ERA21LA125 · Taylorcraft BC-65

The student pilot was making a solo flight in the airplane. The airplane was in cruise flight at 2,000 ft mean sea level (msl) when the engine began to gradually lose power. The pilot applied full carburetor heat but turned it back off as it resulted in a loss of engine rpm. The engine eventually stopped producing power, and the pilot made a forced landing to a road located in a subdivision that was under construction. The airplane sustained substantial damage when it collided with construction equipment during the landing roll. Examination of the engine and airplane revealed no mechanical issues that would have precluded normal operation. Weather modeling for the accident time and location indicated that at 1,752 ft msl the temperature was about 44°F; the dew point was about 33°F; and the relative humidity was about 66%. At 2,351 ft msl, the temperature was about 41°F; the dew point was about 33°F; and the relative humidity was about 72%. Review of the icing probability chart contained within Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin (SAIB) CE-09-35 revealed the atmospheric conditions at those altitudes at the time of the accident were conducive to “serious icing at cruise power.” Therefore, it is likely that the loss of engine power was due to the accumulation of carburetor ice. When the pilot applied carburetor heat, the drop in engine rpm that occurred was likely due to the ice beginning to melt, which introduced water into the fuel/air mixture. If the pilot had left the carburetor heat full on, it is likely engine power would have been restored.

Verbatim NTSB analysis and probable cause from the NTSB dataset