The concept of condition-based gas turbine-powered aircraft operation is realized all over the world, which implementation requires knowledge of the end-of-life information related to components of aircraft engines in service. This research proposes an algorithm for estimating the equivalent cyclical running hours. This article provides analysis of the existing methods of cycle counting and suggests a new original method. It implies consideration of two cycles related to the chain of extrema "max-min-max". The first is the main simple loading cycle; another cycle is the additional from the minimum to the lowest extrema. It is assumed that the "global" minimum is known. The authors developed the algorithm aiming at allocation of separate simple loading cycles in a complex life cycle, implemented by using Visual Basic for Applications and Excel'97. The paper also provided the method of bad records rejection and evaluation of the stress-strain behavior of the main engine components--drive shafts, discs and blades based on regular measurements of temperature and pressure in the gas stream. These methods allow calculating the accumulation of damage on a real-time basis. The developed algorithms laid the foundation for an automated diagnostic system of an aircraft engine.