Abstract : The occurrence of catastrophic helicopter accidents due to Bell Model 540-11-250-1 main rotor blade structural failure triggered an Army-wide inspection to determine the condition of the existing 540 blade, and full-scale testing to verify the 1100-hour fatigue life of the Model 540 main rotor blade was conducted at the Eustis Directorate. Three Model 540 blades, each having varying bond/debond conditions and numbers of accumulated flight hours, were fatigue tested. Existing inspection techniques for bond/debond detection were used and evaluated, with emphasis placed on nondestructive test techniques.