It was the first hydrogen-powered helicopter to complete a full operational circuit – takeoff, climb, pattern flight, approach, and landing – under real-world conditions.

That distinction matters more than it sounds. A previous test in March 2025 had already shown the system could hover for just over three minutes. Impressive, but hovering is not flying. The April flight was the difference between a lab result and a proof of concept regulators can actually use.

Behind the milestone is Unither Bioélectronique, a Canadian subsidiary of biotech company United Therapeutics, and its Project Proticity program. The goal isn't tourism or air taxis – it's delivering transplant organs.

"This milestone shows that piloted hydrogen-electric vertical flight can move from theory to repeatable, safe, real-world testing," said Mikaël Cardinal, vice president of program management & business development, organ delivery systems for Unither Bioélectronique. "For Unither, the goal is clear: build the aircraft and aerial logistics systems needed to help deliver manufactured organ alternatives to patients in need while creating a scalable zero-emission transportation network."

The prototype swaps the R44's conventional combustion engine for a compact electric powertrain built around two PEM (Proton Exchange Membrane) fuel cells – devices that convert hydrogen and oxygen into electricity, producing only water as a byproduct – housed in the rear cabin. A magniX electric motor sits in the original engine bay, and a lithium-ion battery pack handles sudden power spikes, like during takeoff or sharp maneuvers.

During early flights, the system hit a peak output of around 178 kW (239 hp), with roughly 155 kW (208 hp) at the rotor shaft during hover. More than 90% of that power came from the fuel cells, with the battery covering the rest.

The current version runs on compressed gaseous hydrogen, which is limited by tank volume and energy density. But the company's target is liquid hydrogen (LH2), which stores far more energy in the same space and is essential for long-range missions carrying the kinds of payloads needed for organ transport.

The next step is scaling the entire architecture up to the Robinson R66, a larger turbine-powered platform better suited to earning type certification – the formal regulatory approval that clears a design for commercial production – from Transport Canada and the FAA. The target range is between 200 and 250 nautical miles (370 to 463 km).