Does an EGT reading of 716-824°C during APU start indicate a malfunction?

An EGT (Exhaust Gas Temperature) reading during APU start that falls within the range of 716-824°C is considered abnormal and indicates a potential malfunction.

Typically, during the starting sequence of an auxiliary power unit, certain EGT thresholds are established to ensure that the engine is operating within safe limits. If the EGT exceeds the upper threshold, it may suggest that there is an over-temperature condition, which can be caused by various issues such as fuel-air mixture problems, ignition system anomalies, or compressor stalls. Monitoring EGT is crucial because prolonged exposure to temperatures above the specified limits can lead to damage to engine components or even failure.

In contrast, a normal EGT reading during start-up would fall within a defined acceptable range, usually below the critical thresholds. Understanding these temperature parameters is essential for those working with the APU, as it helps in identifying and addressing potential operational issues early on.