With which type of turbine-engine ignition system is a glow plug igniter used?

• A. High-voltage system
• B. Low-voltage system
• C. Capacitive discharge system
• D. Continuous-discharge system

Answer: (B)

The main idea is hot-surface ignition: a glow plug heats up to ignite the fuel–air mixture during start. In turbine-engine ignition, there are several ways to produce ignition, and glow plugs are used specifically with a low-voltage ignition approach. The glow plug acts as a resistive heater inside the combustion chamber, turning electrical energy into heat that preheats or sustains ignition, which is especially important when ambient temperatures are low or during cold starts. This makes ignition reliable when the system isn’t relying on a high-energy spark to jump the gap.

Other ignition methods rely on electrical sparks produced by high-energy sources, such as spark-based capacitive or continuous-discharge systems, which do not use a glow plug heating element. Those systems ignite via a spark rather than by a hot surface, so a glow plug isn’t part of their normal operation.