During engine start, move the thrust lever to IDLE when N2 reaches what percent?

During engine start, move the thrust lever to IDLE when N2 reaches what percent?

• A. 20-25%
• B. 0%
• C. 8-10%
• D. 40-50%

Answer: (C)

Timing the throttle transition during start is tied to the turbine’s core speed, shown by N2. As the starter brings the engine up and ignition light-off begins, you move the thrust lever to IDLE when N2 reaches about 8–10%. At that point the core is spinning safely enough to sustain idle fuel flow, and the engine can settle into a stable idle without over-fueling or applying excess demand. If you waited for a higher N2, the engine would already be on its way away from idle once you set it, and if you moved too early, the core wouldn’t be light-off yet and could flame out. This 8–10% N2 cue ensures a smooth, controlled transition from start to stable idle on the Beechjet 400A.

Timing the throttle transition during start is tied to the turbine’s core speed, shown by N2. As the starter brings the engine up and ignition light-off begins, you move the thrust lever to IDLE when N2 reaches about 8–10%. At that point the core is spinning safely enough to sustain idle fuel flow, and the engine can settle into a stable idle without over-fueling or applying excess demand. If you waited for a higher N2, the engine would already be on its way away from idle once you set it, and if you moved too early, the core wouldn’t be light-off yet and could flame out. This 8–10% N2 cue ensures a smooth, controlled transition from start to stable idle on the Beechjet 400A.