What is the normal APU RPM range?

The normal APU RPM range is critical for ensuring the efficient performance of the Auxiliary Power Unit in the C-130J. The range from 98% to 105% represents the optimal operational conditions for the APU, allowing it to generate the necessary power for supporting aircraft systems while maintaining stability and reliability. Operating within this range ensures that the APU functions effectively without over-revving, which could lead to increased wear or potential failure.

This range is designed to provide a buffer for any operational fluctuations while ensuring the performance characteristics are met. When the RPM remains within this specified percentage, it contributes to the APU's overall lifespan and operational safety, allowing it to deliver consistent electrical and pneumatic power for ground operations.

The other ranges listed do not meet the manufacturer's specified conditions for normal operation, as they fall outside the recommended RPM parameters that ensure efficient and safe performance of the APU.