As a series system, long-term availability of equipment may be computed as the product of parts availability. Considering data presented in Table 2, system long-term availability results in 91.1%, which implies 32 h per month of downtime. For the current scenario, simulation indicates 17 h of overtime (see next subsection, Fig. 3 (c), demand¼12 h/day,1 MTTF,1 MTTR). This matches the computed system downtime, since a fraction of downtime (roughly 50%) is carried out during regular production hours while the remaining fraction leads to overtime.