“…The greater number of PM is performed, the more reliable the component becomes, but there must be a balance between the cost and the benefit of each PM executed, since at some point the cost could be higher than the benefit. For this reason, in the last few years, the concept of maintenance has evolved to a new level called Smart Maintenance (SM), which includes smart-inspections [7], smart-devices [8] and smartservices [9], giving a scheduled and proactive maintenance. There is no well-established analytical method that allows to describe SM in mathematical terms.…”