What can a consistent high exhaust temperature signal?

A consistent high exhaust temperature is a significant indicator of potential combustion problems within the Auxiliary Power Unit (APU). This abnormal condition suggests that the combustion process may be inefficient, leading to incomplete burning of fuel. When the exhaust temperature rises above the normal operational range, it can signal that the APU is encountering issues such as improper fuel-air mixture, excessive fuel flow, or a malfunctioning component affecting combustion.

Monitoring exhaust temperature is crucial because sustained high temperatures can lead to further damage in the APU, degrade performance, and ultimately compromise the safety and efficiency of aircraft operations. Therefore, identifying and addressing high exhaust temperatures promptly can help prevent more serious maintenance issues and ensure the APU operates efficiently within its design parameters.