SHERIDAN, WY, USA
N316T
Piper PA-18-105
While in cruise, on a local area personal flight, the engine lost power. The pilot attempted to regain power by placing the mixture to rich, applying carburetor heat, and switching fuel tanks. These procedures were ineffective, and the pilot conducted a forced landing beside a road. As the aircraft slowed during landing roll, the main landing gear dug into snow, and the aircraft nosed over. An examination of the aircraft revealed no evidence that would have prevented the engine from operating. The temperature and dew point were 39 and 34 degrees, respectively. According to icing probability charts, conditions were conducive to carburetor ice.
On February 6, 1998, at 1630 mountain standard time, a Piper PA-18-105, N316T, nosed over during landing roll after conducting an emergency landing due to a complete loss of engine power. The private pilot and sole occupant was not injured and the aircraft sustained substantial damage. Visual meteorological conditions prevailed for this local area personal flight operating under Title 14 CFR Part 91 and no flight plan was filed. The flight originated from Sheridan, Wyoming, at 1615. According to the pilot, he was in cruise flight at 6,100 feet above mean sea level (msl) which was approximately 2,000 feet above ground level (agl) when the engine lost all power and the propeller stopped. He said he conducted an emergency landing beside a road approximately 10 miles south of Sheridan. As the aircraft slowed during landing roll, the main landing gear dug into the snow and the aircraft nosed over causing damage to the propeller, cowling, wind screen, the top of both wings, both wing struts, and the rudder. In an interview with the IIC (Investigator in Charge), the pilot stated that following the complete loss of power, he placed the mixture in the full rich position and applied carburetor heat. He also said he changed fuel tanks by switching the fuel feed from the full left tank to the 1/3 full right tank. None of these procedures had any affect on the power loss. An examination of the aircraft by a FAA Airworthiness Inspector, provided no evidence which would have prevented the engine from operating or the propeller from wind milling. The outside air temperature at Sheridan (3,900 feet msl) at the time of the accident was 39 degrees and the dew point was 34 degrees. Assuming a standard temperature lapse rate of 3 degrees per thousand foot change in altitude, and the pilot reported cruise altitude of 6,100 feet msl, the outside air temperature would have been 33 degrees and the dew point 29 degrees. According to FAA Advisory Circular 82-44, dated June 1982, these temperatures are in the range where carburetor ice can form at both climb and cruise power. A test run of the engine was not feasible.
the pilot's improper use of carburetor heat, which resulted in loss of engine power due to carburetor ice. Factors relating to the accident were: the carburetor icing (weather) condition, and the lack of a suitable area for an emergency landing.
Source: NTSB Aviation Accident Database
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