FAA Powerplant Written Practice Test

What is a benefit of the capacitor discharge ignition system in turbine engines?

1. Lower maintenance costs

2. Higher ignition reliability

3. Reduction of weight

4. Improved fuel efficiency

The correct answer is: Higher ignition reliability

The capacitor discharge ignition (CDI) system is designed to enhance the ignition process in turbine engines. One significant benefit of this system is its higher ignition reliability. In a CDI system, the capacitor rapidly discharges a high-voltage spark through the ignition plug, creating a more intense and consistent spark compared to traditional ignition systems. This potent spark is less susceptible to issues caused by unfavorable conditions such as high altitude, low temperature, or fuel quality variations, thus improving the overall reliability of the ignition process. Higher ignition reliability is particularly important in turbine engines, where consistent engine performance is critical for safety and efficiency. A reliable ignition system helps ensure that the engine starts properly and runs smoothly throughout its operation, reducing the risk of misfires or engine stalls. While the other options may suggest potential advantages, they do not capture the primary focus and function of a CDI system. For instance, although there may be some weight advantages or maintenance considerations, those are not the defining characteristics. Additionally, the CDI system does not primarily aim to improve fuel efficiency, although reliable ignition may indirectly support more efficient engine operation. Therefore, the higher ignition reliability stands out as the most crucial benefit associated with capacitor discharge ignition systems in turbine engines.