The forward piston engine of a Cessna 337 Skymaster (a push-pull aircraft) is replaced by an electric motor powered by a battery, in a parallel hybrid configuration.

[1] Later that month, Personal Airline Exchange (PAX) became the launch customer for the electric EEL modified six-seat Skymaster, to be certified in 2021, with an order for 50 plus 50 options.

[6] US start-up PAX is an on-demand per-seat charter offering point-to-point service competing with driving, is connecting small airports to bypass hubs and congested roads.

PAX will acquire two Cessna 337s, sourced and refurbished by Ampaire, to start commercial operations in early 2020 in southern California before a nationwide introduction, with their original engines.

[11] On 10 December 2023, Ampaire flew the Electric EEL for 12h, covering 1,195nm (2,213km) from Camarillo Airport in California, limited by remaining daylight hours and landing with 2h left of fuel and battery reserve.