On September 30, 2007, about 1515 Pacific daylight time, a Piper PA-32R-301T, N4175A, landed with retracted landing gear at the Stockton Metropolitan Airport, Stockton, California, following a hard landing at another airport. The airplane was registered to N4175, LLC, and it was operated by the company's owner on a personal flight. The airplane was substantially damaged, and neither the private pilot nor passenger was injured. Visual meteorological conditions prevailed at the time, and no flight plan had been filed. The flight was performed under the provisions of 14 CFR Part 91, and it originated from San Carlos, California, about 1330. In pertinent part, the pilot reported to the National Transportation Safety Board investigator that his planned destination was the Pine Mountain Lake (uncontrolled) Airport, Groveland, California. He had landed at Pine Mountain during the past 4 to 6 years, and he was familiar with the runway environment. Pine Mountain's runway 09/27 is 3,625 feet long and 50 feet wide. The runway has an asphalt surface. The pilot reported that the flight to Pine Mountain was uneventful. During his approach to runway 27 he noted that the wind was from the south, so he placed the airplane into a crab on the final approach leg. The pilot reported that nearing the runway and "just before coming over the threshold" about 20 feet above the ground, "there was a sudden downdraft and the plane rapidly and suddenly sunk toward the ground." The right main landing gear impacted the gravel and dirt area about 10 feet in front and to the right of the runway. The pilot aborted the landing and performed a go-around. Ground-based witnesses observed the mishap and informed the pilot that the airplane's landing gear appeared damaged. The pilot diverted to Stockton where he made an intentional gear up landing. The airplane was examined by Federal Aviation Administration personnel following its removal from Stockton's runway. The right main landing gear was found broken, structural components in the right wing were found deformed, and the right side of the fuselage was buckled at the bulkhead aft of the wing-to-fuselage attachment point.