What is the APU's maximum start time from the start light to "ON SPEED" at 0°F and above?

The maximum start time from the start light to "ON SPEED" for the Auxiliary Power Unit (APU) at temperatures of 0°F and above is indeed 30 seconds. This timeframe is crucial for ensuring that the APU can efficiently and safely reach operational speed under optimal conditions.

During the APU start sequence, monitoring the time it takes to reach "ON SPEED" is essential for performance assessments and troubleshooting any potential issues. The designated 30 seconds is a standard benchmark, indicating that the APU should achieve its operational capacity within this time frame when environmental conditions are favorable.

This start time is significant as it contributes to the overall reliability and readiness of the APU, which powers essential systems and provides electrical and pneumatic capabilities to support the aircraft's operations. Understanding this parameter helps technicians and operators to assess the APU's health and readiness effectively.