What happened
The aircraft departed Portland International Airport to perform a maintenance check flight. After climbing to 1,900 feet MSL, the pilot proceeded to overfly their residence, an action noted by the pilot's wife as being relatively common.
Radar data indicated that the aircraft was flying in a left 360-degree circle at 1,900 feet MSL, which was approximately 1,000 feet above the ground, before radar contact was lost. Witnesses on the ground confirmed the aircraft was performing a circular orbit. During the early stages of the second orbit, observers saw the aircraft execute a steep left turn. During this maneuver, the nose of the aircraft dropped and the plane began a descent.
The aircraft struck a tree at a height of approximately 110 feet above the ground impact site, which severed the outboard section of the left wing. Following this impact, the aircraft descended to the ground while rolling left about its longitudinal axis.
The investigation
An examination of the engines following the crash revealed prop slash marks that indicated the left engine was at approximately 2,200 RPM and the right engine was at approximately 2,900 RPM at the time of ground impact. A post-crash examination of the aircraft found no evidence of any control malfunction.