Can the APU be operated without the access panel installed?

The correct answer indicates that while the APU can be operated without the access panel installed, specific precautions must be taken. Operating the APU in this condition can pose safety risks, such as the potential for debris to enter the APU or the risk of exposure to hot surfaces and moving parts. Therefore, ensuring that safety measures and protocols are followed is critical when the access panel is removed. This approach balances the operational flexibility of using the APU while addressing safety concerns, recognizing that certain risks are mitigated through careful planning and precautions.