The first phase is a screening phase, where the number of
items for analysis is reduced. The purpose of this phase is to identify the Maintenance Significant Items (MSI), i.e. the items we later feed into the RCM logic for specification of PM tasks. These items are identified from criticality rankings performed for each of the items, where all functional failures for each of them are assessed, assuming that all other items are functioning perfectly. Typically a type of qualitative ranking is used based on a criticality matrix including information on the various failure modes, failure frequency and consequences. The assessments are performed on an overall system level, for the following conse- quence categories: