CHI95LA311

The pilot said he was flying his airplane about 1,000 feet above a swamp, when the engine lost power. He applied carburetor heat, when he noted an audible indication of the power loss. During a forced in the swamp, the airplane nosed over in water that was two feet deep. The carburetor separated from the engine during the occurrence, but no preaccident/mechanical anomaly was found that would have prevented the production of power. The temperature and dew point were 83 and 66 degrees f, respectively. According to icing probability charts, atmospheric conditions were conducive for carburetor icing.

On September 3, 1995, at 1045 central daylight time (cdt), a Cessna 175, N9425B, piloted by a private pilot, was substantially damaged during a forced landing in a swamp. The pilot reported a total loss of power during cruise flight. Visual meteorological conditions prevailed at the time of the accident. The personal 14 CFR Part 91 flight was not operating on a flight plan. The pilot and one passenger reported no injuries. A second passenger reported minor injuries. The flight departed a restricted landing area near Staples, Minnesota, at 1035 cdt.

According to the pilot's statement on NTSB Form 6120.1/2, "...the engine lost RPM and stopped, I checked all my gauges and found no problem... ." He said the airplane was flying over a swamp at 1,000 feet above the ground. After calling a "mayday" over the radio the pilot said he headed the airplane toward a green field. Soon after doing so he realized it was too far away and ended up landing in the swamp. The airplane nosed over during the landing sequence. It was resting in about two feet of water when the passengers and pilot exited the airplane.

During an interview the pilot said the airplane had its fuel tanks topped off before the flight. He said he did not observe any water in the fuel samples taken during the preflight inspection. The pilot said the airplane's engine "fluttered" one time and then promptly quit. He said he applied full carburetor heat when he heard the flutter sound. He said the engine may have stopped running due to carburetor ice.

The NTSB was represented on-scene by a Federal Aviation Administration (FAA) Principal Maintenance Inspector (PMI). The on-scene examination revealed fuel in N9425B's fuel tanks and engine mechanical continuity. The PMI said the magnetos were examined and sparked when hand rotated. The carburetor had separated from the engine during the collision sequence. Fuel was found in the accelerator pump chamber. No water was observed in the chamber's fuel.

According FAA carburetor icing probability charts, the atmospheric conditions were conducive to carburetor icing. Copies of two charts are appended to this report.