Analysis of a multi-part spares inventory system subject to ambiguous fault isolation

This paper considers a multi-part spares inventory model for a maintenance system composed of a spares-stocking centre and a repair centre. In the maintenance system, multi-part spares are jointly needed to repair faulty end items determined by ambiguous fault isolation done by the built-in-test-equipment. If any operating end item breaks down, then all associated parts should be replaced either iteratively (one at a time) or altogether. In the case of iterative replacement, failed parts are detected in the field after fixing the broken end item. However, in the case of group (altogether) replacement, all removed parts are sent to the repair centre where the failed part is detected and fixed. The repaired or non-failed parts are then restocked at the spares-stocking centre. For the system, this paper is to derive the exact expressions for the distribution function and the expected numbers of the backlogged end items under the cannibalization policy. These expressions are then used in the optimization of the associated spares' inventory level. Illustrative numerical examples are also presented.