A turbofan having a nacelle including a slider translationally mobile to open a window between a duct and the exterior, a plurality of blades, each rotationally mobile on the slider, and a maneuvering system moving each blade and comprising for each blade, a shaft rotationally mobile on the slider and onto which the blade is fixed, an arm having a first end fixed to the shaft, an arc coaxial with the longitudinal axis, mounted rotationally mobile on the slider about the longitudinal axis, a rectilinear rod fixed by its base to the arc, the rectilinear rod inserted into a through-bore of a stock, wherein the stock is mounted translationally free relative to the rectilinear rod, and the stock is mounted rotationally free on the arm at its second end about a rocking axis parallel to the rotational axis, and an actuation system producing arc rotation in two opposite directions.