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| NTSB Identification: CHI97LA037. The docket is stored in the (offline) NTSB Imaging System. |
| Accident occurred Wednesday, November 27, 1996 at BOWBELLS, ND |
| Aircraft: CESSNA 150, registration: CGOCS |
| Injuries: 2 Uninjured |
| Event: 20001208X07014 Status: Final Report Approved On Friday, May 23, 1997 |
| NTSB Preliminary Narrative (6120.19A) |
| On November 27, 1996, at 1250 central standard time, a Canadian registered Cessna 150, C-GOCS, piloted by a private pilot, was substantially |
| damaged during an off-airport landing in 18-inch deep snow following a partial loss of engine power. The 14 CFR Part 91 instructional flight was |
| operating on a VFR flight plan. The pilot and passenger reported no injuries. Visual meteorological conditions prevailed at the time of the |
| accident. The flight departed Minot, North Dakota, exact time unknown. |
| The pilot reported the airplane was at 6,500 feet above mean sea level when he "...noticed a sudden drop in the [engine] RPM and a stuttering |
| noise." He said he applied carburetor heat and placed the mixture control to full rich. He said, "We continued to have stuttering along with drops |
| in the RPM." |
| During an interview, the pilot said he was informed the airport had no winter maintenance as he made his initial approach to the Bowbells |
| Municipal Airport, Bowbells, North Dakota. The pilot said he headed toward what he believed was a flat landing surface with a little sanow on it. |
| As he approached the chosen field, he said he noticed it was a hill and landed in a field next to it. |
| The Cessna 150 Pilot Operating Handbook section on the use of carburetor heat states, "Carburetor ice.... can be removed by application of full |
| carburetor heat. Upon regaining the original RPM (with heat off), use the minimum amount of heat (by trial and error) to prevent ice from forming. |
| Since the heated air causes a richer mixture, readjust the mixture setting when carburetor heat is to be used continuously in cruise flight." |
| The on-scene investigation was conducted by a Federal Aviation Administration Principal Maintenance Inspector (PMI). According to the PMI, |
| there were no mechanical or fuel anomalies that would have caused the engine to stop running. He said the nose gear had been pushed aft into |
| the bottom of the firewall. According to the PMI, fuel samples taken from the wing tanks did not have ice crystals in them. The PMI said he |
| "...found ice crystals in the carburetor's venturi/injector section and float section... ." |
| NTSB Final Narrative (6120.4) |
| While in cruise flight, the pilot said his RPM suddenly dropped and the engine began to make a '...stuttering...' noise. He said he applied |
| carburetor heat and positioned the mixture to full rich. The engine continued to make the stuttering noise and have '...drops in the RPM.' As he |
| approached an alternate airport he said he was informed the airport had no winter maintenance. He said he selectd a field that appeared flat |
| with a little snow on it for a landing. As he approached the field he said it was a hill and landed next to it. An on-scene investigation revealed no |
| mechanical or fuel anomalies that would cause the engine to stop running. The nose gear crushed the bottom of the firewall when it was bent |
| aft during the landing. Ice crystals were found in the carburetor venturi and float bowl. |
| NTSB Probable Cause Narrative |
| the pilot's failure to lean the mixture control after applying carburetor heat as the pilot's operating handbook states should be done. The |
| carburetor icing conditions and the terrain were factors. |
| Occurrences and Sequence of Events |
| Occurrence: 1, LOSS OF ENGINE POWER(PARTIAL) - NONMECHANICAL |
| Phase of Operation: CRUISE |
| Sequence of Events for Occurrence Number: 1 |
| 1 ( Factor ) WEATHER CONDITION / CARBURETOR ICING CONDITIONS / (0) |
| 2 ( Cause ) MIXTURE / IMPROPER USE OF / PILOT IN COMMAND |
| 3 ( Cause ) FUEL SYSTEM, CARBURETOR / ICE / (0) |
| Occurrence: 2, FORCED LANDING |
| Phase of Operation: EMERGENCY LANDING |
| Occurrence: 3, IN FLIGHT COLLISION WITH TERRAIN/WATER |
| Phase of Operation: LANDING - ROLL |
| Sequence of Events for Occurrence Number: 3 |
| 1 ( Factor ) TERRAIN CONDITIONS / SNOW COVERED / (0) |
| 2 ( Factor ) TERRAIN CONDITIONS / ROUGH/UNEVEN / (0) |
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