FAA Powerplant Written Practice Test

What type of ignition system is primarily used in most turbine aircraft engines?

1. Magneto ignition

2. Capacitor discharge

3. Inductive ignition

4. Battery-powered ignition

The correct answer is: Capacitor discharge

Most turbine aircraft engines utilize a capacitor discharge ignition (CDI) system due to its advantages in reliability, performance, and efficiency. CDI systems work by storing charge in a capacitor, which is released as a high-voltage pulse to ignite the fuel-air mixture in the combustion chamber. This method provides a more consistent spark and is less affected by factors such as temperature and altitude, which makes it highly suitable for turbine engines that operate in varied conditions. In contrast, magneto ignition systems are more commonly used in piston engines. They rely on mechanical components to generate electrical power, which can be less efficient and reliable in turbine engines that demand greater performance. Inductive ignition systems are also not the standard in turbine engines, as they typically work with lower energy levels and may not provide the necessary spark energy for efficient turbine operation. Battery-powered ignition systems can be used but are generally reserved for specific applications where CDI is not feasible. Overall, the reliance on CDI systems in turbine engines reflects the need for high performance and reliability, aligning with the operational requirements of turbine-powered aircraft.