“…The classic problem is still valid: how system reliability can be improved using mathematical modelling. In this area, many interesting articles and books have already been written [7,12,13,19,20,26]. Applications of mathematics, in particular probability theory and statistics, for problems of operation and maintenance of technical objects cover such issues as: planning of active and passive experiments, inventory management, analysis of data about failures [6,8], preventive maintenance policy optimisation, maintenance costs analysis, management of operation and maintenance processes.…”