The invention relates to an aircraft propulsion system (100) intended for being built into the rear of an aircraft fuselage, the propulsion system comprising at least two gas generators (102a, 102b) supplying a power turbine (104) having two counter-rotating turbine rotors (104a, 104b) for driving two fans (112a, 12b), and separate air inlets (106a, 106b) for supplying each gas generator, characterised in that it comprises an electrical drive device (140) configured to rotate at least one of the turbine rotors, at least one electrical generator (142a, 142b) configured to transform part of the energy of the flow from the gas generators into electrical power and an electric motor (146) supplied by said electrical generator and capable of rotating at least one of the turbine rotors, said electrical generator being installed on one of said gas generators, and in that said turbine rotor is capable of being rotated simultaneously by a flow from said gas generators and by the electrical drive device.