Primary finding
Probable cause
A partial loss of engine power due to loose bolts holding the carburetor throttle body to the fuel bowl.
Investigator assessment
Analysis narrative
The pilot reported that shortly after takeoff the engine began running rough and the engine lost partial power. The pilot made a forced landing back to the departure airport. During the landing, the airplane touched down hard and departed the side of the runway, which resulted in substantial damage to the left wing. Postaccident examination of the carburetor revealed fuel stains around the outside of the fuel bowl and in the throat of the fuel bowl. Five of the six bolts holding the throttle body to the fuel bowl were found only finger-tight. The partial loss of engine power was most likely the result of air being drawn into the fuel bowl due to the loose bolts. The last annual inspection was completed on the engine in January of 2023. Investigators did not determine the last time maintenance was specifically performed on the carburetor.
Source record
Factual narrative
On June 17, 2023, about 0845 central daylight time, a Cessna 172B, N7509X, was substantially damaged during a forced landing at San Angelo Regional Airport (SJT), San Angelo, Texas. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that after departure from runway 36 the engine began running rough and a partial loss of power occurred. The pilot flew a forced landing to runway 9, during which the engine continued to run rough. The airplane touched down hard and departed the side of the runway, which resulted in substantial damage to the left wing. Postaccident examination of the carburetor revealed fuel stains around the outside of the fuel bowl. Five of the six bolts holding the throttle body to the bowl were found finger-tight. The float setting was set overly rich and wear was observed on the tip of the float needle. The last annual inspection was completed on the engine on January 1, 2023. Investigators did not determine the last time maintenance was specifically performed on the carburetor. The airplane had flown about 13 hours since the last annual inspection was completed on the airplane.