Which of the following is a common reason for a turbine to fail to relight after a flameout?

• A. Loss of ignition energy
• B. Excessive fuel supply
• C. Adequate air supply
• D. Igniters always work

Answer: (A)

Relighting a turbine after flameout depends on delivering enough ignition energy to ignite the fuel–air mixture in the combustor. If the ignition energy is lost—because an igniter fails, the power supply drops, or the ignition circuitry is compromised—the system can’t create a spark or hot surface to start combustion. Even with fuel present and air flowing, there’s nothing to ignite it, so the flame cannot be reignited. That’s why loss of ignition energy is the most common reason for a failed relight.

If the engine were flooded with fuel, or if the air supply were severely inadequate, relight could also fail, but those issues relate to mixture preparation rather than the fundamental need for an ignition source. And obviously, igniters do not always work; a failure of the ignition system is a common, practical cause of relight failure.