What is an abnormal start indication that requires aborting a start?

The correct answer highlights a critical aspect of engine start procedures, particularly concerning the ITT (Interstage Turbine Temperature) limits. When initiating an engine start, it is essential to monitor the ITT closely because exceeding the specified temperature limits during start could lead to engine damage or failure. If the ITT exceeds the defined limits, it indicates an abnormal condition that could result in safety concerns. Therefore, aborting the start in this situation is not only precautionary but necessary to prevent potential harm to the engine and ensure safe operations.

In contrast, while an absence of oil pressure after 15 seconds may suggest a potential issue, it does not immediately necessitate a start abort if the engine is still in the initial phases of the start sequence. Positive oil pressure within 10 seconds is actually a normal indication and shows that the lubrication system is functioning correctly, which is reassuring. Lastly, having a stable N1 indicated before the starter cutout is part of normal engine operation and does not signal an abnormal condition requiring an abort of the start process. Each of these points underscores the unique circumstances surrounding the decision to abort an engine start, with ITT limits being a non-negotiable factor for engine safety.