This article is based on the project EFACA (Environmentally Friendly Aviation tor All Classes of Aircraft) that is supported by the European Union in the period 2023-2026. The study is based on the idea that the image of a hybrid turbine-electric system with "fuel cells" for a regional aircraft with a capacity of up to 80 seats and a range of up to 1000 km will be determined by the type of energy supply (hydrocarbon or hydrogen fuel) to the gas turbine and electric engines. The use of a sequential approach to the definition of the HTEP design includes the initial definition of the top-level requirements for the HTEP and the aircraft, the evaluation of conceptual schemes for the HTEP power supply, the preliminary formation of HTEP component designs, the further development of fuel supply, storage, fuel conditioning, and power distribution and manage systems. In the next step, according to the selected evaluation criteria, the optimal scheme will be determined to provide energy to the HTEEP with fuel cells. Taking into account the influence of the level of hybridisation of the propulsion system on its configuration, as well as a comparison of the hybrid-electric aircraft with its existing analogue (ATR 72), a more accurate assessment of the performance of the regional aircraft will be made. The performance of the propulsion concept, which consists of an air propeller driven by a gearbox combining turbine and electric motor drives, will be assessed in the first TRL3 level demonstration bench test.