Turbofan engine comprising an engine and a nacelle surrounding the engine and in which a bypass duct of a bypass stream is delimited between the nacelle and the engine, said nacelle comprising: - a fan casing comprising an outer wall, - a fixed assembly comprising a fixed structure and secured to the fan casing, - a movable assembly comprising a movable structure to which are fixed a movable cowl and a frame with holed zones forward of the movable cowl, the movable structure being translationally movable on the fixed structure in a direction of translation between an advanced position in which the movable structure is positioned such that the movable cowl is moved close to and extends the outer wall, and a retracted position in which the movable structure is positioned such that the movable cowl is separated aft from the outer wall so as to open a window between the bypass duct and the outside of the nacelle, in which the holed zones are positioned across the window in the retracted position, - a plurality of blocking doors, in which each is movably mounted on the movable structure between a stowed position in which the blocking door is out of the bypass duct and a deployed position in which the blocking door extends across the bypass duct, - a set of cylinders provided to ensure the translational displacement of the movable structure from the advanced position to the retracted position and vice versa, in which the retracted position corresponds to a stopping of the cylinders, - at least one cascade grid mounted on the frame and disposed across the holed zone, characterized in that the or each cascade grid is slidingly mounted on the frame parallel to the direction of translation, and in that the turbofan engine also comprises - for each cascade grid, at least one forward stop limiting the displacement of said cascade grid forwards and at least one rear stop limiting the displacement of said cascade grid rearwards, - for each cascade grid, at least one compression spring which pushes the cascade grid rearwards for it to stop against a rear stop, and - for each cascade grid, the fixed structure comprises at least one stop element against which the cascade grid comes into abutment upon the displacement from the advanced position to the retracted position, and in which the or each stop element is arranged to guarantee a functional play between the cascade grid and the associated front stop even when the movable structure reaches the retracted position. - a fan casing comprising an outer wall, - a fixed assembly comprising a fixed structure and secured to the fan casing, - a movable assembly comprising a movable structure to which are fixed a movable cowl and a frame with holed zones forward of the movable cowl, the movable structure being translationally movable on the fixed structure in a direction of translation between an advanced position in which the movable structure is positioned such that the movable cowl is moved close to and extends the outer wall, and a retracted position in which the movable structure is positioned such that the movable cowl is separated aft from the outer wall so as to open a window between the bypass duct and the outside of the nacelle, in which the holed zones are positioned across the window in the retracted position, - a plurality of blocking doors, in which each is movably mounted on the movable structure between a stowed position in which the blocking door is out of the bypass duct and a deployed position in which the blocking door extends across the bypass duct, - a set of cylinders provided to ensure the translational displacement of the movable structure from the advanced position to the retracted position and vice versa, in which the retracted position corresponds to a stopping of the cylinders, - at least one cascade grid mounted on the frame and disposed across the holed zone, characterized in that the or each cascade grid is slidingly mounted on the frame parallel to the direction of translation, and in that the turbofan engine also comprises - for each cascade grid, at least one forward stop limiting the displacement of said cascade grid forwards and at least one rear stop limiting the displacement of said cascade grid rearwards, - for each cascade grid, at least one compression spring which pushes the cascade grid rearwards for it to stop against a rear stop, and - for each cascade grid, the fixed structure comprises at least one stop element against which the cascade grid comes into abutment upon the displacement from the advanced position to the retracted position, and in which the or each stop element is arranged to guarantee a functional play between the cascade grid and the associated front stop even when the movable structure reaches the retracted position.