FAA Powerplant Written Practice Test

Why are turbine engine igniters typically resistant to carbon fouling?

1. They use low voltage

2. They produce lower intensity sparks

3. The spark cleans the igniter

4. They are made of special materials

The correct answer is: The spark cleans the igniter

Turbine engine igniters are designed to resist carbon fouling primarily because the spark they produce can effectively clean the igniter itself. During igniter operation, particularly at the moment of ignition, the high temperature of the spark can burn off any carbon deposits that may have accumulated on its surface. This self-cleaning mechanism is crucial in maintaining the performance and reliability of the igniter over time, ensuring that it continues to function correctly without becoming obstructed by carbon buildup. In the context of turbine engines, where combustion occurs at higher temperatures and pressures compared to reciprocating engines, the prevention of carbon fouling is especially important because it can lead to ignition failures. The ability of the igniter to generate a high-energy spark not only initiates combustion but also acts to mitigate the likelihood of carbon fouling by continuously maintaining a clean surface.