FAA Aviation Mechanic Powerplant (AMP)Turbine EnginesMedium
A technician monitors a turbine engine start and observes that the starter disengages, EGT stays within normal limits, but N1 stabilizes well below idle speed and the engine will not accelerate further without shutting down. This is an example of a:
- AHung start
- BHot start
- COverspeed
- DCompressor stall
Show answer & explanationAnswer & explanation
Correct answer: A. Hung start
A hung (false) start occurs when the engine lights off and accelerates partially but stalls at a low RPM below idle, usually due to insufficient starter assist, low bleed air pressure, or fuel scheduling issues, without exceeding EGT limits.
Why the other options are wrong
- B. A hot start involves EGT exceeding limits, which is not present here.
- C. An overspeed involves RPM exceeding limits, the opposite of this scenario.
- D. Compressor stall produces banging/vibration and typically occurs at higher power settings.
Hung Start
A start condition in which the engine partially accelerates but stabilizes below idle RPM and fails to reach self-sustaining speed, typically without exceeding EGT limits.
- Often caused by insufficient starter torque or bleed air
- EGT remains within limits, unlike a hot start
- Requires shutdown and troubleshooting before re-attempting start
Memory trick: Hung start = engine gets 'hung up' below idle, stuck and stalled.