Which of the following conditions requires an engine start to be aborted?

The requirement to abort an engine start is critical for ensuring the safety and functionality of the aircraft's engines. In this context, if no Inter-Turbine Temperature (ITT) indication is observed within 30 seconds after fuel flow initiation, it signals a failure in the start sequence. The absence of ITT means that the engine is not achieving the necessary temperature during the combustion process, which could indicate insufficient fuel combustion or an issue with the fuel delivery system. This lack of temperature progression suggests that the engine may not be starting as intended, and proceeding further could lead to potential damage to the engine or pose safety risks during the start phase.

On the other hand, positive oil pressure within 10 seconds, stable N1 and N2 speeds, or a successful engine start are all indicators of a healthy start sequence and do not warrant an abort. Positive oil pressure confirms that the lubrication system is functioning, stable speeds indicate that the engine is operating within the normal range, and a successful start is, by definition, the desired outcome of the engine start procedure. Thus, recognizing the scenario where ITT is absent provides crucial insight into critical engine management protocols.