What is the maximum permissible minimum engine run-up power setting?

The maximum permissible minimum engine run-up power setting for the CRJ 900 is 90% N1. This figure is critical for ensuring the engine operates within safe limits during pre-flight engine checks. At this setting, the engines are subjected to a controlled power level that allows for sufficient system checks, such as assessing engine performance, engine responsiveness, and verifying that all systems function correctly without putting undue stress on the engine components.

Maintaining the run-up at 90% N1 allows pilots to identify any potential issues while still ensuring the integrity of the engines is preserved. Exceeding this power setting could lead to unnecessary wear on engine components or even operational hazards. Therefore, adhering to this limitation not only aligns with best practices for flight safety but also enhances the longevity and reliability of the engines throughout their service life.