FAA Selects Heart Aerospace for $2.9 Million CLEEN Award to Advance ES-36 Hybrid Propulsion System

The award will fund Heart’s Project HYPER (Hybrid Propulsion Environmental Readiness), which will advance development and testing of a Heart turbogenerator for the ES-36’s series-hybrid propulsion system. Each of the aircraft’s two propulsion nacelles will house a megawatt-class turbogenerator that produces electricity in flight, extending the ES-36’s range beyond what batteries alone can provide.

Through Project HYPER, Heart will develop and test the ES-36 turbogenerator on the company’s pre-production aircraft, scheduled to make its first flight in 2028. The project will begin with ground testing to evaluate how the turbogenerator, batteries and electric motors work together in different operating modes, before progressing to demonstration flights aboard the pre-production ES-36. The project will generate data on energy use, fuel burn, emissions, and noise to support ES-36 certification and inform the FAA’s approach to evaluating and certifying hybrid-electric aircraft more broadly.

“The FAA’s continued partnership with Heart Aerospace will accelerate development of this key element of the ES-36’s disruptive hybrid-electric powertrain,” said Ben Stabler, Chief Technology Officer of Heart Aerospace. “Together, we are advancing technologies that will help bring to market a new generation of commercial aircraft that use less fuel, produce fewer emissions and make less noise, benefiting passengers, operators and the communities they serve.”

The CLEEN award extends FAA support for the development of Heart’s hybrid-electric powertrain, initially provided through the agency’s Fueling Aviation’s Sustainable Transition (FAST) program. That funding supported development of Heart’s Total Hybrid Electric Management and Integration System (THEMIS), the propulsion control architecture that coordinates the ES-36’s electric motors, turbogenerators and batteries during flight.

Together, the turbogenerators and THEMIS will enable ES-36 to fly on battery power alone for short-haul routes and will supplement battery power with electricity generated from Jet A and sustainable aviation fuel (SAF) for longer regional missions. Heart is targeting an ES-36 all-electric range of 125 miles and a hybrid range of up to 745 miles, both plus reserves.

“We’re grateful to the FAA for the agency’s continued investment in Heart’s hybrid-electric powertrain and the technologies needed to bring electric aviation to commercial scale,” said Cole Randle, Head of Corporate Affairs at Heart Aerospace. “Through CLEEN, Heart will advance the ES-36 toward flight demonstration while generating knowledge that can help the broader industry understand how to build, test, and certify hybrid-electric aircraft.”

The award adds to a series of milestones for Heart in 2026, including the first flight of the company’s X1 demonstrator aircraft, the unveiling of the 36-seat ES-36 production aircraft, and a purchase agreement with JSX for up to 100 ES-36 aircraft.

About Heart Aerospace

Heart Aerospace is a Los Angeles-based electric aircraft manufacturer on a mission to lower the cost of air travel. In August 2026, Heart flew the company’s X1 demonstrator, the world’s largest battery-electric aircraft, advancing electric flight into the airliner category. The company’s first production aircraft, the Heart ES-36, is a clean-sheet, 36-seat hybrid-electric regional aircraft designed to bring cost-efficient electric flight into everyday airline service. Backed by over $9 billion in customer commitments from leading carriers including United Airlines, Air Canada, and JSX, Heart is advancing technologies to make electric aviation work at commercial scale. Learn more about Heart and the company’s vision for abundant, affordable air travel at www.heartaerospace.com.

Media Contact

Cole Randle
Head of Corporate Affairs
press@heartaerospace.com
+1-310-561-5193

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