On June 25, 2000, about 2000 Alaska daylight time, a tundra tire equipped Piper PA-18 airplane, N7437, sustained substantial damage when it contacted brush during landing on a remote airstrip on the Kustatan River, about 28 miles west-northwest of Nikiski, Alaska, at 60 degrees, 58 minutes north latitude, 152 degrees, 00 minutes west longitude. The private pilot and the one passenger on board received no injuries. The personal flight was conducted under 14 CFR Part 91, and departed the Arness Lake airstrip at Kenai, Alaska, at 1915. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The pilot told the NTSB investigator-in-charge (IIC) during a telephone interview on June 26, and wrote in her NTSB Pilot/Operator report, that during the landing flare on the 900 feet long by 45 feet wide gravel airstrip, a bear ran onto the landing area. The pilot said she maneuvered to avoid the bear and applied the brakes. The right wing contacted brush, and the airplane was pulled off the right side of the airstrip. The airplane sustained substantial damage to the both wingtips, and the tail assembly.