Weather Briefing and Flight
During a weather briefing, the pilot was advised that the forecast across South Dakota for the eastern third of the state indicated scattered to broken clouds at 2,500 feet AGL with an overcast layer at 5,000 feet, occasional visibilities of three to five miles in light snow. The flight subsequently experienced an in-flight breakup.
Structural Damage
The wings were fractured at the roots with evidence of positive overload. The empennage separated from the tail cone with evidence of torsional overload.
Environmental Conditions
According to local residents, low visibility existed in the vicinity of the accident due to fog and blowing snow.
Weight and Balance
Airplane weight and balance calculations indicated that the center of gravity was beyond the aft center of gravity limit.
Toxicology Findings
Toxicological tests detected dextromethorphan in the liver fluid (0.009 ug/ml) and kidney fluid (0.007 ug/ml). Pseudoephedrine was also detected in liver fluid. Additionally, a substance was detected but not quantified, which according to the manager of the FAA Toxicology and Accident Research Laboratory "appears to be an ergotamine type compound."
Medical History
Examination of the pilot's personal medical records revealed medical treatment for an "asthma flare" 17 days prior to the accident.