Under which condition would both igniters activate?

Under which condition would both igniters activate?

• A. Normal start
• B. AIR START
• C. APU start
• D. Idle

Answer: (B)

Ignition reliability during starting is the focus here. Turbine engines use two igniters (redundant spark plugs) so they can ensure a confident light-off. When you perform an air start, bleed air or external air drives the starter and the airflow can be unstable, which makes reliable ignition less certain. Activating both igniters in this mode increases the chance that the fuel-air mixture will ignite promptly and the engine will continue to spool up smoothly. In a normal start, one igniter may suffice initially to minimize wear and heat, while idle is a non-start condition, so ignition isn’t being commanded. An APU start uses the APU to spin the engine, but it doesn’t inherently require both igniters to fire unless the system específico dictates it; the air start scenario is the one that routinely calls for both igniters.

Ignition reliability during starting is the focus here. Turbine engines use two igniters (redundant spark plugs) so they can ensure a confident light-off. When you perform an air start, bleed air or external air drives the starter and the airflow can be unstable, which makes reliable ignition less certain. Activating both igniters in this mode increases the chance that the fuel-air mixture will ignite promptly and the engine will continue to spool up smoothly.

In a normal start, one igniter may suffice initially to minimize wear and heat, while idle is a non-start condition, so ignition isn’t being commanded. An APU start uses the APU to spin the engine, but it doesn’t inherently require both igniters to fire unless the system específico dictates it; the air start scenario is the one that routinely calls for both igniters.