Overview
The accident occurred during departure from an uncontrolled public airport. The runway selected by the pilot measured 4,600 feet in length with a 1.8 percent upward gradient. At the time of departure, the density altitude was 4,937 feet mean sea level, and a slight quartering tailwind was present. The reciprocal runway would have departed toward decreasing elevations.
Departure and Witness Observations
The pilot held the airplane in position, increased engine power, and initiated the takeoff roll. Witnesses observed the aircraft using most of the available runway length before rotating into a higher-than-normal pitch attitude during the initial climb. The airplane then turned left, following the path of a canyon, and continued into rising terrain. Two witnesses reported that just before the crash, the airplane was at a low altitude, nose high, and wallowing. It subsequently descended into a drainage area located approximately 0.69 miles from the departure runway.
Post-Crash Examination
The accident site was situated in a canyon, with wreckage and ground scars confined to an area roughly the diameter of the wingspan. A post-crash fire consumed major portions of the airframe and most engine accessories. Examination confirmed that all major components of the airframe and powerplants were present at the site. Inspection of the engines revealed worn camshaft lobes and tappets, conditions that would negatively affect the engines' ability to produce full rated power. Additionally, one engine exhibited severe rust on its entire crankshaft.
Probable Cause
The pilot's failure to attain and maintain a sufficient airspeed, which led to an inadvertent stall mush. The pilot's selection of the wrong runway for departure, considering the uphill gradient, the wind direction, and a takeoff path into rising terrain are also causal. The high density altitude and the degraded internal condition of the engines were factors.