Structural properties of machinery elements and sub-assemblies are often used for diagnostic purpose. Occasionally in engineering practice for some technical objects there is no description of distribution of structural parameter values available. Results of experimental evaluation of this distribution are difficult to be applied for diagnostic purpose as a result of lack of a reference distribution for comparison purposes. Nevertheless, for some technical objects, the inherent properties of the structural parameter values distribution may be used in such a case. In the paper an example of a rotating shaft is considered for which the axial symmetry of structural parameter values distribution is expected. Application of impact testing for the purpose of identification of the modal model is an easy way to check this symmetry and to use the results for diagnostic purpose. The technique applied to an example shaft indicated its failure but proved to be inefficient in localization of the failure.
