Piper PA 14 accident near Susanville, California, August 15, 2020

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

The accident airplane’s takeoff run from a dirt runway was not observed. However, while taxiing his airplane toward the airport’s only asphalt runway, a friend of the accident pilot and pilot-rated passenger observed the accident airplane in a steep left turn about 350 ft above the runway. The airplane then transitioned into a nose-down dive, consistent with a loss of control following an accelerated stall, which resulted in impact with terrain. Examination of the wreckage revealed no preimpact mechanical anomalies with the engine or airframe that could have precluded normal operation. An experimental propeller that was designed for a more powerful engine was attached to the engine at the time of the accident. The propeller’s blade angle was excessive for the engine-propeller configuration, which would have slowed the propeller. This, in turn, would have led to an overall decrease in performance, further degrading the airplane’s ability to climb as the density altitude was nearly double the field elevation of the departure airport when the accident occurred. Additionally, the airplane may have been over its gross weight; however, this could not be determined as the fuel quantities at the time of departure were unknown. The airplane had vortex generators installed, which may have slightly reduced the airplane’s stall speed, but this performance improvement was not guaranteed as stated by the manufacturer. The investigation was unable to determine whether the pilot performed any preflight performance computations, which would have showed that the airplane required 3,750 ft of runway surface to clear a 50 ft obstacle given the temperature and density altitude. Although there was no need to clear a 50 ft obstacle that day, and this performance information was for a lower performance engine than the one he had installed, a conscientious pilot would have exercised caution during the takeoff attempt after reviewing this performance data. However, the witness observation of the airplane altitude is consistent with the pilot performing a high rate of climb departure after takeoff. The pilot’s toxicology testing demonstrated previous use of cocaine, but no active cocaine in his system at the time of the event. The investigation was unable to determine if he had any impairment from cocaine withdrawal at or near the time of the accident and whether his cocaine use contributed to the accident circumstances due to a lack of available evidence.

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.