Basic terms and concepts of the reliability theory of the systems are examined that are characterized by multilevel serviceability. It is assumed that the system with multilevel serviceability besides the serviceable and faulty states can be in one of the partially serviceable ones. The concepts of quality indices and functioning efficiency are introduced for the system with multilevel serviceability. For such systems, their separate, complex and multilevel reliability indices, presented in a vectors and matrix form, are determined.
complex technical system, multilevel serviceability