Four incidents of Citation VII main gear collapses during landing have prompted a proposed AD calling for operators to check for a possible wrong part. If the AD is adopted, the FAA would give affected operators six months to conduct a one-time inspection of the side-brace mechanism to detect the incorrect part. A mechanism found with the incorrect part number would have to be replaced with the correct part. The FAA estimates that 282 airplanes of U.S. registry would be affected by the AD.