Which of the following should occur to indicate that the engine is now self sustaining?

• A. When the engine accelerates without starter motor assistance
• B. When the starter motor remains energized after start
• C. When RPM drops and stabilizes
• D. When fuel flow stops unexpectedly

Answer: (A)

Self-sustaining operation means the engine can keep running on its own power after the starting system has done its job. The clearest sign is the engine accelerating and continuing to run without the starter motor providing drive. When you observe that it speeds up and maintains that speed without the starter, you know the engine is producing enough energy from its fuel and ignition to sustain operation.

If the starter motor remains energized after the start, the engine isn’t yet self-sustaining—the starter is still supplying the drive, indicating the engine hasn’t taken over completely. Merely RPM stabilizing isn’t a definitive signal of self-sustaining operation, since a stable speed can occur under various conditions and doesn’t guarantee the engine is no longer dependent on the starter. And fuel flow stopping unexpectedly would point to a fault or flameout risk, not to self-sustaining operation.