On February 16, 2002, about 1030 Pacific standard time, a Piper PA-18-150, N9299D, nosed over during landing at Beatty, Nevada. The private pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The pilot, the sole occupant, was not injured; the airplane sustained substantial damage. The personal local flight departed Beatty about 1000. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot said he was practicing touch-and-go landings. On the accident landing, he landed on centerline and the airplane started to drift to the right. He applied left rudder but felt that was ineffective. He touched the left heel brake and the airplane immediately nosed over. The pilot said the airplane had a 30.5-gallon fuel tank in each wing. The right tank was 1/2 full and the left tank was 3/4 full. The pilot thought the right brake must have grabbed when he touched the left brake. He thought the fuel must have sloshed forward and caused the nose to drop. The pilot plans to replace the heel brakes with toe brake pedals, and replace the fuel tanks with 12-gallon tanks.