A Survey of U.S. Army Helicopter Main and Tail Rotor Blade Obstacle Strikes

A survey of main and tail rotor blade obstacle strikes that resulted in damage-causing mishaps was conducted. The survey is based upon the experience of three Army helicopters (UH-1, AH-1, and OH-58) during the period January 1974 through February 1980. This period was chosen because it reflects the increased emphasis on terrain flight training in a peacetime environment. For each aircraft, main and tail rotor strikes were analyzed with respect to flight modes, mishap costs, mishap frequency, and casualties. Design criteria for future systems are suggested which (1) could prevent these mishaps, or (2) would make the aircraft more tolerant of obstacle strikes. These data are presented on the premise that increased aviator knowledge of the problem will prevent some mishap and that increased industry awareness will result in improved design for obstacle strike tolerance and avoidance in future helicopter systems.