A BAe 146 flying testbed was to have one of its four Lycoming ALF502 turbofans replaced by a Siemens 2 MW (2,700 hp) electric motor, adapted by Rolls-Royce and powered by its AE2100 turboshaft, controlled and integrated by Airbus with a 2 t (4,400 lb) battery.

[2] At the 2018 Farnborough Airshow, Greg Clark, Business and Energy Secretary, announced the UK Department for BEIS will commit a part of the £255 million invested to develop greener flight technologies.

[3] At the June 2019 Paris Air Show, Rolls-Royce announced its acquisition of Siemens' electric propulsion branch, to be completed in late 2019, employing 180 in Germany and Hungary.

[4] On 19 August 2019, the compact 2.5 MW (3,400 hp) generator was run for the first time in Trondheim, Norway, before integration with an AE2100 turboprop from a Saab 2000 feeding the battery pack and a Siemens SP260D electric motor (with a 10 kW/kg power-to-weight ratio) replacing one Honeywell LF507 engine with a Rolls-Royce AE 3007 fan, through a 3,000 volts AC/DC distribution.

While Rolls-Royce is experienced in industrial and naval applications, the 2.5 MW (3,400 hp) generator feeding a 3,000 V DC distribution through its AC/DC converter are firsts in aviation.

Hybrid electric can offer improvements with present Battery Technologies : using them to boost power for takeoff and climb and electric-only descent would lower fuel burn per sector by double digits, and would reduce noise and local atmospheric emissions.