What is the primary purpose of the ignition system in starting and relighting the combustor?

• A. To regulate fuel flow.
• B. To lubricate ignition components.
• C. To provide a reliable high-energy spark to ignite the fuel-air mixture and re-light after flameout.
• D. To measure combustor temperature.

Answer: (C)

The ignition system’s primary role during starting and relighting is to deliver a reliable high-energy spark to ignite the fuel-air mixture and re-light the combustor after flameout. A strong, timely spark is essential to start combustion quickly and reliably under varying conditions (cold starts, lean mixtures, or after a flameout), ensuring the engine can continue to operate. The other functions listed aren’t the main job of the ignition system: regulating fuel flow is handled by the fuel control, lubrication of ignition components is a maintenance/through-life concern, and measuring combustor temperature is done by sensors for monitoring and control.