Numerical calculations show that the distribution of stresses and deformations in the shaft with flange was in accordance
with the expected ones. Width of the maximum stress zone, obtained by the Finite element analysis, strongly correlates with
the width of the zone determined by non-destructive inspection. The maximum normal stress in the critical point of the
transient radius at static load, during start of operation and change of runner blades’ position, is 119 MPa, which gives high
safety factor in comparison with the obtained yield stress of 310 MPa. The obtained value for the normal tensile stress of
47.8 MPa during normal shaft operating regime is less than the test value of the fatigue limit of 168 MPa, so the cause of
initial cracks occurrence cannot be found in the shaft properties. The level of normal stresses during start of operation
(119 MPa) is approximately 75% of fatigue limit, which was insufficient safety margin for ‘‘wet’’ environment.