OPTIMAL INSPECTION AND REPLACEMENT POLICIES WITH AGE-DEPENDENT FAILURES AND FALLIBLE TESTS

Optimal inspection and replacement policies for a device subject to no n-Markovian stochastic failures are derived in the case of inspections that may fail to provide a correct description of the state of the sy stem. Two types of policies are considered, differing in the strategy followed in case of reported failure: one-test policies prescribe repl acement, whereas two-test policies prescribe a more accurate work-up, designed to avoid the replacement of a functioning unit. For both case s and arbitrary failure distributions, general optimality conditions a nd algorithms that reduce the infinite horizon optimization to two dim ensions are derived. Properties of the optimal policy, like monotonici ty of the times between inspections, are studied. Methods for the impl ementation of fast computational algorithms are suggested.