What is the function of the fuel shutoff valve in the APU system?

The function of the fuel shutoff valve in the APU (Auxiliary Power Unit) system is to enable or disable fuel supply to the APU. This is crucial for managing the operation of the APU, as it ensures that fuel is only supplied when the APU is needed for starting or providing power. When the APU is not in use or during certain maintenance procedures, the fuel shutoff valve can be closed, effectively cutting off the fuel supply. This feature helps prevent fuel leaks, enhances safety by ensuring that fuel is not unintentionally delivered to the APU when it is not operating, and allows for controlled management of the APU's fuel system.

While controlling fuel flow to the main engines, regulating the fuel mixture, and disconnecting fuel during maintenance are important functions within the overall fuel system of the aircraft, the specific role of the fuel shutoff valve is primarily focused on managing the fuel supply to the APU itself.