Summary
During the final approach, the pilot reported that the engine was losing power. He elected to perform a go-around, during which the airplane collided with trees off the departure end of the runway.
Investigation Details
An FAA inspector examined the wreckage. The inspection did not disclose evidence of any mechanical malfunction. The fuel tank was intact and observed to be about three-quarters full. The FAA inspector's report stated, "the engine appears to have been running at time of impact... There was no apparent reason for the engine to quit."
Additionally, the facility where the airplane had last been refueled was tested for fuel contamination, with negative results.