What could indicate an exceeding of NATOPS limits during engine start?

The indication of an exceeding of NATOPS limits during engine start is primarily associated with ITT, or Interstage Turbine Temperature. In the context of engine operation, especially during start-up, monitoring ITT is critical because it signifies how hot the engine is running. An ITT above 830 degrees Celsius indicates a situation where the engine is overheating, which could lead to damage or failure if not addressed promptly. This specific temperature threshold reflects operational limits that are established to ensure the safety and integrity of the engine.

While other factors such as low fuel pressure, battery failure, or ground power malfunction can certainly affect engine operation, they do not directly indicate an exceedance of NATOPS limits during the critical engine start phase. Low fuel pressure might affect engine performance but would not specifically signal that temperature limits have been surpassed. Similarly, battery or ground power issues would influence the ability to start the engine but are not indicators of overheating or exceeding safe operational temperatures. Therefore, monitoring ITT during engine start is essential for ensuring compliance with NATOPS standards.