ABSTRACT
This chapter describes a repairable system with continuous lifetime distribution and two different failure types. The two failure types are minor failures and large failures. The minor ones can be repaired by minimal repair and the large ones can only be dealt with through replacement. Furthermore, preventive maintenance is undertaken at predetermined periodic times with interval τ. The modelling of the different failure types is analogous to F. Beichelt who is the pioneer in using different failure types in the modelling of maintenance models. The chapter also describes stochastic processes in continuous time to model the system. In the literature, there are multiple maintenance models that consider different failure types and there are many ways to distinguish between the failure types. The maintenance policy is a direct generalization of the one dealt with in Beichelt. The optimization criterion of interest will be the average maintenance cost per unit time.
