Abstract
Reliability analysis is an integral part of system design and operation. The study of maintenance based on the reliability requires prior modeling of the degradation of the considered system. This is a difficult task when the system becomes complex. The first step consists in exploiting the Return EXperience (REX) databases and the experts knowledge and advice to estimate the parameters of the model of degradation of the chosen system. The model of degradation is then, enriched taking into account maintenance operations. Once the system and its maintenance are properly formalized, a utility function is established in order to evaluate a given maintenance strategy according to one or more given criteria.