Why is it necessary to monitor APU exhaust temperatures?

Monitoring APU exhaust temperatures is crucial primarily to prevent overheating and potential engine failure. The APU operates under varying loads, and excessive exhaust temperatures can indicate that the unit is not functioning within its designed parameters. Overheating can lead to damage not only to the APU itself but can also compromise the systems it supports. If exhaust temperatures rise beyond acceptable limits, this can lead to thermal stress and physical damage, ultimately jeopardizing the operation and reliability of the APU, and potentially leading to its failure. Therefore, keeping a close eye on these temperatures is vital for maintaining the APU’s health and ensuring overall aircraft safety and efficiency.