What happened
During the approach phase of flight, the aircraft struck the ground, resulting in the destruction of the plane and fatalities for all occupants. Prior to the impact, the aircraft was operating under visual meteorological conditions beneath an overcast cloud layer. Radar tracking indicated that the aircraft was following a left-hand traffic pattern for runway 34. During this maneuver, the aircraft's speed decreased to approximately 82 knots calibrated airspeed. The final radar contact occurred roughly 0.1 nautical miles from the crash site and 0.8 nautical miles from the approach end of the runway.
Technical data from the aircraft's manual indicated that stall speeds for various configurations, including those with gear and flaps extended up to 15 degrees, ranged between 81 and 94 knots. The recommended approach speed for the aircraft was 103 knots. While the position of the flaps could not be verified due to a mechanical failure in the flap drive motor chain, the aircraft was flying at a speed near the lower limit of its stall range.
Findings
An investigation of the engines and propellers showed no mechanical anomalies present before the impact. Both propellers were operating within their normal range and were not in a feathered position. Analysis of the engine quill shafts indicated damage resulting from torque production. Furthermore, audio spectrum analysis of radio transmissions confirmed that both engines were functioning during the final two communications received from the aircraft. The investigation determined that the aircraft was flying at a speed dangerously close to its stall threshold during the turn.