Which of the following is included in the APU pre-flight check procedure?

The correct answer highlights a critical aspect of the APU pre-flight check procedure, which is to inspect APU fuel levels and check operational switches. This step is essential to ensure that the APU has adequate fuel available to operate during flight and that all necessary switches are set correctly for safe operation. Proper fuel levels are crucial for the APU to function efficiently, providing electrical power and bleed air to the aircraft systems while on the ground.

Additionally, checking operational switches ensures that the APU can activate and function as intended without any issues, which is vital for the reliability of the aircraft's performance. This systematic approach helps to prevent potential malfunctions during flight and supports overall mission readiness.

The other choices, while related to aircraft operations, do not fit specifically within the APU pre-flight check. Ensuring the APU is fully refueled does not capture the practice of assessing actual fuel levels in a functional context, and verifying the aircraft is in maintenance mode pertains more to the overall operational state of the aircraft rather than the APU specifically. Testing the thrust vectoring system does not relate to the APU, as this component is concerned with propulsion and maneuverability rather than auxiliary power functions. Therefore, option B is the most relevant and accurate choice for