CA2867082A1 CA2867082A CA2867082A CA2867082A1 CA 2867082 A1 CA2867082 A1 CA 2867082A1 CA 2867082 A CA2867082 A CA 2867082A CA 2867082 A CA2867082 A CA 2867082A CA 2867082 A1 CA2867082 A1 CA 2867082A1 Authority CA Canada Prior art keywords flange frame part concave section facing surface topshell Prior art date …