Primary finding
Probable cause
A partial loss of engine power due to carburetor ice.
Investigator assessment
Analysis narrative
About 30 minutes after departing on a cross-country flight, the pilot heard the engine “misfire,” but observed that all engine instruments and temperatures appeared normal. The engine misfired again, and he decided to return to his departure airport. A few minutes later, the engine lost partial power. Unable to maintain altitude, the pilot elected to divert to a nearby airport. During the landing roll, the airplane exited the runway surface, nosed over, and came to rest inverted. The airplane sustained substantial damage to the vertical stabilizer and rudder. Postaccident examination of the airframe and engine revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Based on the reported weather conditions at the time of the partial power loss, the airplane was operating in conditions conducive to the formation of serious icing at glide power. The pilot reported that he applied carburetor heat and felt that application exacerbated the problem, so he turned off the carburetor heat and continued with the forced landing. It is likely the engine sustained a partial loss of engine power due to the formation of carburetor ice and that the pilot likely turned off the carburetor heat before the ice melted.
Source record
Factual narrative
On August 3, 2024, about 1000 central daylight time, an experimental, amateur-built Tailwind W10 airplane, N129WT, was substantially damaged when it was involved in an accident near West Livingston, Texas. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, he departed his local airport for a cross-country flight. About 30 minutes into the flight, he heard the engine “misfire,” but all engine instruments and temperatures appeared normal. The engine misfired again, and he decided to return to his departure airport. A few minutes later, the pilot experienced a significant loss of engine power, and elected to divert to a nearby airport. The pilot stated he did not have a lot of time to troubleshoot and executed a forced landing to the airport. During the landing roll, the airplane exited the runway surface, nosed over, and came to rest inverted. At some point while experiencing the engine issues, the pilot applied carburetor heat, which he felt exacerbated the problem, so he turned off the carburetor heat and continued the forced landing. Postaccident examination of the airplane revealed substantial damage to the vertical stabilizer and rudder. Engine continuity was confirmed, and a compression check of the cylinders, and examination of the spark plugs and the ignition system all showed no anomalies. Fuel was observed in the fuel lines to the carburetor, and fuel flowed freely into the carburetor. Engine control continuity was confirmed. The examination revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. A review of the Carburetor Icing Probability Chart located in the Federal Aviation Administration’s Special Airworthiness Information Bulletin CE-09-35, Carburetor Icing Prevention, dated June 30, 2009, indicated that the atmospheric conditions in which the airplane was operating were conducive to the formation of serious icing at glide power settings.