An autonomous propeller propulsion system for an aircraft. The autonomous system comprises a chassis with first attachment systems which engage with second attachment systems of the wing to ensure detachable attachment of the autonomous system, a fuel cell attached to the chassis, an electric motor attached to the chassis and having an output shaft, a propshaft rotated by the output shaft, a propeller attached to the propshaft, a controller converting an electric current delivered by the fuel cells into an electric current delivered to the electric motor, a hydrogen feed duct and an air feed duct, a set of auxiliary equipment, and a first connection arrangement, which connects with a second connection arrangement of the aircraft.