Modified Reliability Centered Maintenance Analysis Considering Probability of Detection

Abstract

In the maintenance of aircraft structural parts, a routine inspection is conducted to prevent fatigue crack growth beyond the critical size during the service life. Traditionally, the inspection interval is determined by a reliability centered maintenance analysis (RCMA), which accounts for the stochastic nature of crack growth. In a practical nondestructive inspection (NDI), however, the probability of detection curve should be considered as well to reflect the detectability during the inspection. In this paper, a new RCMA is proposed that incorporates this. Despite the modern simulation approaches available in recent years, the highlight of the method is that all the equations are developed in an analytical way, which may be more useful in the real field of maintenance. Two examples are given to illustrate the applications: one is to determine the repeat inspection interval under the four POD curves in the NDI; and the other is to determine the maximum operation time until the next inspection, when an aircraft had an earlier inspection packaged with others. As a result, more appropriate inspection plans are obtained than the existing RCMA in terms of reliability and availability.