It is proposed to develop an accurate in-service aircraft engine life monitor system for the prediction of remaining component and system life for aircraft engines. Once proven in the aircraft engine environment, this life monitoring system will be used in a wide variety of airborne and land-based air-breathing engine systems. The aircraft engine life monitoring system will include three separate algorithms: an in-flight service monitoring algorithm, a pre-flight and post flight engine analysis algorithm, and a component-life tallying algorithm. The in-flight service monitor will treat the engine as a whole in response to sampling data of torque, speed, temperature and time. The engine analysis algorithm will determine the engines' operation parameters from those of its components. It also will determine the life and reliability of individual components based on the service monitoring algorithm's output. The component-life algorithm will accumulate life and reliability tables. The Phase I effort will develop the life-monitoring and supporting life-estimation and reliability algorithms. In Phase II effort, the full life-estimating system will be specifically tailored, assembled and tested with a commercial aircraft engine.