During the PMU Autostart procedure, when will the ground start sequence terminate?

The ground start sequence during the PMU Autostart procedure is designed to ensure that the engine starts safely and efficiently. The correct answer is based on the timeline for light-off, which is the point at which combustion begins in the engine.

The ground start sequence will terminate if light-off does not occur within 10 seconds. This is critical to prevent the engine from attempting to start without the necessary combustion processes in place, which could lead to potential damage or inefficiency. A 10-second limit provides a clear and safe cutoff point for the start sequence, ensuring that pilots do not exceed this timeframe to avoid complications.

While it is true that light-off occurring within 5 seconds is a favorable outcome, it does not dictate the termination of the ground start sequence. Similarly, engine temperature exceeding 100 degrees Celsius or battery voltage falling below 24 volts are important metrics but do not trigger the termination of the sequence based on the specified timeline for light-off. Hence, the 10-second rule is a critical safety and operational parameter in the PMU Autostart procedure.