CEN24LA119 · Zenith STOL CH750

The pilot reported that he had recently changed the carburetor on the experimental, amateur-built airplane’s engine, and the accident flight was his third flight with the new carburetor. Although the previous flights had been uneventful, he thought that the fuel/air mixture was too rich. He stated that he intended to remain in the airport traffic pattern during the accident flight; however, he had no memory of the events of the flight. A witness reported seeing the airplane as it was departing the airport. The witness reported that the airplane was flying about 60 ft above ground level (agl) and climbed to about 100 ft agl followed by a shallow, descending left turn. The witness did not hear any engine noise and thought that the propeller was not spinning. The witness noted that the airplane was traveling very slow and then dropped straight down. The airplane impacted terrain and came to rest in a field less than 1 mile from the airport. Examination of the airplane, engine, and systems revealed no evidence of any preimpact anomalies that would have precluded normal operation. The propeller blades did not exhibit signs of rotation at the time of impact. The witness, who responded to the accident site, reported that there was an odor of fuel at the site. Based on the available information, it is likely that the engine lost power shortly after takeoff. The witness’ account of the airplane traveling “very slow” and descending “straight down” is consistent with a loss of airplane control.

Verbatim NTSB analysis and probable cause from the NTSB dataset