On May 13, 2000, about 1430 Alaska daylight time, a tundra tire equipped Piper PA-12 airplane, N7944H, sustained substantial damage when it nosed over during taxi for takeoff at an off airport gravel bar on the Susitna River, about 22 miles west of Big Lake, Alaska, at 61 degrees 28 minutes north latitude, 150 degrees 30 minutes west longtitude. The solo private pilot was not injured. The personal flight was conducted under 14 CFR Part 91. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The pilot told the NTSB investigator-in-charge, during a telephone interview on May 15, and wrote in his NTSB Pilot/Operator report, that he was taxiing for takeoff on a gravel bar. He added that he was "taxiing pretty fast." He indicated that while taxiing, as he was concentrating on the gusty tailwind, the main wheels hit a big bump and ditch which he had not seen, and the airplane nosed over. The pilot stated that he should have watched the area in front of where he was taxiing, and should have walked the takeoff area prior to attempting the takeoff. The airplane sustained damage to the top of the vertical stabilizer, and right wing strut.