Risk-based condition assessment and maintenance engineering

Abstract

This chapter presents a paper that illustrates how probabilistic physics-based models can be used for risk-based condition assessment and life prediction of aircraft components—including the uncertainties in maintenance activities. Probabilistic modeling includes all significant uncertainties that affect engine reliability, such as flight conditions, loading history, manufacturing deviations, material properties, and behavior under random loading and maintenance activities. Maintenance uncertainties include those related to NDI techniques and operator's skills. This paper shows the uncertainty effects of different NDI techniques, maintenance intervals, and operator skills on engine reliability. Unscheduled maintenance rates are computed for given a maintenance schedule. STI has developed a physics-based stochastic approach to maintenance engineering that is based on the detailed integration of all design and post-design aspects and uncertainties that include manufacturing variabilities, maintenance activities, and cost aspects. By developing physics-based stochastic models for idealizing the operating environment, aero-thermal loading, structural behavior, and material progressive damage under variable loading, the maintenance engineering and cost analysis is approached from an advanced physical understanding and modeling of the engine behavior. Only by using such a physics-based stochastic approach, the engine life-cycle cost process can be adequately understood and controlled from the design stage.