What is the APU starter cutout RPM?

• A. 46%-60%
• B. 40%-50%
• C. 60%-70%
• D. 70%-80%

Answer: (A)

The main idea is when the APU transitions from starter-assisted to self-sustained operation. The starter cutout RPM is the speed at which the starter disengages and the APU can run on its own. In typical practice, this occurs at about half of the APU’s normal spool speed, with a small tolerance that can vary by aircraft. So the correct choice reflects that mid-speed range rather than a very low or very high RPM. If the speed is too low, the APU may not light off reliably; if it’s too high, the starter could stay engaged longer than needed or risk overspeed once the APU is running.