On the ground, what is the correct crank cycle for starting engines 1 and 2?

• A. 90 seconds on, 10 seconds off
• B. 120 seconds on, 10 seconds off
• C. 60 seconds on, 5 minutes off
• D. 30 seconds on, 5 minutes off

Answer: (A)

The concept being tested is how to protect the starter and electrical system during engine start by following a duty cycle. On the ground, starting engines 1 and 2 uses a limited crank time to avoid overheating the starter motor and draining the battery. The 90 seconds on with a 10-second off cooling interval is the standard pattern because it gives enough continuous cranking to attempt ignition while staying within thermal limits, with a brief rest to prevent overheating before the next attempt or moving to the other engine. Longer continuous cranking, like 120 seconds, risks damaging the starter; shorter cycles such as 60 seconds on with a long off would waste time and may not reliably start the engine, and 30 seconds on with an extended off time is usually insufficient to achieve a successful start.