On July 23, 1997, at 2200 Alaska daylight time, a Cessna 180 airplane, N2707X, sustained substantial damage while taxiing on a gravel bar in the Colville River, about 68 miles southwest of Umiat, Alaska. The commercial certificated pilot and the one passenger aboard were uninjured. The flight was conducted under 14 CFR Part 91 as a personal flight. Visual meteorological conditions prevailed at the time of the accident. The flight departed Umiat, Alaska, at 2100 on July 23, 1997, and the pilot stated he had filed a flight plan with an acquaintance in Umiat. The pilot said he was not due to return to Umiat for four days. During a telephone conversation with the NTSB investigator-in-charge, the pilot reported he had completed the landing roll, and was taxiing the airplane to a parking area when the right main landing gear collapsed. He said he was unable to establish radio communications with any aircraft, and activated his emergency locator transmitter (ELT). This signal was received by the Air Force Rescue Coordination Center (RCC) in Fairbanks, Alaska, at 0009 on July 24, 1997. A helicopter was dispatched from Barrow, Alaska, and the pilot and passenger were recovered at 0335 on July 24, 1997. The pilot did not complete an NTSB Pilot/Operator Report as requested.