How long is the cooling time required after the second start sequence?

The cooling time required after the second start sequence is 60 seconds OFF. This duration is crucial to ensure the engine's components adequately cool down and prevent potential heat-related damage. After an engine start, especially in a second sequence, the internal temperatures rise significantly due to the combustion process. Allowing a specified period for cooling helps maintain the integrity of the engine and other related systems by ensuring components do not overheat. Therefore, 60 seconds is established as a safety standard in operational procedures, providing a balance between efficiency and the maintenance of aircraft safety and reliability. The other options presented, while they may suggest longer cooling times, do not reflect the prescribed operational guidance for this specific scenario.