Based on the Model 269 helicopter, which first flew in 1956, the TH-55A Osage was the first military aircraft production program for the Hughes division acquired by McDonnell Douglas in 1984. The TH-55A was selected by the U.S. Army in 1964 to be its primary helicopter trainer. In two decades the piston-powered Osage trained more than 30,000 Army pilots while logging over three million flight hours.