No light-off within how many seconds of fuel commanded ON will abort the start?

• A. 5 seconds
• B. 10 seconds
• C. 13 seconds
• D. 20 seconds

Answer: (C)

During a PC-12 NGX start, once fuel is commanded ON, the combustor must ignite within a short, defined time window. This light-off within about thirteen seconds is critical because running the start with fuel flowing but ignition not present can lead to fuel-rich buildup, potential flooding, and overheating of the starter or turbine components. If light-off does not occur within that window, the start should be aborted to protect the engine and system. If light-off happens within the window, you proceed with the start and monitor the engine as it accelerates toward a stable idle; if not, follow the abort procedure and prepare for a retry after the prescribed cooldown.