Which item is NOT part of the ignition system?

• A. Alternator
• B. FADEC
• C. Battery
• D. Two fan speed transmitters

Answer: (C)

Ignition in a modern turbine engine is powered and timed by the engine’s control and power system, not by starting batteries. The alternator supplies the electrical energy that runs the ignition circuit during normal operation, while FADEC acts as the control brain, deciding the exact moment to fire the igniters based on engine data. The two fan speed transmitters feed FADEC with spool speed information (such as N1) so it can schedule ignition appropriately. The battery, on the other hand, is mainly used to provide starting power and as a backup power source, not as a normal part of the ignition hardware or its control during steady flight. Therefore, the battery is not considered part of the ignition system.