Condition-based maintenance at both scheduled and unscheduled opportunities

TL;DR

This paper develops an optimal condition-based maintenance policy for a single component with scheduled and unscheduled opportunities, balancing costs and system states to minimize long-term expenses.

Contribution

It introduces a control-limit policy framework that accounts for scheduled and unscheduled maintenance opportunities, providing explicit cost calculations and policy comparisons.

Findings

Optimal policy is a control-limit policy depending on time until next scheduled opportunity.

Explicit formulas for long-run average costs under various policies.

Numerical comparisons demonstrate policy effectiveness.

Abstract

Motivated by original equipment manufacturer (OEM) service and maintenance practices we consider a single component subject to replacements at failure instances and two types of preventive maintenance opportunities: scheduled, which occur due to periodic system reviews of the equipment, and unscheduled, which occur due to failures of other components in the system. Modelling the state of the component appropriately and incorporating a realistic cost structure for corrective maintenance as well as condition-based maintenance (CBM), we derive the optimal CBM policy. In particular, we show that the optimal long-run average cost policy for the model at hand is a control-limit policy, where the control limit depends on the time until the next scheduled opportunity. Furthermore, we explicitly calculate the long-run average cost for any given control-limit time dependent policy and compare various policies numerically.