On August 5, 1998, at 1200 central daylight time (cdt), a Cessna 182M, N514HP, owned and operated by a private instrument rated pilot, was substantially damaged following a loss of engine power and subsequent forced landing short of Trenton Municipal Airport, Trenton, Nebraska. The pilot reported serious injuries. The passenger reported minor injuries. The personal 14 CFR Part 91 flight was operating in instrument meteorological conditions. An IFR flight plan had been filed. The flight originated from Rock Springs, Wyoming, at 0810 Mountain Daylight time (mdt), with an intended destination of Cambridge, Nebraska. The pilot reported that he checked the fuel quantity during his preflight and the airplane had approximately 80 gallons of fuel onboard. The pilot reported that while en route, upon reaching a cruise altitude of 13,000 feet, he leaned the fuel mixture to "75 degrees below highest EGT." He reported that about 3 hours into the flight the lost total power, regained power, then lost total power again. He reported the power loss to the Denver Air Route Traffic Control Center and was vectored to the Trenton Airport, 17 miles away. The pilot reported that upon reaching the airport he was too high so he circled downwind to the runway. He reported that during this time, "I lost more altitude than I expected and felt dangerously low, maybe not able to reach the runway on turning inbound." He reported that he had the airplane slightly above stall speed and the airplane "...stalled too high and dropped on the runway." A witness to the accident reported seeing the airplane stall and contact the terrain. He reported the airplane bounced and touched down again with the nose and right wing contacting the terrain. According to the Hitchcock County Sheriff's Department the airplane "... came into the approach of the runway lower that the ground level of the runway, and the front landing gear of the aircraft struck the heavy grass and buckled. The aircraft nosed down into the grass on the approach of the runway and skidded to a stop causing the aircraft to tip upward and forward." Post accident inspection of the airplane by and Inspector from the Federal Aviation Administration (FAA), Lincoln, Nebraska, Flight Standards District Office revealed only residual fuel remained in the fuel tanks. The master switch was turned on and the right fuel gage indicated 1/8 tank of fuel, the left fuel gage indicated empty. The fuel system was inspected and no signs of fuel leakage were noted. Further inspection by a mechanic from Beegles Aircraft Services, Greeley, Colorado revealed, "The snaps that hold the bladders to the top of the compartment were all found to be unsnapped. There are 8 snaps on each bladder and one of the snaps was missing from the RH fuel tank." According to the FAA Inspector, both fuel bladders were pushed forward in the tanks. The pilot reported he departed Rock Springs, Wyoming with 80 gallons of fuel on board which he verified during the aircraft preflight. Fuel records and a Unicom log show the last flight previous of the accident flight was on July 30, 1998. The airplane was refueled with 27.6 gallons of fuel after this flight.