# NTSB CHI97LA037: Cessna 150, Bowbells, ND, November 27, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 27, 1996, 12:50 local (18:50 UTC) - Place: Bowbells, ND - Coordinates: 48.799354, -102.239639 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=48.7994&lon=-102.2396&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report May 23, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 10496 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI97LA037 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10496/pdf - Page: https://openairdocs.org/ntsb/CHI97LA037 ## Probable cause 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. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - nonmechanical, cruise - weather condition - carburetor icing conditions (contributing factor) - mixture - improper use of, pilot in command (cause) - fuel system,carburetor - ice (cause) - Forced landing, emergency landing - In flight collision with terrain/water, landing - roll - terrain condition - snow covered (contributing factor) - terrain condition - rough/uneven (contributing factor) ## Analysis 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. ## Factual narrative 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... ." ## Aircraft - Registration: CGOCS (not matched to a registry record) - Reported make and model: CESSNA 150 - Category: Airplane - Serial number: 15075899 - Engines: CONTINENTAL O-200 100 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Registered owner: Nimbus Aerobatics, Ltd. - Airworthiness certificate: Standard, Normal; Standard, Utility - Departed: MOT, MINOT, ND - Flight plan: VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 20; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 95 total ## Weather - Conditions: Visual (VMC), Day - Wind: 225° at 7 knots - Visibility: 50 statute miles - Lowest ceiling: none - Temperature: 3 °F From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.