What is the ideal time to wait after the APU has reached operational temperature before starting the unit?

Waiting for the APU to reach operational temperature is crucial for ensuring optimal performance and longevity of the unit. The ideal wait time of 2 minutes allows the APU to stabilize its temperature after startup. During this period, the internal components reach their necessary operating temperatures, allowing for efficient combustion and reducing potential wear on the engine.

After starting, the temperatures within the APU need to equilibrate to ensure that all systems, such as oil pressure and electrical output, are functioning correctly. If the unit is engaged for power generation or other tasks too soon, it might not deliver the expected performance and could be susceptible to damage or malfunction due to thermal stress.

Additionally, this practice aligns with the recommendations provided in maintenance and operational guidelines, which emphasize the importance of allowing sufficient warm-up time to ensure reliability and effectiveness.