An Analysis of the Fatigue Life of an Airplane Wing Structure under Overload Conditions

Results of an analysis to determine the effect of overload operations on wing fatigue life are presented. The investigation was confined to one transport-type airplane, which was assumed to operate at cruising power and with overload up to 50 percent of design gross weight. Overload weight concentrated in the fuselage was found to adversely affect the fatigue life, but overload weight distributed proportionally to the design gross weight had negligible effect on the fatigue life. The fatigue life, furthermore, was adversely affected by overload to a smaller degree than the single-gust life. As in the case of single-gust life, the wing-weight ratio was a main factor in determining the relative reduction of fatigue life by overload.