Reliability [2] [3] [4] [5], safety [6] [7] and maintenance management [8] [9] [4] are some of the most
interesting issues of international scientific research and have been deeply analysed by the authors. In particular,
the planning of maintenance activities is one of the core elements in the design of a production system [10] [11]
[12]. The production process, in fact, flows regularly if the different systems are available when required by the
production plan. All the maintenance operations, for this reason, have to be organized and scheduled so that they
can be planned in time according to the production plan. Despite the planning phase, such schedule cannot
remain the same over time because any unplanned emergency maintenance action causes its modification [13].
Anyway, it is still important to have a basic maintenance activity schedule, mainly to coordinate production with
the planned maintenance stops. In this regard, the choice of when carrying out a scheduled maintenance
operation can be done according to different approaches. One is the Reliability Centred Maintenance (RCM)
[14][15][16][17]. It is a technique for developing a program of preventive maintenance (PM) activities [15],
which was born in aircraft industry and later spread in all the other sectors. The main goal of RCM is to
decrease maintenance costs, removing all the PM activities that are unnecessary. While in the most cases the
maintenance decisions derive by legislation, recommendations from manufactures and company standards,
RCM focuses on the failures and functional degradation of the system considered: system reliability is the focus
of the maintenance planning. RCM may be implemented through some steps [15]: after the selection of the
specific system, a functional failure analysis in developed to identify the potential system failure modes,
according to one of the many classification of failure modes [18] presented in literature. Then the critical items
are selected and, with the data collected over time, a FMECA analysis is fulfilled. The next steps are the
selection of the appropriate maintenance actions and, finally, the determination of preventive maintenance
intervals. The choice of the maintenance type to adopt for a specific system is one of the more difficult tasks,
since there is not an unique clear rule to help. RCM considers the main failure modes emerging from the
FMECA as the basis for the selection of the maintenance type. The main plight is to understand whether a PM
activity is favourable or it would be better to replace an item after its failure with a corrective maintenance
action (CM). The maintenance activities can be classified according to the grouping proposed by UNI 13306
[19], which identifies, among others, the corrective maintenance actions and the preventive ones. Preventive
maintenance can be carried out in accordance with specific time intervals (without specific condition
investigation) or considering the real condition of the system: in the first case we call it predetermined
maintenance, otherwise it’s called condition based maintenance (CBM).