SEQUENTIAL IMPERFECT PREVENTIVE MAINTENANCE POLICIES - A CASE-STUDY

In this paper, two preventive maintenance (PM) policies for the bus engines of a transport network have been considered. Based on the mean time to failure (MTTF) data of the engines of a particular make and model, maintenance policies are developed where the failure rate of the engines does not exceed the pre-determined level of maximum failure rate. In policy 1, the system has a different failure distribution (Weibull) between PMs, and in policy II, each PM reduces the effective age of the system. The number of PM interventions and their schedule times, which minimize the expected mean cost rate over an infinite time horizon for both the policies, have been discussed. Finally, numerical illustrations and the effect of cost factors on the number of PM interventions and the expected cost rates have been presented.