H2FLY announced that it has successfully completed liquid H₂ on-ground coupling tests with its HY4 aircraft for the first time. This achievement is part of the European project HEAVEN, a consortium of six companies to demonstrate the feasibility of using liquid, cryogenic H₂ in aircraft, led by H2FLY. The new liquid H₂ storage system, which is designed and supplied by Air Liquide based on H2FLY’s requirements, has been successfully coupled with the fuel cell system on ground.

This coupling represents the final technological building block in the development of a complete H₂-electric powertrain using liquid H₂ to power the HY4—H2FLY’s four-seater demonstrator aircraft which runs on H₂ and fuel cells producing zero-emissions and demonstrating the feasibility of H₂-electric propulsion systems for aircraft. The company led the test campaign on Air Liquide’s Campus Technologies Grenoble, in Sassenage, France together with Air Liquide.

The successful coupling tests mark another important step toward the upcoming ground and flight test campaign this summer when the HY4 is expected to be the first passenger aircraft to fly with liquid H₂ and fuel cells. H2FLY is the first company to successfully perform on-ground coupling tests with an aircraft-integrated LH₂ tank and fuel cell system proving its pioneering technological advancements with fuel cell systems, H₂ storage systems and H₂ fuel system design for CS-23 and CS-25 aircraft. CS-23 and CS-25 are regulations established by the European Aviation Safety Agency ensuring that aircraft meet the necessary standards for certification.

Furthermore, the company has established specialist knowledge when handling liquid H₂ as it worked together with Air Liquide to develop new safety concepts in preparation for the coupling tests.

Prof. Dr. Josef Kallo, co-founder and CEO of H2FLY said, “With the successful passing of the on-ground coupling tests, we have learnt that it will be possible to also scale up our technology for a 40-seater aircraft. We are thrilled to be making this crucial progress as we continue our efforts towards making sustainable medium and long-haul flight a reality.”