Spares provisioning for repairable systems under fleet expansion

We consider a spares provisioning problem in which a fleet of identical repairable systems is acquired in stages over time. Each system comprises a series of line replaceable units (LRU) so as to achieve a high availability level. The first part of the paper deals with the methods for making statistical inferences on LRU reliability, and the second part deals with the policy of optimal spare unit provisioning based on the output of reliability analysis. In particular, in the former, we consider a realistic scenario when system failures are non-stationary and triggered by multiple s-dependent competing risks. In the latter, the inventory system dynamics are analyzed and an optimal spare provisioning policy is obtained.