For the other items, the non-MSI, the ‘‘optimal’’ maintenance strategy is assessed to be operation until failure occurs and then to perform Corrective Maintenance (CM), i.e. Run-To-Failure (RTF). RTF might also be a relevant maintenance strategy for some of the MSI, depending on their failure and lifetime characteristics, failure consequences and maintenance costs.
For simple systems that include only a few items, it is in most cases quite obvious which of the items are important for the reliability of the system and what their failure consequences are, and the MSI may be identified without any rigid analysis.