On September 4, 2002, about 1800 Alaska daylight time, a tundra tire-equipped Piper PA-18 airplane, N2410P, sustained substantial damage when the right wing struck a tree stump while taxiing for takeoff from a remote, off-airport site, about 13 miles east-southeast of Nikolai, Alaska. The airplane was being operated as a Title 14, CFR Part 91 visual flight rules (VFR) personal flight when the accident occurred. The airplane was operated by the pilot. The commercial certificated pilot, and the sole passenger, were not injured. Visual meteorological conditions prevailed. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on September 5, Federal Aviation Administration (FAA) personnel reported the pilot had contacted an over-flying airplane via radio to report the airplane disabled. On September 6, the pilot telephoned the NTSB IIC and reported that he was taxiing in preparation for takeoff along the edge of the south fork of the Kuskokwim River. The gravel area he was utilizing had several tree stumps along the river bank. The pilot said that while taxiing, the right main landing gear tire entered a small, soft, depression. The right wing dipped downward and struck a tree stump. On September 10, the pilot reported that an examination of the right wing revealed damage to the leading edge and rear spar.