APU Starter Limitation

Question 1

Continuous operation of the APU starter when powered by the airplane batteries:

Answer 1

3 consecutive starts - 30 seconds per Start
20 Minutes for starter cool down
1 hour cool down before next full starter cycle

Question 2

Continuous operation of the APU starter when powered by an external DC power source:

Answer 2

2 consecutive starts - 15 seconds per start
20 Minutes for starter cool down
2 additional start attempts may be made
1 hour cool down before next full starter cycle

Question 3

Successful consecutive starts

Answer 3

limited to 6 at 10 minute intervals per start