The Challenge Of Standardizing Fatigue Methodology

Historically, the development of the aircraft industry has been characterized by diversity which was the necessary by-product of many individual innovators. This has perpetuated itself in the area of fatigue methodology. The purpose of thi s paper is to present some of the details of the Sikorsky methodology and to address the worthy goal of standardization of fatigue methodology as applied to rotary wing aircraft. This is done in the context of the solution of a hypothetical fatigue problem. From the standpoint of approval agencies, the evaluation of differing individual manufacturer's applications and methods requires careful review in order to assure that certification goals are met. It has been alleged that this agency review of diverse fatigue substantiation methods has the disadvantages of increasing the review burden for the agencies, and in some cases that the diversity results in over-conservatism and added program costs. (Wolf and Arden-Reference 1)