FAA Aviation Mechanic Powerplant (AMP)Ignition and Starting SystemsMedium
A turbine engine ignition exciter unit is being tested. What type of ignition system does this unit typically represent, and why is it required for turbine engines?
- AA capacitor discharge (high-energy) system, because turbine fuel requires a very hot, high-intensity spark for reliable ignition
- BA battery-only ignition system, because turbines do not require a magneto or exciter
- CA dual-magneto system identical to reciprocating engines but with larger coils
- DA low-tension magneto system, because turbine fuel requires a continuous low-voltage spark
Show answer & explanationAnswer & explanation
Correct answer: A. A capacitor discharge (high-energy) system, because turbine fuel requires a very hot, high-intensity spark for reliable ignition
Turbine engines use a capacitor discharge (CD) ignition system with a high-energy exciter unit because jet fuel is less volatile than aviation gasoline and requires a very hot, high-intensity spark to ensure reliable light-off, especially at altitude and low temperatures.
Why the other options are wrong
- B. Turbines require dedicated exciter units, not just battery power directly to plugs.
- C. Turbine ignition is fundamentally different from magneto-based reciprocating systems.
- D. Low-tension magnetos are used on some reciprocating engines, not turbines.
Turbine Ignition Exciter
A high-energy capacitor discharge unit that stores electrical energy and releases it in a very hot, intense spark across turbine igniter plugs for reliable ignition of jet fuel.
- Produces very high voltage, short-duration sparks
- Only 1-2 igniters needed per engine (unlike many spark plugs on recip engines)
- Required because jet fuel is less volatile than avgas
Memory trick: CD exciter = 'Capacitor Charges then blasts a Hot spark' for stubborn jet fuel