The engine flew for the first time in February 1977 when it replaced one of the four Pratt & Whitney JT8D engines on the McDonnell Douglas YC-15, an entrant in the Air Force's Advanced Medium STOL Transport (AMST) competition. Soon after, the second CFM56 was mounted on a Sud Aviation Caravelle at the Snecma flight test center in France. This engine had a slightly different configuration with a long bypass duct and mixed exhaust flow, rather than a short bypass duct with unmixed exhaust flow. It was the first to include a "Thrust Management System" to maintain engine trim.