On July 27, 2001 about 1851 Pacific daylight time, a Williams RV-6A, N131LH, owned and operated by the pilot, made a hard landing on runway 25 at the Jack Northrop Field, Hawthorne, California. The experimental airplane was substantially damaged. Neither the certificated airline transport pilot nor the passenger was injured. Visual meteorological conditions prevailed during the personal flight. No flight plan was filed. The flight was performed under 14 CFR Part 91, and it originated from Alamosa, Colorado, about 1230 mountain daylight time. The pilot verbally reported to the National Transportation Safety Board investigator that he had to add engine power during the landing flare. However, the airplane likely stalled and "dropped hard" onto the runway. The left wing broke. In the pilot's completed accident report, he indicated that he had landed long because the airplane's hangar was at the far end of runway 25. During the landing flare a windshear or gust lifted the right wing upward, and the left wing tip contacted the runway. He attempted to increase engine power to compensate for the upset, but he was not successful. At 1853, Hawthorne reported its surface wind was from 250 degrees at 7 knots. No gusts were reported. The (great circle) distance between Alamosa and Hawthorne is about 643 nautical miles. The pilot was unclear regarding his exact departure time. However, he stated that the flight was performed nonstop.