Abstract: The engine is of the type having a central body surrounded by a casing defining therebetween a duct for the passage of the flux. The casing comprises a fixed upstream section extended downstream by means in which are housed jacks; a downstream section movable axially to which are fixed the rods of the jacks; and an intermediate section formed of swinging doors mounted between the beams and hinged thereto by lateral pivots, each door being coupled to the mobile downstream section by means of a hinged link so that the movement of the downstream section causes the doors to swing. This type of reverser is designed more especially for turbo-fan engines having a lateral nacelle configuration in which the whole of the flux flows in the annular duct between the central body and the casing.