New Air Force Requirements for Structural Safety, Durability, and Life Management

The past five years have seen significant changes in the Air Force philosophy and approach in achieving structural safety and durability in military aircraft. These changes have been motivated by problems of high cost, late system development programs, with a high level of in-service structural maintenance and modification costs (poor durability) and, in some cases, less than desired fracture resistance (poor damage tolerance/safety). The problem area has been attacked along a number of avenues; one major thrust has been a thorough examination and revision of the structural design and test specifications, the MIL-A-8860 series. In this paper, certain aspects of the overall problem are discussed; an overview of the pre-1969/70 Air Force approach is presented, along with its short-comings; and, finally, significant aspects of current policy are listed, giving comparisons with the old requirements.