Flight Progress
The pilot was descending from 6,000 feet MSL when IFR flight plan was canceled and clearance was issued for a VFR approach to Boeing Field in Seattle. Radio and radar contact with the aircraft was subsequently lost at 2,600 feet MSL. The wreckage was found 14.8 miles from the destination airport.
Separation Event
Examination of the wreckage revealed that both wings and the stabilator had separated from the airframe while the aircraft was still in flight.
Performance Study
A performance study indicated that the in-flight breakup occurred at 5,100 feet MSL during a descent at an indicated airspeed of 205 knots. The never-exceed speed (Vne) for this airplane is 195 knots indicated airspeed.
Cargo Considerations
The route description for the flight specified that after landing at Boeing Field, Burlington Northern freight would need to be transferred via vehicle to SeaTac Airport, with a delivery deadline of 2230. It was noted that the aircraft's aft center of gravity was exceeded by 1.68 inches.