On August 8, 1997, about 1730 Alaska daylight time, a tundra tire equipped Piper PA-18 airplane, N339T, sustained substantial damage when it contacted brush and ground looped during landing at an 1,100 feet long by 50 feet wide grass private airstrip, 28 miles southeast of Circle, Alaska. The solo private pilot was uninjured. The airplane was operated by Ingo, Inc., of Fairbanks, Alaska. The flight was conducted under 14 CFR Part 91 as a personal flight, visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The pilot stated that upon touchdown, the right wing contacted brush along the side of the airstrip, and the airplane ground looped. The pilot had landed at this same airstrip on previous occasions. He said that brush had grown into the approach end of the strip. During a telephone interview with the FAA, and in his NTSB Pilot-Operator Report, the pilot indicated he was tired. He also stated that he wanted to use the entire landing length available, and did not see the brush which had grown into the airstrip.