What should you do if the APU fuel shutoff valve is not operating properly?

When the APU fuel shutoff valve is not operating properly, it is essential to prioritize safety and the proper functioning of the aircraft systems. The fuel shutoff valve plays a critical role in controlling fuel flow to the APU. If this valve is not operating correctly, it could lead to unsafe operating conditions, such as fuel leaks or uncontrolled fuel flow, which can result in potential fire hazards or damage to the APU.

By not operating the APU under such circumstances, you minimize the risk of complications that could arise from an improperly functioning fuel system. This precaution helps ensure that the aircraft remains safe and operational. Addressing the issue before the APU is used again is crucial in maintaining the safety and reliability of aircraft operations.