Universal Hydrogen flew a 40-passenger regional airliner using hydrogen fuel cell propulsion. The airplane, nicknamed Lightning McClean, took off from Grant County International Airport and flew for 15 minutes, reaching an altitude of 3,500MSL. The flight, conducted under an FAA Special Airworthiness Certificate, was the first in a two-year flight test campaign expected to culminate in 2025 with entry into passenger service of ATR 72 regional aircraft converted to run on hydrogen. In this first test flight, one of the airplane’s turbine engines was replaced with Universal Hydrogen’s fuel cell-electric, megawatt-class powertrain. The other remained a conventional engine for safety of flight. The flight was piloted by Alex Kroll, an experienced former US Air Force test pilot and the company’s chief test pilot.The company’s powertrain is built around Plug Power’s ProGen family of fuel cells specially modified for aviation use. One of the unique aspects of the design is that the powertrain does not use a battery—the fuel cells drive the electric motor directly drastically reducing weight and cost. The motor, a modified magni650 electric propulsion unit, and power electronics were supplied by Everett-based magniX. Seattle-based AeroTEC assisted with engineering efforts, including design of the modified nacelle structure, aircraft systems design and integration, as well as aircraft modifications and installation of the Universal Hydrogen powertrain onto the flight test aircraft, accomplished in less than 12 months.