12-Hour Hybrid-Electric Flight Sets New Endurance Record

Ampaire is the maker of the nine-seat Eco Caravan, which it claims to be the world’s largest hybrid-electric airplane. This week, the company announced it flew its Electric EEL demonstrator on a 12-hour, 1,375 sm (1,195 nm) jaunt out of Camarillo Airport (KCMA) in California—a feat it believes establishes an endurance record for hybrid-electric aircraft.

The firm said the demonstrator touched down with more than two hours of battery and fuel reserves remaining.

“Through this groundbreaking mission, Ampaire has shattered the conventional boundaries of electrified flight, underscoring our relentless pursuit of transformative vehicle performance and commercial utility,” said Ampaire CEO Kevin Noertker. “Our unique hybrid-electric solutions deliver unparalleled operating economics and unlock endurance and operational flexibility critical to our customer's needs.”

The flight, which took place Sunday, comes just 17 months after a then-record 1,135 sm flight of the EEL from Camarillo to Wittman Regional Airport (KOSH) in Oshkosh, Wisconsin, which was validated by the International Air Transport Association (IATA).

Another manufacturer, Electra.aero, last month completed what it’s calling the “world’s first” flight of a hybrid-electric short takeoff and landing (STOL) design.

Ampaire’s EEL is a modified Cessna 337 Skymaster equipped with the company’s proprietary AMP-H570 AMP Drive: a hybrid-electric propulsion unit that’s also flying on its flagship Eco Caravan. The EEL is primarily a testbed aircraft, but the company says it can also serve owner-flown, charter, and short-haul regional airlines and carriers. The design boasts a 400 sm (348 nm) range and 450-pound payload capacity.

According to Ampaire, the EEL offers a larger payload than all-electric or all-hydrogen designs while enabling quicker infrastructure and certification timelines. It produces more emissions than all-electric models, but the manufacturer found that it achieved a 50 to 70 percent reduction in fuel consumption and emissions compared to traditional Pratt & Whitney PT6 turboprop engines.

Ampaire described Sunday’s flight as the “crowning achievement” for the EEL. The demonstrator, the company’s second hybrid-electric prototype, first flew in 2020. Since then, it’s visited California, Arizona, Hawaii, Alaska, and Canada, often crossing state lines—and occasionally international borders—while picking up records and aviation firsts along the way.

The EEL’s first cross-country test flight between Camarillo Airport and Hayward Executive Airport (KHWD) came in 2020. Ampaire claimed the 2.5-hour, 341 sm (296 nm) trip was “the longest flight to date for any commercially relevant aircraft employing electric propulsion.”

Just a few months later, Ampaire partnered with Hawaii’s Mokulele Airlines to achieve another aviation milestone: the first trial of a hybrid-electric aircraft along an actual airline route. The project aims to demonstrate the island-hopping value of electric aviation. Not long after, the EEL made its debut in the U.K. hopping between Scotland’s Orkney Isles.

Then came 2022’s record-setting flight: a 1,135 sm (986 nm) jaunt from Camarillo to Oshkosh. But the company didn’t stop there.

In August, Ampaire flew the EEL to Alaska, which it said represented several firsts: the first hybrid-electric aircraft deployment in Alaska, first international hybrid-electric flight, and first aircraft to obtain special airworthiness approvals from regulators in both the U.S. and Canada. In November, it made the inaugural hybrid-electric flight into Palo Alto Airport (KPAO).

While the EEL is garnering headlines for its record-breaking demonstrations, Ampaire’s flagship Eco Caravan is flying too. The model is a modified Cessna 208B Grand Caravan with a 1,100 sm (956 nm) range and 2,500-pound payload. Last year, the company said it could be the first electrified regional aircraft to enter commercial service, with FAA certification expected in 2024.

Ampaire’s largest order for the Eco Caravan came in 2022 from U.K.-based lessor Monte Aircraft, which agreed to order up to 50 models. It also signed a deal with Azul Conecta, a subsidiary of Brazil’s largest airline by passenger volume, to convert six Grand Caravans in its fleet.

Behind the scenes, Ampaire has been working with NASA on several projects, most notably a collaboration to equip its propulsion system on its largest aircraft yet: a Twin Otter DHC6. It has an agreement with private charter operator WingTips for the conversion of 50 Twin Otters to Eco Otters—another Ampaire concept—in addition to 20 Caravans.

Like this story? We think you'll also like the Future of FLYING newsletter sent every Thursday afternoon. Sign up now.