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When the starter may release a turbine engine

Aviation Mechanic Powerplant (AMP) practice question 3 of 11 on Ignition and Starting Systems. ACS element AM.III.H.K7 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic Powerplant (AMP) practice mode.

Question bank updated 2026-09-22

QUESTIONDuring a gas turbine engine start, at what point may the starter stop assisting the engine?

  1. AAs soon as light-off is shown by the EGT
  2. BOnce the ignition system is switched on
  3. CWell above self-accelerating speed
Show the answer and explanation

Correct answer: C. Well above self-accelerating speed

  • A — incorrect Light-off comes early in the sequence, long before the engine can sustain its own acceleration, so the starter must keep cranking.
  • B — incorrect Ignition is turned on as soon as the starter has established airflow, which is near the beginning of the cycle, not the end.
  • C — correct The starter must continue to assist considerably above the self-accelerating speed; cutting out earlier delays the start or lets the engine decelerate.

BACKGROUND

A gas turbine engine is started by rotating the high-pressure compressor fast enough to pass the air needed to support combustion. Once the starter has established airflow, ignition is turned on, then fuel, and light-off occurs. At low cranking speeds the fuel flow rate is not enough for the engine to accelerate on its own, so the starter keeps cranking past self-accelerating speed. If starter assistance stopped below that speed, the engine would fail to reach idle or might even decelerate, and stopping too near that speed risks a hot start, a hung start, or both.

STUDY TIP

Learn the sequence as starter, airflow, ignition, fuel, light-off, then starter cutout well above self-accelerating speed; the starter and the ignition are both cut off automatically at the proper points.

KEY POINTS

  • The starter assists considerably above self-accelerating speed.
  • Cutting out too early causes a hung start, a hot start, or a failure to accelerate.
  • Airflow must exist before the air-fuel mixture is ignited.

SOURCES

  • sources/amp-powerplant/ch05.txt "Gas Turbine Engine Starters"
Practice the Aviation Mechanic Powerplant (AMP) test →Timed 100-question exam, by ACS area, or review your misses. Free.
MORE ON IGNITION AND STARTING SYSTEMS

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-32B Aviation Maintenance Technician Handbook – Powerplant, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.