A propulsive system for an aircraft including an auxiliary jet engine is integrated into a tail cone of a fuselage. A carrying structure of the jet engine is primarily formed with beams and frames or half-frames to which the auxiliary jet engine is fixed by lateral beams. The beams are interdependent of the frames and half-frames, and the beams are overhanging behind a frame behind which is fixed the engine. Each beam includes a lower half-beam and a higher half-beam, separated on at least a part of its length ahead from attachments of the jet engine to determine a space free of structure impediment for lateral air intakes.