When N2 increases to greater than ___ percent, the FADEC no longer monitors start parameters.

When N2, which refers to the high-pressure compressor speed in the engine, increases beyond 55 percent, the Full Authority Digital Engine Control (FADEC) system will no longer monitor the start parameters. This is a critical threshold because at this level of N2, the engine has reached a sufficient level of stability and performance.

Monitoring start parameters is crucial during the initial phases of engine start-up to ensure that all conditions are within safe operating limits. Once the N2 surpasses the 55 percent threshold, the engine is considered to be self-sustaining at that rate, and the FADEC can shift its focus to maintaining optimal performance instead of continuously monitoring the start conditions.

This transition reflects the inherent design of modern engine control systems, which prioritize safe operation during critical phases and adjust their monitoring functions as conditions stabilize. The choice of 55 percent is based on performance metrics established during the engine development and certification process to ensure reliability and safety throughout the engine's operational envelope.