Clean Aviation has not ruled out providing funding for future flight tests of hydrogen technologies on smaller commuter-category aircraft – despite being outside the EU body’s remit – provided developers can prove scalability onto larger platforms.
Honeywell, which is leading such a project in Clean Aviation’s first phase, had recently expressed concerns that funding for flight testing would be limited unless it selected a CS-25 aircraft as a testbed.
Clean Aviation’s remit has always been on transport-category aircraft – those with 19 seats and above – but in the regional segment its focus is increasingly on the upper end of the space, looking at technologies for a zero-emission successor to the ATR 72-600 twin-turboprop.
But Sebastien Dubois, Clean Aviation head of unit, programme development and communications, has moved to reassure interested parties over the path to flight testing that will likely be contained in its next call for proposals in February 2026.
“For the moment, we are agnostic in terms of demonstration strategies,” he tells FlightGlobal.
While the call will specify that any hydrogen fuel cell propulsion system should be based around the requirements of a larger regional aircraft, it will not preclude testing on a smaller platform, he insists.
“If it is relevant to have a one-stop-shop to perform validation on a CS-23 platform while maintaining the objective of CS-25 and demonstrating a stepping-stone approach, at that stage I would say ‘why not?’.”
Maria Calvo, head of unit project management at Clean Aviation, says the “scalability and exploitation” of the system under development are key.
“It’s not a demonstrator for the sake of demonstration, but it’s a demonstrator with a target that it could be applied to a CS-25 aircraft and is a scalable solution,” she says.
Although hydrogen topics were absent from Clean Aviation’s third call, released earlier this year, they will account for a little under one-third of the total available in call four.
In addition to the Honeywell-led NEWBORN project, which aims to ground test a 1MW-class fuel cell powertrain next year, Clean Aviation has also funded HEROPS, a project co-ordinated by MTU Aero Engines that is developing a similar 1.2MW fuel cell powertrain; both conclude in 2026.
Honeywell is leading the NEWBORN work from its site in Brno, the Czech Republic. Speaking to journalists at the site in late September, Ondrej Kotaba, the firm’s senior technology fellow, said first introducing hydrogen propulsion on smaller aircraft seemed the most logical approach.
“Our opinion is that [hydrogen] will not get to CS-25 unless it is first proven in the CS-23 world,” he added.
Although reiterating that Clean Aviation will not fund development work aimed at sub-19-seaters, Dubois thinks there are broader benefits from a wider uptake of fuel cell technology as it will “accelerate the introduction of hydrogen into the aviation domain”.
