On April 10, 2010, about 1705 mountain standard time, a Cessna 210, N9527T, registered to Overseas Aircraft Support, Inc., Lakeside, Arizona, landed at the Show Low Regional Airport, Show Low, Arizona, with its landing gear intentionally retracted. The airplane was substantially damaged as it slid to a stop on the runway. Visual meteorological conditions prevailed at the time of the personal flight. No flight plan had been filed. Neither the private pilot nor passenger was injured. The flight was performed under the provisions of 14 Code of Federal Regulations Part 91, and it originated from Show Low about 1530. The pilot reported that, earlier during the day, maintenance had been performed to the airplane, which was manufactured in 1960. The maintenance did not involve the left main landing gear. According to the pilot, the accident occurred during the airplane's first flight following completion of maintenance to the nose wheel's shimmy dampner. The pilot stated that he planned to fly the airplane around the airport's traffic pattern to functionally check the maintenance. The pilot further reported that, during taxi and climb, no problems were noted with the airplane. However, when he attempted to extend the landing gear, the left main gear did not extend. The left gear remained in the wheel well, and the gear door was open. After troubleshooting the situation and following the emergency gear extension procedure, the pilot elected to land with all the gear in the retracted position. The airplane slid to a stop on runway 24. During recovery of the airplane off the runway, a mechanic reported observing that the left gear's brake line was caught on the gear leg snubber. The mechanic disconnected the brake line from the caliper and the landing gear extended without further difficulty. Interference between the brake line and the gear leg snubber had precluded the gear from extending. The Federal Aviation Administration (FAA) coordinator subsequently reported to the National Transportation Safety Board investigator that his examination of the airplane revealed its belly skin was abraded and a forward bulkhead, near the front door post area, was damaged. Repair to this bulkhead would require a major airframe structural repair. The FAA coordinator also reported that the left main landing gear's brake line was improperly positioned on the airplane. In the location where it was found on the accident flight, the line had inadequate clearance from the snubber and became hooked on it. This restricted the gear's movement out of the gear well. The FAA coordinator was unable to ascertain the underlying reason for the brake line not being properly attached to the gear leg in a manner that would provide adequate clearance from other objects.