Fatigue crack growth from flaws in combat aircraft

The 1969 in-flight failure of an F-111 wing due to the presence of a rogue manufacturing flaw precipitated the adoption of the damage tolerance aircraft design philosophy by the United States Air Force. This article compares this flaw to several flaws or initiating discontinuities that led to unexpected failures in combat-type aircraft operated by the RAAF and found these to be in general an order of magnitude smaller. Failure in the RAAF examples considered here were also dependent upon several other design and production factors in-addition to the initial discontinuity size.