The current methods of vibration adjustment and monitoring with experimental approach do not always let us solve the arising problems related to vibrational reliability control of turbine generating units in use. In solving the problem data an integrated approach is provided by the authors. It is being a modeling and experimental complex. Application results of the named study, connecting to the vibration reliability control of TGV-200-2M turbine-generator and GTN-16 gas turbine set, are demonstrated in the article. The approach is shown to be effective. During the authors’ investigations fundamentally new knowledge about dynamic characteristics of a flexible rotor on mass-elastic supports, including the influence of their parameters on the unit dynamic properties was got. Feasibility of additional critical speeds in a “rotor-bearing-support” dynamic system resulting from repeated flexural modes in the range of rotation frequencies (double (twin) modes) is shown and experimentally-confirmed. The obtained results can be used for defect diagnostic indicators that are connected to the turbine set support system. The named indicators can also be implemented into in-service vibration monitoring systems.