The V-22 full-scale wing/fuselage test article recently completed 20,000 effective flight hours (EFH) of low-cycle fatigue loading, equivalent to two lifetimes, as part of the program qualification test requirements. This test represented one of the most complex structural test programs in military aviation history, integrating both maneuver sequence and transient vibratory loading into a series of coordinated discrete load conditions that employed 127 hydraulic actuators and a complex loading fixture. During the program, a number of failure modes were induced that revealed both airframe and test design limitations. These failure modes also provided data to establish fleet inspection/repair requirements and the basis for potential product improvements. This paper will provide an overview of the test program, including load spectrum development, test fixture development, failure mode identification, investigation procedures and other test uses, such as cost reduction initiatives and investigative activities. In light of this overview, a summary of lessons learned will be delineated, covering both airframe fatigue design and full-scale test design practices.
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