The starter must not be used if the indicated N2 RPM exceeds what percentage?

The starter must not be used if the indicated N2 RPM exceeds what percentage?

• A. 45%
• B. 50%
• C. 60%
• D. 70%

Answer: (A)

During a turbine start, the starter is used to bring the engine up to a speed where ignition can take over and the engine can sustain operation. The indicated N2 speed serves as a safety threshold to decide whether to continue cranking. If N2 climbs past a small, predefined limit while the starter is on, it means the engine isn’t going to light off properly under those conditions, and continuing to crank can risk overspeed of the core, damage to the starter, or other abnormal conditions. Therefore, you should not use the starter once N2 exceeds 45 percent. If ignition isn’t established and N2 is already above that limit, you abort the start and troubleshoot before attempting again.

During a turbine start, the starter is used to bring the engine up to a speed where ignition can take over and the engine can sustain operation. The indicated N2 speed serves as a safety threshold to decide whether to continue cranking. If N2 climbs past a small, predefined limit while the starter is on, it means the engine isn’t going to light off properly under those conditions, and continuing to crank can risk overspeed of the core, damage to the starter, or other abnormal conditions. Therefore, you should not use the starter once N2 exceeds 45 percent. If ignition isn’t established and N2 is already above that limit, you abort the start and troubleshoot before attempting again.