Smart scheduling for better repair-depot reliability

Linton et al. (1995) use an expression for the reliability of the system for repairing failed units (FU) at a repair depot to compute the longest repair time for a newly failed unit (NFU) which assures a given reliability level (also termed the NFU supportability turnaround time or STAT) in terms of the constant failure rate for all components, the number of spares on-hand, and projected downstream repair completion times for FU. Since subtraction of the repair time for a NFU from its STAT-value yields the NFU's latest repair start-time (RST) which assures a given repair-depot system reliability (RD-SR), STAT-values are important for scheduling RST. If a NFU's latest RST is negative, however, the NFU cannot be repaired and returned to the status of a spare in time to assure the desired RD-SR level. When a NFU's latest RST is negative and some previously FU have not yet begun their repair, then Sched-Alg (the algorithm in this paper)-(i) shows whether or not it is possible to reschedule RST for FU so that the latest RST for the NFU is nonnegative (and, hence, the desired RD-SR can be maintained) and, if a reassignment of RST to meet RD-SR is possible; and (ii) determines a new RST schedule for FU which ensures the desired RD-SR, minimizes the number of adjustments required, and reduces the total adjustment time. Numerical examples illustrate Sched-Alg.