Which sequence correctly reflects the requirement for APU starter attempts and OFF times?

Which sequence correctly reflects the requirement for APU starter attempts and OFF times?

• A. Attempt 1 and 2 require 60 sec OFF; Attempt 3 requires 5 min OFF.
• B. Attempt 1 and 2 require 30 sec OFF; Attempt 3 requires 2 min OFF.
• C. All attempts require 1 min OFF.
• D. There are no OFF time requirements between attempts.

Answer: (A)

APU starter limits are all about giving the starter and the APU time to cool after each start attempt. The pattern here uses a 60-second OFF interval between the first and second attempts, and also a 60-second OFF interval between the second and third attempts. After the third attempt, a longer five-minute OFF period is required before any further attempts. This longer cooldown after multiple starts protects the starter from overheating and ensures the APU has time to stabilize. Other options don’t fit because they call for either the same short cooldown for all attempts, no cooldown, or an incorrect longer cooldown timing.

APU starter limits are all about giving the starter and the APU time to cool after each start attempt. The pattern here uses a 60-second OFF interval between the first and second attempts, and also a 60-second OFF interval between the second and third attempts. After the third attempt, a longer five-minute OFF period is required before any further attempts. This longer cooldown after multiple starts protects the starter from overheating and ensures the APU has time to stabilize. Other options don’t fit because they call for either the same short cooldown for all attempts, no cooldown, or an incorrect longer cooldown timing.