Ampaire yesterday announced plans to bring hybrid-electric power to more models of existing aircraft, including the Cessna 208B Grand Caravan and Viking Twin Otter; add a diesel-hybrid retrofit option for piston-powered aircraft; and begin airline demonstration runs without passengers later this year in Hawaii—with Mokulele Airlines on Maui—with its electric-hybrid Cessna 337 Skymaster conversion it calls the EEL.

Company CEO Kevin Noertker said his company’s engine conversions cut fuel consumption by between 70 and 90 percent, reduce maintenance expense by 20 to 50 percent, and produce significantly quieter aircraft. According to Noertker, Ampaire currently holds orders for 50 EELs, an overall order backlog valued at $70 million, contracts with the U.S. Air Force and NASA, and had received an investment from aircraft engine-maker Continental.

He said the market for bringing hybrid electric power to commuter aircraft could be worth more than $4 billion, noting that Norway has already set a goal of mandating all-electric flights on in-country flights of less than 90 minutes.