What happened
During a takeoff attempt from a 5,200-foot unpaved runway, an aircraft encountered critical engine issues. The flight departed from a high-elevation strip with a density altitude of approximately 7,250 feet, facing a southern wind of 18 to 20 knots. Witnesses noted the aircraft successfully lifted off and the landing gear began retracting. Shortly after, the pilot reported an in-flight problem. The aircraft was observed performing a right turn at an altitude of roughly 200 to 300 feet before entering a dive. The aircraft eventually struck the ground in a flat attitude approximately half a mile south of runway 17.
Findings
Investigation of the wreckage and onboard video footage revealed that the propellers became out of sync approximately six seconds after takeoff. About 15 seconds later, the right propeller slowed significantly, with the blades becoming visible to observers. Data from the video showed a disparity in fuel flow between the engines, with one engine operating at 90 gph and the other at a minimum setting of roughly 3 psi.
Mechanical examination determined that the right engine-driven fuel pump drive coupling was scored and only partially engaged. While the crew had complied with relevant service bulletins, the auxiliary fuel pump switches were found in the low position. The landing gear was found in the retracted but unlocked position, and the flaps were extended to 15 degrees. Additionally, it was noted that existing emergency procedure training did not adequately account for performance variables involving maximum gross weight and high density altitude. The accident resulted in 10 fatalities.