MULTIPLE FAILURES IN A MULTIITEM SPARES INVENTORY MODEL

Most inventory models dealing with spare parts assume independent part failures and hence one-at-a-time failure occurrences. In practice, for example when an aircraft engine undergoes repair, there is usually more than one part requiring replacement or repair; we denote this situation as 'multiple failures'. In this paper we represent multiple failures in a continuous, infinite horizon, order-for-order spares replenishment inventory model with cannibalization. We derive exact expressions for the distribution function and the expectation of the number of backlogged jobs; approximations are also provided. The results can be used to optimize spares inventories, to evaluate the effects of correlated failures, and to model the impact of parts commonality.