In this article is proposed a new approach to the classification of the technical state of aircraft gas turbine engines in the course of their life cycle. Given classification takes into account the occurrence of new kinds of technical conditions of the engine, which arises during the operation of aircraft equipment upon technical state. For faulty operating condition and for efficient operating condition is introduced the concept of critical and non-critical state. The article shows how is changing in the process of operation functionality of the engine, provided in the form of a curve with a characteristic areas and breakpoint for operation of the engine. This introduced breakpoint for operation of engine corresponds to its state before the failure state. There were introduced, on the basis of changes in the degree of functionality of the engine, certain technical conditions into which aircraft engines can enter and stay. The introduction of technical The article presents diagram of possible transitions from one condition of the engine are described mathematically on theoretic-plural level. The article presents diagram of possible transitions from one engine technical state to another affected by both the operational and external control factors.