Defect tolerance assessment of a helicopter component subjected to multiaxial load

In this paper a simple but effective methodology for the defect tolerant assessment of a structural component is presented. The methodology is based on the experimental evidences available in literature that at the fatigue limit non-propagating cracks are observed near defects present in the metallic material. The evaluation of the threshold stress intensity range of these short cracks allows to calculate a safety factor with respect to their propagation. The methodology is applied to the tail rotor hub of a helicopter. The complex geometry and load conditions make this component very interesting for the defect tolerance assessment. The application to an engineering problem allows to describe the difficulties that arise in this process and to show the possible solutions that can be adopted.