ZeroAvia’s modified 19-seat Dornier 228 twin-engine aircraft took to the sky in testbed configuration for first flight as part of the HyFlyer II project. The airplane was retrofitted with a full-size prototype hydrogen-electric powertrain on the left wing of the aircraft.

The flight took place from the company’s R&D facility at Cotswold Airport in Gloucestershire, UK, and lasted 10 minutes. The aircraft completed taxi, take-off, a full pattern circuit, and landing. The landmark flight forms part of the HyFlyer II project, a major R&D program backed by the UK Government’s flagship ATI Program, which targets development of a 600kW powertrain to support 9-19 seat aircraft worldwide with zero-emission flight.

The twin-engine aircraft was retrofitted to incorporate ZeroAvia’s hydrogen-electric engine on its left wing, which then operated alongside a single Honeywell TPE-331 stock engine on the right.

In this testing configuration, the hydrogen-electric powertrain comprises two fuel cell stacks, with lithium-ion battery packs providing peak power support during take-off and adding additional redundancy for safe testing. In this testbed configuration, hydrogen tanks and fuel cell power generation systems were housed inside the cabin. In a commercial configuration, external storage would be used and the seats restored.

All systems performed as expected. This is the largest ZeroAvia engine tested to date, and places the company on the direct path to a certifiable configuration to be finalized and submitted for certification in 2023, with this programme also serving as key to unlocking speedy technology development for larger aircraft.

ZeroAvia’s 2-5 MW powertrain programme, already underway, will scale the clean engine technology for up to 90-seat aircraft, with further expansion into narrowbody aircraft demonstrators over the next decade.

​This flight test campaign is being conducted under a full Part 21 flight permit with the UK CAA, which is a much more stringent set of requirements compared to the E-Conditions framework ZeroAvia used for its 6-seat prototype test flights in the prior years. This signifies the maturity of the company’s processes and design approaches and its readiness to proceed towards full commercial certification of its powerplants.

ZeroAvia will now work towards its certifiable configuration in order to deliver commercial routes using the technology by 2025. The Dornier 228 will conduct a series of test flights from Kemble and later demonstration flights from other airports. Almost exactly two years ago, ZeroAvia conducted the first of more than 30 flights of a six-seat Piper Malibu aircraft using a 250kW hydrogen-electric powertrain.

The hydrogen-electric powertrain on board was fueled using compressed gaseous hydrogen produced with an on-site electrolyzer. To enable hydrogen production on site, ZeroAvia and HyFlyer II partner the European Marine Energy Center (EMEC) have delivered and operated the Hydrogen Airport Refueling Ecosystem (HARE), a microcosm of what infrastructure will look like in terms of green hydrogen production, storage, refueling and fuel cell powered flight. The system’s electrolyzer capacity was doubled earlier this year from its initial design for the latest project.

ZeroAvia’s HyFlyer II programme to develop its ZA-600 hydrogen-electric engine and retrofit the Dornier 228 is being delivered in partnership with EMEC and Aeristech and is supported by the UK Government through the ATI Programme and the Department for Business, Energy Industrial Strategy, Innovate UK and Aerospace Technology Institute.