Electric aircraft developer Ampaire and services provider Ikhana Aircraft Services have joined forces to study the feasibility of equipping de Havilland Canada DHC-6 Twin Otters with hybrid electric propulsion.
The companies, which already work together to equip Cessna 337 Skymasters with hybrid-electric systems, are now moving further along the hybrid-electric path.
The Twin Otter study comes after Ampaire won a contract from NASA, which is seeking to advance electric technology as part of its Electric Aircraft Propulsion programme.
Ampaire enlisted help from Ikhana, which specialises in aircraft modifications, engineering and certification work. Ikhana performs life-extensions on Twin Otters and holds a supplemental type certificates to increase Twin Otter maximum takeoff weights from 5,443kg (12,000lb) to 6,350kg. That increase could prove valuable for carrying heavy batteries, says Ikhana chief executive John Zublin.
He calls Twin Otters "perfect aircraft" for hybrid-electric modifications because they carry enough passengers – 19 – to make such technology economically feasible.
"There is so much rumbling going on in the world of electric aircraft – it is something that is going to get there," Zublin says.
Ampaire envisions Twin Otters with hybrid propulsion combining a diesel engine and an electric system, says Ampaire product manager Brice Nzeukou.
The companies expect to complete their study by the end of the year.
Ampaire flew an electric-and-gas-powered Cessna 337 Skymaster this year. With assistance from Ikhana, Ampaire replaced the 337's rear engine (which drives a pusher prop) with an electric propulsion system, leaving the forward engine in place.
It is now swapping the configuration around – putting the engine in the back and moving the electric system forward, with batteries removed from the cabin and installed in a pod under the aircraft.
Ampaire's partner on the 337, Hawaii-based Mokulele Airlines, will fly the aircraft in this new configuration in the first quarter of next year, says Nzeukou.
Ampaire hopes to have the modified 337 certificated by the end of 2021.
The 337 and Twin Otter programmes will help develop technology that could eventually apply to a small airliner like a De Havilland Aircraft Canada Dash 8 in the 2030-2035 timeframe, Nzeukou says.
"When you are dealing with powerplants, it takes a while," says Zublin. "Ampaire is going about this in the right way."