What indicates that you should abort a start due to N2 Stagnation?

The situation pertaining to N2 stagnation during an engine start is critical, as it often indicates that the engine is not functioning correctly and may not produce the necessary thrust even after start attempts. The correct answer pertains to the observation of initial light off followed by a deceleration of engine parameters.

In the context of an engine start, "light off" refers to the moment when combustion begins in the engine. If light off occurs but is soon followed by a deceleration, this illustrates that although ignition took place, the engine is not able to sustain the required speed for both N2 (the high-pressure rotor) and the overall thrust generation. This scenario typically indicates that the engine is unable to maintain or increase RPM, suggesting that the engine may not be stable and could lead to potential issues if the start is continued.

The presence of fuel flow alone does not guarantee a successful start, as conditions such as air supply or combustion chamber issues could still prevent proper engine operation. A stable ITT indicates that the temperatures are within normal operating ranges, but does not directly provide information necessary for assessing N2 performance. Excessive oil pressure is usually indicative of potential mechanical issues but does not specifically relate to N2 stagnation directly affecting start decisions. Thus, the clear