A project to convert the nine-passenger Britten-Norman Islander to hybrid-electric propulsion for short-haul flights has kicked off in the UK. Project Fresson is led by Cranfield Aerospace Solutions (CAeS), which plans to obtain and market a supplemental type certificate (STC) for the conversion.

CAeS is leading a UK team that includes the aircraft’s manufacturer, Britten-Norman; Rolls-Royce, providing the power management system; the Denis Ferranti Group, supplying electric motors; Delta Motorsport, the battery pack; and Warwick Manufacturing Group, performing battery testing.

CAeS parent Cranfield University is also involved, as is Islander operator Loganair, which is expected to be the first customer for the electric propulsion conversion, for use on its short inter-island services in the Orkneys, off the northeast coast of Scotland.

Phase 1 of Project Fresson kicked off Oct. 1 and is a 30-month effort intended to culminate in flight of a demonstrator aircraft. This is planned to be as close to production standard as possible, CAeS CEO Paul Hutton said, so that a European Aviation Safety Agency (EASA) STC can then be obtained within another 6-12 months.

In addition to two electric motors replacing the Islander’s twin piston or turbine engines, the conversion includes a range-extender combustion engine to recharge the batteries in flight. The hybrid-electric Islander will have a flight duration of 60 min., plus 30 min. reserves, Hutton said.

Energy costs—electricity and fuel for the range extender—are projected to be less than 20% of the cost of aviation gasoline to power the existing piston-powered Islander, he said. “An operator will typically recover the cost of the conversion in three years through electricity costs and reduced maintenance.”

The £18 million ($22 million) first phase of Project Fresson is expected to be supported by UK government funding provided via the Aerospace Technology Institute. This will cover 50% of the project’s cost, with the rest of the funds to be provided by the partners, Hutton said.

CAeS will own the STC and sell the electric-propulsion conversion into the Islander market. There are about 800 aircraft in service and Britten-Norman estimates about three-quarters of those, some 600 Islanders, are used for short-haul flights and therefore suitable for conversion, he says.

“Converting a well-proven aircraft under an EASA STC is the quickest way to get to passenger services [with electric aircraft],” Hutton said. And the short hops flown by Islanders are the best application, “because we are not challenging the [battery] technology too greatly.”

In addition, the Islander is used for short-duration flights in areas where there is a lot of renewable energy available, Hutton said. These include the Highlands and Islands region of Scotland and countries such as Norway, which aims for all domestic flights to be 100% electric by 2040.

Named after Scottish pioneer aviator Ted Fresson, the project is intended to have two more phases, if funding can be raised. In Phase 2, CAeS plans to convert an existing 19-seat aircraft to hybrid-electric propulsion. In Phase 3, that EASA-certified power train would be used in a new-design 19-seat airliner.

“We think the sub-regional market is the most credible to be converted to hybrid-electric,” Hutton said. As fuel prices increased, regional airliners got bigger, leaving the 9-19-seat market essentially unserved. “But with the move to electric, the cost of energy is a fraction that of fuel, so that economic model has to be challenged and sub-regional aircraft will become attractive again,” he said.

Developing and marketing an STC for an aircraft conversion is a new venture for CAeS, which previously has done one-off modifications. Fresson is its second electric-aircraft project. The company is working with UK carmaker UK Aston Martin on the Volante Vision electric vertical-takeoff-and-landing concept. “We are moving on from the concept and hope to launch in the next six months,” Hutton said.

Graham Warwick Graham.warwick@aviationweek.com