At what distance must you wear a cranial when the APU is turned on?

Wearing a cranial when the Auxiliary Power Unit (APU) is operational is crucial for safety due to the potential for hearing damage and the risk of head injuries from debris. The correct distance at which a cranial should be worn is 50 feet. This guideline is established based on the noise levels generated by the APU, which can reach dangerous levels in close proximity.

At this distance, wearing the cranial offers adequate protection against the noise and any hazards associated with the APU's operation. The other distances are outside of the established safety protocols, which have been designed to minimize risk effectively. Understanding these safety distances and the rationale behind them is essential for ensuring the safety of personnel working around operational equipment.