The purpose of this SAE Aerospace Information Report is to disseminate qualitative information regarding foreign object damage (FOD) to gas turbine engines used to power helicopters and to discuss methods of preventing FOD. Although turbine-powered, fixed-wing aircraft are also subject to FOD, the unique ability of the helicopter to hover above, takeoff from, and land on unprepared areas creates a special need for a separate treatment of this subject as applied to rotary-winged aircraft.