A combine harvester including a frame and a twin rotor crop processor mounted to the frame. The processor comprises a pair of axial-flow crop processing rotors arranged side-by-side and each being mounted for rotation inside a generally cylindrical rotor housing. Each rotor housing includes a curved cover plate. Each cover plate has a structure that includes a flange along a longitudinal edge for securing the plate to a central frame member between the rotor housings. Both flanges intersect a hypothetical vertical plane aligned with the frame member.
