Propulsion System Operation
What this domain tests
This domain covers thrust management in normal operations, reverse thrust, and handling limitations that protect the engine and airframe.
Core rules
- Thrust is set by thrust lever position, which commands N1 or EPR through the FADEC or EEC. Takeoff thrust is time-limited; climb and cruise use lower ratings.
- Reverse thrust: cascade or target and bucket types. It is used on the ground after touchdown to reduce stopping distance; selection below a set speed is usually inhibited or discouraged to avoid re-ingestion and FOD.
- Handling limits: avoid rapid throttle movements that cause surge or EGT overshoot; respect idle times before shutdown; do not use reverse in flight unless certified.
- Cross-bleed and bleed air use affect thrust; engine anti-ice must be on when icing conditions exist.
Worked example
After touchdown at 120 kt, the pilot selects reverse thrust; at 60 kt the reversers are stowed. Reasoning: reverse is effective at high speed but at low speed it can throw debris into the engine and disturb directional control. The speed calls come from the aircraft flight manual, not from a generic rule.
Traps
- Using reverse thrust in flight on an aircraft not certified for it.
- Slamming the thrust levers forward; the FADEC may schedule fuel, but surge margin can still be lost.
- Forgetting that bleed air extraction reduces thrust and increases EGT.
- Assuming reverse thrust is symmetrical in a crosswind; it may not be.
Key points
- Thrust lever commands N1 or EPR through the FADEC or EEC.
- Reverse thrust is for ground use; stow at low speed.
- Avoid rapid throttle movements; respect surge margin and EGT limits.
- Bleed air and anti-ice reduce thrust.
- Use the AFM for reverse and handling limits.