Important problem of turbomachinery maintenance is evaluation of blades condition. As the rotating speeds become higher and higher, the blades are exposed to more and more severe failures, such as ruptures, creep deflection, high-cycle fatigue, oxidation, erosion, rubbing, wear, foreign object damage. If appear, these negative factors will change the strength parameters of the blades, lead to machine damage, and finally result in a serious accident. Therefore, efficient methods of blades condition evaluation are needed, and even minimal improvements of known diagnostics techniques may give a chance to detect a failure, and warn the staff, before the advancement of this failure becomes serious.In the paper an extension of the previously developed method based on differences in phase shifts of measurement signals is proposed, and experimentally tested. An extended definition of diagnostic thresholds is introduced, and two different diagnostic states are specified. These are technical condition and stationarity condition of a machine. It is demonstrated that only simultaneous analysis of these two conditions assesses the actual blades condition properly, and gives rationale to take a decision about a potential overhaul of the machine.