On the coordinated random group replacement policy in multivariate repairable systems

We study a system with multiple components and preventive maintenance. At predetermined times, some of the components are replaced with new ones. We permit the set of components that are chosen for replacement to be random and study the effect of dependency in this selection. For example, we show that it is often better to have simultaneous replacements of components, rather than replacing each component independently of the others. We also show that preventive maintenance only makes sense for components whose lifetimes are new-better-than-used (NBU).