Inference and test in modeling the failure/repair process of repairable mechanical equipments

In many practical situations, repairable mechanical equipments are subjected to repair actions which significantly depart from both the minimal repair and the perfect maintenance assumptions. In this paper, two point processes are proposed, which allows the failure pattern of repairable equipments subjected to imperfect or hazardous maintenance and experiencing reliability improvement or worsening to be analyzed. Maximum likelihood estimators and testing procedures for the departure from minimal repair and perfect maintenance hypotheses are discussed. Numerical examples are also given to illustrate the use of the proposed models and procedures. Finally, results of a large simulation study are shown in order to assess the accuracy of the proposed inference and testing procedures for the small and moderate sample sizes encountered in practice. (C) 1999 Elsevier Science Ltd. All rights reserved.