Abstract: A decision model of opportunistic maintenance based on dual time window strategy is proposed for the multi-unit serial system. Instead of taking the arrival of a single unit’s optimal maintenance interval as the system shutdown condition in traditional single window strategy, dual time window strategy takes it as the trigger condition in maintenance decision. It decides the best maintenance equipment combination based on the maintenance time window for unit grouping, and introduces a new maintenance time window for preventive maintenance implementation to optimize the system downtime. On the basis of dual time window, the optimal maintenance strategy of the system is obtained by minimizing total maintenance cost of the system during the planning period. The example analysis shows that the dual window strategy is better than the single window strategy on total maintenance cost.

Key words: multi-unit serial system; preventive maintenance; opportunistic maintenance; maintenance cost; maintenance time window