FAA Powerplant Written Practice Test

Why is the capacitor-type ignition system widely used on turbine engines?

1. It is cost-effective and simple

2. It produces a high voltage and intense spark

3. It is less prone to mechanical failure

4. It uses low-intensity sparks

The correct answer is: It produces a high voltage and intense spark

The capacitor-type ignition system is widely employed on turbine engines primarily because it generates a high voltage and produces an intense spark. The high voltage is crucial for igniting the fuel-air mixture in the combustion chamber, especially in environments with a high flow rate and significant airflow, where ignition might otherwise be challenging. An intense spark ensures that ignition is reliable and consistent, which is vital for maintaining the performance and efficiency of turbine engines. In turbine engines, the combustion process requires quick and effective ignition to support the rapid operational demands. The intensity of the spark provided by the capacitor-type ignition system ensures that even if there are variations in fuel quality or environmental conditions, the ignition process remains robust and efficient. While other factors like cost-effectiveness, simplicity, and mechanical reliability can contribute to an ignition system's overall desirability, the dominant reason for the prevalence of capacitor-type systems in turbine engines is the ability to produce a strong and effective ignition source, which is critical for optimal engine performance.