What is the cooling time required after the first start sequence?

The correct cooling time required after the first start sequence is 60 seconds OFF. In aircraft operations, particularly with turbine engines, a cooling period is necessary after the engine start sequence to allow the engine components to stabilize and cool down before the next operation. This cooling time helps prevent excessive wear and thermal stress on the engine, which can occur from consecutive high-temperature operations without sufficient cooldown.

Understanding the cooling requirements is crucial in ensuring the longevity and performance of the aircraft's powerplant, aligning with maintenance and safety protocols in aviation. Thus, adhering to the 60 seconds OFF requirement is instrumental in promoting operational reliability and engine health.