What is the APU operating range maximum RPM in percent?

What is the APU operating range maximum RPM in percent?

• A. 104%
• B. 106%
• C. 108%
• D. 110%

Answer: (B)

APU RPM is measured as a percent of its rated speed, and the upper limit allowed for normal operation is 106 percent. This gives a small margin for transient fluctuations during start, load changes, or bleed-air requests while keeping the APU safely within its mechanical and thermal limits. If the speed climbs beyond that, protective logic will prevent further increase or shut the APU down to avoid overspeed damage. Therefore, 106% is the correct maximum operating range RPM.

APU RPM is measured as a percent of its rated speed, and the upper limit allowed for normal operation is 106 percent. This gives a small margin for transient fluctuations during start, load changes, or bleed-air requests while keeping the APU safely within its mechanical and thermal limits. If the speed climbs beyond that, protective logic will prevent further increase or shut the APU down to avoid overspeed damage. Therefore, 106% is the correct maximum operating range RPM.