The Helio H-550 Stallion was an STOL utility aircraft developed in the United States in the 1960s. Initially conceived as a turboprop-powered variant of the Helio Courier it eventually emerged as a completely new design of the same general configuration. It was a much larger aircraft than the Courier and Helio soon discovered that it was too expensive for the market. The USAF however emerged as a buyer for the design purchasing the aircraft for the Credible Chase programme as the AU-24A.
Made by Helio Aircraft Company.