Does the exhaust from an APU pose a personnel hazard during start and operation?

The assertion that the exhaust from an Auxiliary Power Unit (APU) does not pose a personnel hazard during start and operation is based on design and operational considerations aimed at ensuring safety.

When an APU is operating, particularly during start, it does produce exhaust emissions; however, these emissions are typically directed away from personnel areas through well-designed exhaust systems. The placement of the APU is carefully considered in aircraft design to minimize the risk of harmful exposure to the exhaust, which includes noxious fumes and heat.

Additionally, strict operational procedures are in place regarding personnel access during APU operation. Ground crews are trained to maintain a safe distance during start and operation, and warning systems may be employed to alert personnel to the APU's operational status. These practices further mitigate potential hazards.

In conclusion, while there are always inherent risks when working with aircraft systems, the specific design of the APU exhaust system, paired with established safety protocols, significantly reduces any potential hazard to personnel.