Competing risks and opportunistic informative maintenance

The present paper makes a link between the literature on competing risks and that of opportunistic maintenance. Three models for competing risk involving censoring through opportunistic maintenance are discussed. One is an existing opportunistic maintenance model, one is a new opportunistic variant on an existing competing risk model, and the third is a new model that captures the notion of opportunistic informative maintenance. These models show that even though opportunities may occur according to a process that is independent of the failure process, the appropriate competing risk models may still involve dependencies. This work was motivated by observation of practices in a coal-fired power plant consisting of four generating units, which is briefly described. Through simulation examples it is shown how these competing risk models can be used to support decision making about maintenance rules, and the identifiability issues associated with the models are discussed. Competing risk theory addresses statistical estimation problems which are a common concern in much of the maintenance literature, and focuses attention on non-age-related information available to maintainers.