At BHL FTS we had several mild steel discs painted red and staked down near the grass runway at Redhill. Pilots doing engine off's used to aim for the disc's, which was fine in the 47 as the skids just rode over them. A R22 tried this and the little ground pads under the skids caught under the steel disc resulting in a nasty accident. IIRC the cabin separated from the skids, no one hurt. I am impressed with the strength of the 22 cabin.