The development cycle of an aero gas turbine engine consists of various phases like light-up phase, acceleration from light-up to idle speed phase, idle speed phase, intermediate thrust phase, reheat thrust phase, etc. The start cycle phase, in general, is the most critical phase. During the development cycle, the problem of classifying a test as acceptable or otherwise depends to a large extent on the model that one has for this phase and subsequent post test analysis which could be a time consuming and repetitive procedure. The start cycle performance of a typical aero gas turbine engine under development has been considered. The difficulties in developing a realistic model of the engine during the start cycle phase are highlighted. The engine parameters involved in the light-up and acceleration upto idle speed phase have been taken into account for a set of typical engine runs. An approach for appropriate weightages/membership functions for the engine parameters has been formulated and the control rules arrived at. Using this approach, the parameters observed in a given engine run are fed in and an attempt is made to classify the engine performance in the phase as acceptable or not. This formulation has been found to be highly successful in the categorisation of engine runs during the development cycle of an engine program. © 1996 - Elsevier Science B.V. All rights reserved.