What are the starter cranking limits on the ground for Iterations 1 and 2?

The starter cranking limits on the ground for Iterations 1 and 2 are established to ensure the safe and effective operation of the aircraft’s starting system. A limit of 90 seconds on with a 10-second rest period allows for sufficient cranking time to start the engine while minimizing the risk of overheating the starter motor. This precaution is critical in preventing potential damage to the starter, which can occur due to prolonged operation without adequate cooling.

Additionally, the 10-second off interval provides a brief cooldown period, which is essential for the components to recover before another start attempt. This cycle is particularly important in a multi-engine plane, where managing the health of the starters directly affects overall performance and safety.

In comparison, other options either extend the continuous cranking time or reduce the cooldown period, which goes against the guidelines for maintaining the starters' integrity and functionality. Thus, the specified limits of 90 seconds on and 10 seconds off align with operational safety standards for aircraft systems.