Incident Summary
The aircraft was destroyed during a high-velocity impact with terrain. While cruising at 5,500 feet, the pilot reported a "severe vibration" and stated that he was diverting to a nearby airport.
Flight Path
Aircraft radar track data was collected from radar facilities along the route of flight. The plotted data showed that the airplane departed the Minneapolis metropolitan area to the northeast and continued on a northerly heading toward Duluth, Minnesota. The aircraft's ground speed averaged about 100 knots while on the northerly heading. A plot of the radar data indicated that the airplane made a course reversal to a southerly heading just prior to the accident. The last radar return was approximately 0.8 nautical miles northeast of the accident site. During the final 38 seconds of aircraft radar track data, the airplane's calculated ground speed increased from 130 knots to 218 knots while established on the southerly heading. The aircraft's maximum structural cruising speed was 121 knots and the never exceed speed was 151 knots. The current winds aloft forecast indicated that the winds at 3,000 and 6,000 feet were out of the north, between 4 and 12 knots.
Impact and Wreckage
The wreckage was located in an open area about 950 feet long and 400 feet wide. The initial impact crater was 11 feet long, 7 feet wide, and 3 feet deep. A 38-foot-long ground depression ran perpendicular to the crater. The ground depression was similar in length to the accident airplane's wingspan. All primary airframe structural components, flight control surfaces, engine components, and propeller blades were located within the debris field. Fragmented wreckage was found up to 190 feet from the initial impact crater.
Aircraft Examination
No anomalies were noted with the airframe, flight control systems, engine, or propeller that could be associated with a pre-impact malfunction.