The FAA Just Paid $2.9 Million to Learn How to Certify Hybrid Airliners

On October 12, the Federal Aviation Administration awarded Heart Aerospace $2.9 million to advance the megawatt-class turbogenerator at the center of its ES-36 regional aircraft propulsion system. The funding falls under Phase IV of the Continuous Lower Energy, Emissions, and Noise (CLEEN) program, and Heart will match the federal grant dollar for dollar, creating a $5.8 million, 24-month research and development effort designated Project HYPER, short for Hybrid Propulsion Environmental Readiness. (If you are catching up: the ES-36 is the 36-seat hybrid-electric airliner Heart unveiled on September 23, a two-nacelle redesign that replaced the ES-30 it had promoted since 2022.)

The $2.9 million figure is modest next to the $9 billion in customer commitments the company claims, but the money is the least interesting part of the announcement. What matters is the mechanism. The ES-36 is targeting FAA Part 25 certification, the standard for transport-category airliners, and there is no established playbook for certifying megawatt-scale hybrid-electric propulsion. Regulators historically certify technologies that already exist. Here, the technology and the rules have to be invented at the same time, and the FAA has decided the cheapest way to do that is to pay for the research and harvest the data.

What Project HYPER actually builds

The ES-36 is a series hybrid, which is worth explaining precisely because the term gets used loosely. Each of its two nacelles contains a 1.65-megawatt electric motor driving a propeller, and each motor has its own dedicated turbogenerator: a gas-turbine unit that makes electricity in flight to supplement the batteries. The turbogenerators never drive a propeller directly. On battery power alone the aircraft is designed to fly 125 miles; with the turbogenerators running, the targeted hybrid range extends to 745 miles including standard reserves.

Project HYPER funds the development and testing of those turbogenerators, and it is structured to end with demonstration flights of the hardware on the pre-production ES-36, which is scheduled for its first flight in 2028. The program builds on real flight hardware: on August 12, Heart flew its X1 demonstrator at Plattsburgh International Airport in New York, a 25,000-pound aircraft that stayed aloft for 27 minutes on battery power alone and reached 1,100 feet. The ES-36 itself exists so far as a production design unveiled on September 23, backed by a deposit-backed purchase agreement from regional carrier JSX for 50 aircraft with purchase rights for 50 more, and by what the company describes as more than $9 billion in customer commitments from carriers including United Airlines, Air Canada, and JSX. Entry into service is targeted for 2031.

The FAA is not simply funding a company research project. It is purchasing the data it needs to certify an aircraft category that does not yet exist.

A regulator buying its own homework

CLEEN Phase IV launched in September 2026 with two-year agreements awarded to several manufacturers, including Boeing, GE Aerospace, Honeywell Aerospace, and JetZero. Heart is not a one-time beneficiary: in September 2024 the FAA awarded the company a $4.1 million grant under the Fueling Aviation Sustainable Transition (FAST) program to support its Total Hybrid Electric Management and Integration System, or THEMIS. The pattern is consistent. The FAA keeps co-funding exactly the programs whose operational data it needs to write the compliance methods for series-hybrid architectures, which Heart Aerospace head of corporate affairs Cole Randle framed as advancing both the aircraft and the broader industry understanding of how to build, test, and certify hybrid-electric aircraft.

There is a defensible logic here. Part 25 was written for kerosene-burning tube-and-wing aircraft, and adapting it to a series hybrid where the energy path runs from turbine to generator to motor to propeller requires evidence about failure modes that no one has yet observed in service. Rather than wait for a certification application to expose the gaps, the regulator is front-running the problem. The risk, of course, is optics: a regulator that pays a company to generate the data it will then judge can look captured. The counterargument is that CLEEN is explicitly a public-private partnership and the knowledge is meant to generalize across the regional hybrid sector, not to sit in Heart proprietary vaults.

Why this matters beyond Heart

If the ES-36 enters service in 2031 as planned, it would be the first electric-propulsion airliner in scheduled service, and the range numbers explain why regional carriers care. A 125-mile all-electric leg covers a meaningful share of short regional hops, while the 745-mile hybrid envelope reaches deep into the routes that turboprops fly today, with fuel burn and emissions that Heart claims will be substantially lower than conventional equivalents. The 1,415-pound payload increase over the ES-30 and the six extra seats are the kind of incremental economics that decide whether a regional operator actually converts an order into a fleet.

The more structural point is about standards. Whoever produces the first credible megawatt-class hybrid certification data set effectively sets the template for everyone who follows, including programs like JetZero that are also inside the CLEEN tent. Heart Aerospace chief technology officer Ben Stabler said the FAA partnership will accelerate development of the hybrid-electric powertrain, but the sentence that matters most may belong to the regulator, not the company. The FAA has confirmed, by writing checks two years running, that it intends to learn this technology by co-owning it. That makes Project HYPER a small bet with a large shadow: a $5.8 million program whose data could shape the certification basis for an entire generation of hybrid airliners.