What happened
The incident occurred while the aircraft was en route to its destination. Air traffic control previously advised the pilot of visual flight rules traffic located at his one o'clock position, approximately 12 miles away on a northwest heading. The pilot acknowledged the information but stated he had no visual contact and noted that the weather conditions were slightly hazy. Shortly thereafter, air traffic control informed the pilot that the other aircraft had cleared the area, to which the pilot acknowledged.
This transmission marked the last known communication from the cockpit. At approximately the same time, a pilot flying a Piper PA-28 on a 150-degree heading observed another aircraft at his one o'clock position on an easterly heading, roughly one mile ahead. The observer reported that the aircraft was in a shallow nose-down pitch attitude and appeared to be traveling at a high speed. As the aircraft moved to the observer's eleven o'clock position, it suddenly came apart in mid-air.
The breakup occurred at an altitude of approximately 5,000 to 5,500 feet. The wreckage was found fragmented and scattered over an area spanning 3,000 feet in an east-west direction. Significant structural separations were noted, with the stabilators having separated from the empennage and the wings detaching from the fuselage.
The investigation
Examination of the debris field revealed that the wing center spar was bent and had failed due to overload. A weather study indicated the presence of light to moderate turbulence at altitudes between 7,000 and 8,000 feet mean sea level during the time of the incident. Inspection of the cabin showed that seat belts and shoulder harnesses were unfastened but undamaged.
Findings
The structural failure was linked to aerodynamic loads exceeding design limits. N999YP was identified as the aircraft involved in the breakup. The presence of light to moderate turbulence at nearby altitudes suggests that atmospheric conditions may have contributed to the excessive stress on the airframe, leading to the catastrophic failure of the wing center spar and subsequent disintegration.