A Collaborative Replacement-Spare Provision Policy for Three-State System Considering Inspection Errors

Inspection-based maintenance is critical for mitigating failure risks and enhancing maintenance efficiency. This study proposes a condition-based replacement-spare provision strategy considering two inspection errors, which is tailored for three-state deterioration depicted by delay time model. Specifically, 1) both the imperfect inspection, false positive as well as false negative errors, and actual health state determine the reported state; 2) the reported defective state triggers an ordinary ordering and a subsequent postponed preventive replacement supported by the accessible spare; (3) the emergent ordering is placed upon system failure if no prior ordinary ordering exists, thereby minimizing downtime losses. Inspection imperfection promotes the practicality of the proposed policy; and the condition-based selection between ordinary as well as emergent orderings enhances the decision effectiveness. The long-run cost rate is established and optimized by seeking the optimal inspection cycle length. Numerical experiments on railway bogie axle-bearings verify the strategy's applicability and superiority over conventional policies.