Zero-emission hydrogen-powered regional aviation came a step closer on Jan. 19 when ZeroAvia flew a Dornier 228 testbed with a prototype fuel cell powertrain replacing one of its two turboprops. The 10-min. test flight was conducted from Cotswold Airport, England.

Attention now shifts to certification, as ZeroAvia plans to begin deliveries of its 600-kW hydrogen-electric engine, the ZA600, in 2025 for retrofit to 9-19-seat regional aircraft. The U.S.-UK startup is pushing for harmonization among UK, European and U.S. regulators so that it can launch simultaneously in multiple markets.

With a weight at takeoff of 5,650 kg (12,460 lb.), the modified 228 is the largest and heaviest aircraft to fly with hydrogen-electric propulsion. ZeroAvia previously flew a 200-kW demonstration system in a converted six-seat Piper Malibu.

On its first flight, the Do 228 reached 2,000 ft. and 120 kt., receiving 50% of the power for the left-side electric motor from the fuel-cell system and 50% from batteries. Gaseous hydrogen tanks at 350 bar and two multicell stacks are installed in the fuselage.

Rival Universal Hydrogen on Jan. 18 tweeted video of its hydrogen-electric testbed—a 50-seat De Havilland Canada Dash 8-300 with a 1-megawatt fuel-cell system replacing the right-side turboprop—conducting the first propeller spin ahead of its planned first flight at Moses Lake, Washington.

ZeroAvia is working with the UK Civil Aviation Authority (CAA) to establish the certification basis for the ZA600 but needs the regulations to be harmonized with the European Union Aviation Safety Agency (EASA) and FAA “as we are not targeting a single country for the entry into service,” says Gabriele Teofili, head of aircraft integration and testing.

The CAA will be the primary certification authority, but ZeroAvia is aiming for concurrent EASA and FAA validation. “There is a lot of attention to our certification basis and to have a common UK and EASA certification, but it’s not enough for us because we cannot launch only in Europe,” Teofili says. “So we will also pull the FAA toward the same schedule. We need to have a full harmonization.”

Results from ZeroAvia’s initial test campaign will feed into the final iteration of the ZA600 design that will be submitted to the CAA for certification toward year-end. The certified hydrogen-electric powertrain will use only the fuel cell for power, founder and CEO Val Miftakhov says.

ZeroAvia plans to announce its launch application soon for the ZA600, which is set to be a Part 23 aircraft in the 9-19-passenger class. A manufacturing site is to be selected this year, and small-scale series production should begin in 2024. ZeroAvia has 600-700 preorders for the ZA600, Miftakhov says, and has already signed a contract with Sweden’s PowerCell for serial delivery of fuel cell stacks.

The startup is working with more than 10 airports to prepare for the deployment of hydrogen-powered aircraft by its launch customers. “We believe the best approach is on-site production of hydrogen by electrolysis,” because it avoids the transportation of fuel over long distances, Miftakhov says. “This is the most economical way to produce fuel and also the fastest way to deploy such infrastructure.”

ZeroAvia is also developing a 2-megawatt-class hydrogen-electric powertrain for 70-80-seat regional turboprops. This powerplant would use cryogenic liquid hydrogen storage. Component testing is underway and integrated ground tests are expected to begin “in a few weeks,” he says, adding that the balance of ZeroAvia’s approximately 1,500 preorders are for this larger ZA2000 system.