but relies on the Fuel Pump Metering Unit to supply the correct amount of fuel. The Pressure Relief Valve serves to protect the system from excessive pressure but is not involved in the control of fuel flow