Coordinated condition-based repair strategies for components of a multi-component maintenance system with discounts

This paper presents a heuristic algorithm for computing upper and lower control limit values for the repair of components (which need not be identical) in a multi-component system. The cost structure is composed of repair, operating and failure costs. An essential feature of the model is that reduction in repair costs can be achieved by coordinating the repair of several components and thus paying set-up costs only once. The algorithm searches for a simple rule per component in order to minimise long-run average cost per unit of time for the system as a whole. This opportunistic rule per component has a simple structure: it consists of an upper limit inducing mandatory repair and of several lower limits. Each lower limit corresponds to the potential for saving an amount of repair costs when an opportunity for a specific coordination presents itself. The heuristic procedure is based on decomposition producing single-component problems. Each single-component problem is solved as a Markov decision problem, allowing the model to cope with a large number of components.