Electric aviation has faced a single, unresolved bottleneck: proving to regulators that high-energy propulsion batteries can safely contain worst-case failures.

H55 today announces that it has completed the industry's first regulator-required and authority-witnessed propulsion battery module certification test sequence — addressing a critical gating factor that has constrained the commercialisation and financing of electric aircraft programs.

Completed on December 19, 2025, the EASA-supervised campaign places H55 at the forefront of efforts to establish certification-grade, aviation-safe propulsion battery systems, setting the standards against which future programs will be assessed. The campaign provides certification-level evidence that commercial lithium battery cells can be integrated into aviation propulsion battery systems capable of safely containing worst-case failure scenarios, especially fire propagation.

From Validation to Scalable Certification

This milestone goes beyond documenting or promising safety performance. It confirms H55's ability to engineer and manufacture propulsion battery systems developed to certification standards on regulatory-approved manufacturing lines and supply chains.

The test campaign was conducted in a certified production facility using serial-conforming hardware (not prototypes) manufactured through validated processes. It confirms H55's ability to engineer and manufacture propulsion battery systems built to certification standards on regulatory-approved manufacturing lines and supply chains.

H55's unique, patented Energy Storage System design embeds monitoring, redundancy, and hazard mitigation at the cell level as foundational principles, ensuring containment of extreme failure conditions consistent with aviation safety requirements.

This approach establishes a repeatable certification pathway for H55's battery technology, rather than advancing a single aircraft programme. By defining a certification-grade battery module reference framework, H55 materially reduces adoption risk for aircraft manufacturers, operators, insurers, and investors by enabling actuarial risk assessment based on authority-validated failure data rather than programme-specific assumptions. With certification evidence able to compound across a wide range of aircraft platforms, capital, engineering resources, and industrial capacity can expand without proportional increases in programme-level uncertainty.

The system foundations established through H55's first conforming propulsion battery system now support accelerated development and regulatory progress for both fully electric and hybrid-electric aircraft. The data, infrastructure, and certification-standard evidence produced through this campaign underpin multiple ongoing customer programmes, including the BRM B23 Energic, CAE's transition toward all-electric pilot training platforms, and the hybrid-electric Dash 8 demonstration programme with Pratt & Whitney Canada.

With more than 20 years of electric aviation experience, six electric aircraft designed, built, and flown, and over 2,000 fully electric flight hours accumulated with zero battery-related incidents, H55 brings the operational depth required to execute certification-grade programmes — not merely comply with them.

André Borschberg, Executive Chairman and Co-Founder of H55, said:

"H55 was created with a single objective: to make electric aviation certifiable, not just possible. From the outset, that meant designing systems around aviation safety standards and preventing failure while optimising performance.

This milestone validates that choice. Electric aviation can be engineered to meet the same certification discipline and safety expectations as conventional aircraft. At H55, disciplined, focused ambition is what translates certification into real market adoption and scalable commercial impact."

Rob Solomon, Chief Executive Officer of H55, added:

"This achievement marks a structural inflection point for electric aviation. By completing the first EASA-agreed battery module test campaign, H55 has addressed the most critical technical bottleneck on the certification path, materially reducing risk for aircraft manufacturers, operators, insurers, and investors.

By providing monitoring, active and passive protections of every individual cell, H55 transforms the propulsion battery from a 'black box' of latent risk into an actuarially transparent asset, establishing cell-level monitoring as the non-negotiable threshold for both regulatory type certification and fleet insurability. What's most exciting, is the engine-like business model this enables for H55.

In parallel, through a joint multi-authority Certification Management Team, EASA and the U.S. Federal Aviation Administration (FAA) have committed to mutual recognition of agreed means of compliance for ongoing programs. Test results will be transferred to the FAA, providing a basis for supporting and accelerating H55's U.S. certification activities and market presence."

Sébastien Aymon-Demont, Co-Founder and Chief Technology Officer of H55, commented on battery module architecture and the cell level approach,

"By designing protection, monitoring, and mitigation directly at cell level, rather than relying on pack-level assumptions, we have built a fundamentally different Energy Storage System. This cell-level architecture not only enables effective protection at the point of origin, but also allows us to optimise battery efficiency, performance, and long-term reliability — all of which are essential for certifiable electric aviation."

About the Test Campaign

To execute this campaign, H55 produced more than 100 test articles drawn from its approved and audited product configuration. The six-month effort covered environmental, safety, functional, and performance conditions under worst-case failure modes, including authority-witnessed thermal runaway tests without propagation. Collectively, these results confirm readiness for certification and industrial deployment, including:

- Completion of the certification campaign for propulsion battery modules

- Confirmation that H55 remains the only organisation holding both EASA Design Organisation Approval (DOA) and Production Organisation Approval (POA) for electric propulsion systems

- Production of series-manufacturing-conforming propulsion battery modules

- Completion of the first EASA-validated cell characterisation campaign for certified propulsion battery systems

- The safety demonstrated during testing completed in December 2025 is now being documented into final test reports, which H55 is submitting to EASA for formal acceptance in Q1 2026

Clearing the Certification Bottleneck to Enable Scalable Commercialisation

Electric aviation scales on certification. By completing this regulator-approved propulsion battery module test campaign, H55 has materially reduced the primary constraint that determines which electric aviation technologies can commercialise. Formal demonstration of containment under worst-case failure scenarios materially reduces regulatory and insurance exposure, unlocking repeatable, certifiable deployment across aircraft programs while ensuring aircraft-level safety.

With this achievement, H55 is transitioning from validation to scale. A single, certifiable Energy Storage System architecture can now be deployed across multiple platforms, allowing certification evidence to compound as revenue potential expands without proportional increases in development cost, supporting repeatable deployment across fleets and aircraft lifecycles rather than one-off programme deliveries. With propulsion battery-module certification risk now addressed, electric aviation moves from speculative development to a certifiable industrial category — reshaping how programs are evaluated, financed, and insured.