A Method of Estimating the Permissible Fatigue Life of the Wing Structure of A Transport Aircraft

Abstract

For types of structure where safety standards cannot be preserved by reliance on inspection, a permissible “safe life” has to be determined by relating the loads experienced by the aircraft in service to the fatigue performance of the structure, with due allowance for scatter in fatigue strength and in the frequency with which loads are encountered. This paper gives a working method for estimating the “safe life”—at which the risk of fatigue failure is negligible—of the wing structure of a transport aircraft, where the flight loads giving rise to fatigue are overwhelmingly due to atmospheric turbulence but where allowance has also to be made for “ground-to-air” loads.