H55 has announced completion of the aviation industry’s first regulator-required and authority-witnessed propulsion battery module certification test sequence, addressing a key technical barrier in the certification of electric aircraft propulsion systems.

 

The milestone was achieved following an EASA-supervised campaign completed on 19 December 2025, with the results providing certification-level evidence that commercial lithium battery cells can be integrated into propulsion battery systems capable of safely containing worst-case failure scenarios, including fire propagation. The company states the campaign establishes a reference standard for future electric aviation battery certification programmes.

 

Electric aviation development has faced a major challenge in demonstrating to regulators that high-energy propulsion batteries can safely contain critical failure events. The completion of this test campaign represents a step toward enabling certification and commercial deployment of electric propulsion technologies.

 

The campaign was conducted using serial-conforming hardware manufactured in a certified production facility using validated manufacturing processes. According to H55, the tests confirm the company’s ability to design and manufacture propulsion battery systems to certification standards on regulatory-approved manufacturing lines and supply chains.

H55’s Energy Storage System design incorporates monitoring, redundancy and hazard mitigation at cell level. The company states this architecture is designed to ensure containment of extreme failure conditions in line with aviation safety requirements.

 

The company says the milestone establishes a repeatable certification pathway for its battery technology, supporting deployment across multiple aircraft programmes rather than a single platform. H55 states that certification-grade reference frameworks reduce adoption risk for manufacturers, operators, insurers and investors by enabling actuarial risk assessment based on authority-validated data.

 

The propulsion battery system is now positioned to support development of both fully electric and hybrid-electric aircraft. H55 states that data and certification evidence generated through the campaign support several programmes, including the BRM B23 Energic, CAE electric training platform development and the hybrid-electric Dash 8 demonstration programme with Pratt & Whitney Canada.

 

H55 reports more than 20 years of electric aviation experience, including development and operation of six electric aircraft and more than 2,000 hours of fully electric flight operations with no battery-related incidents.

 

André Borschberg, Executive Chairman and Co-Founder of H55, said the company was established to enable certification of electric aviation systems through alignment with aviation safety standards and performance optimisation. He said the milestone demonstrates that electric propulsion systems can be engineered to meet certification and safety expectations consistent with conventional aircraft.

 

Rob Solomon, Chief Executive Officer of H55, described the achievement as a structural step forward for electric aviation, stating that completion of the EASA-agreed battery module test campaign addresses a key certification bottleneck and reduces risk across the electric aviation value chain. He added that the system enables cell-level monitoring and protection, supporting both regulatory certification and fleet insurability. Solomon also noted that EASA and the U.S. Federal Aviation Administration are working through a joint Certification Management Team, with test results expected to support H55’s certification activities in the United States.

 

Sébastien Aymon-Demont, Co-Founder and Chief Technology Officer of H55, said the system architecture is based on protection, monitoring and mitigation at cell level rather than pack-level assumptions, supporting safety performance, efficiency and long-term reliability.

 

The test campaign included more than 100 test articles produced from approved product configurations. The six-month programme evaluated environmental, safety, functional and performance characteristics under worst-case failure scenarios, including authority-witnessed thermal runaway testing without propagation. H55 plans to submit final test documentation to EASA for formal acceptance during the first quarter of 2026.

 

H55 holds both EASA Design Organisation Approval and Production Organisation Approval for electric propulsion systems, confirming certification capability and validated production and quality systems for aerospace products.

 

The company states that completion of propulsion battery module certification testing reduces a major barrier to electric aviation commercialisation by enabling repeatable certification and deployment across aircraft programmes. The company says this supports scalable industrialisation and reduces regulatory and insurance risk exposure across electric aircraft fleets.

 

H55 is a Swiss company specialising in certified electric propulsion and certification-grade energy storage systems. The company focuses on converting commercial lithium cells into aviation-certified energy storage systems through cell characterisation, screening processes, redundant safety architecture and regulator-aligned testing. H55 was founded as part of the technological legacy of the Solar Impulse programme and continues to focus on electric aviation industrialisation and certification-driven deployment.