Amateur-built ACRODUSTER accident near Belton, South Carolina, April 24, 2016

The NTSB's narrative final · quoted from the NTSB record

The pilot was returning to the airport from a local personal flight. The airplane completed two low approaches and then made a left turn to reenter the traffic pattern. Two witnesses reported that, when the airplane was on the downwind leg of the traffic pattern, the engine sound changed; one reported that the engine sputtered and "cut out." The airplane then banked left and pitched nose down before impacting the ground, consistent with an aerodynamic stall. The propeller governor was examined, and no pre-impact anomalies were noted. The examination noted scrape marks on the propeller governor. According to the manufacturer, the scrape marks were made when the gears were turning opposite the direction of normal rotation, indicating that the propeller was not rotating to propel the airplane forward when the marks were made. An examination of the airframe and engine revealed no evidence of pre-impact mechanical malfunctions or failures; however, extensive thermal damage precluded a detailed examination. Additionally, the airplane's fuel state prior to the accident could not be accurately determined. Toxicological testing identified 0.024 ug/ml of diphenhydramine in heart blood and detected diphenhydramine in urine. The postmortem blood diphenhydramine level was below the therapeutic range, which suggests that the pilot's level was likely below therapeutic and impairing levels at the time of the crash. Therefore, it is unlikely that the pilot's use of diphenhydramine at some time before the accident flight contributed to the accident.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.