Westwind Aviation Flight 58

According to the pilot, he was departing about 50 pounds under gross weight. The paved 8,999-foot runway is located at 6,606 feet msl. The winds were down the runway about 20 to 25 knots, with the temperature about 50 degrees, and the density altitude about 8,100 feet msl. About 3/4 down the runway's length the pilot aborted the takeoff. He taxied back to the terminal and off loaded a passenger, who he estimated to be about 300 pounds. He now estimated the airplane to be about 350 pounds below the gross weight limit. The pilot was again cleared for takeoff. He started his takeoff with the mixture full rich, and then gradually leaned the mixture to about 20 gallons per hour. He said the acceleration felt slow, but normal for a loaded airplane. After becoming airborne, about 100 feet agl, the airplane's climb performance seemed to be getting worse, and it was too late to abort. The control tower advised a 15-degree right turn towards lower terrain, which the pilot performed clearing tree tops about 50 feet. He reported that all preflight and in-flight checks were normal. He performed additional in-flight checks of the engine systems, including simultaneous use of the fuel boost pumps, with no increase in performance. About 10 minutes into the flight, the airplane was still 50 to 100 feet above treetops and approaching high-tension power lines without enough altitude to clear them. The pilot started to look for a landing site. Subsequently the airplane collided with trees about 14 miles from the departure point. Examination of the magnetos by the manufacturer revealed numerous discrepancies affecting the optimum performance of the engine.

Verbatim NTSB analysis and probable cause from the NTSB dataset