On August 20, 2000, approximately 1320 Pacific daylight time, a Piper PA-18A-150, N6985D, registered to Willamette Valley Soaring Club, Inc., and being flown by a commercial pilot, was substantially damaged during a nose over on landing roll at the North Plains gliderport, North Plains, Oregon. The pilot sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed. The flight, which was reported to be returning from a glider tow operation, was operated under 14CFR91, and originated from the gliderport approximately 1305. The pilot reported that he had been towing in a PA-25-260 aircraft and was asked to switch to the PA-18A-150. He stated that he pre-flighted N6985D and then "...did one warm-up pattern & [a] good wheel landing, then towed 1 tow/glider to 3,000' and returned to land to [the] west, r[igh]t traffic..." and that "...I did a wheel landing app[ro]x[imately] mid field and the a[ir]c[ra]ft flipped over on its back." The pilot reported a total of 2 hours of flight experience in the PA-18A-150 aircraft and had made numerous landings and takeoffs at the gliderport in the previous year. He also stated on NTSB Form 6120.1/2 that he experienced no mechanical malfunction or failure with the aircraft. Witnesses at the airport reported that the aircraft landed long on the westerly runway (approximately 1,200 feet beyond the threshold of the 2,200 foot long grass/turf strip), and was also fast. An FAA inspector who interviewed the pilot after the accident reported that the pilot was making a wheel landing. The tailwheel was still airborne when the aircraft rapidly nosed over. The inspector reported finding no evidence of brake malfunction during his on-site inspection.