Generalized Preventive Maintenance Policies for a System Subject to Deterioration

Preventive maintenance models are proposed for a system with two types of units operating s-independently and subject to deterioration. The system undergoes minimal repair on type-1 unit failure and is replaced on type-2 unit failure. Three policies which minimize average costs including the earning loss due to deterioration are discussed; one is based on the cumulative operating time, a second on the number of minimal repairs performed, and the other on both.