The article proposes a variant of the method of determining the time of maintenance of military vehicles, which are in operation, in the repair period. A set of works was considered and carried out, which allows us to directly determine the timing of maintenance during the service life of military vehicles, which cause difficulties associated primarily with the need to assess the impact of maintenance on the parameter of the flow of failures and predict it changes, the methods of which are insufficiently developed. The analysis of the existing methodical apparatus of the decision of problems of substantiation of requirements to the efficiency of carrying out maintenance is carried out.