NTSB Identification: LAX07FA103
14 CFR Part 91: General Aviation
Accident occurred Wednesday, March 07, 2007 in Tooele, UT
Probable Cause Approval Date: 01/29/2009
Aircraft: PIPER PA-28-235, registration: N9381W
Injuries: 3 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The airplane broke apart in flight while the pilot was maneuvering at cruise altitude. A witness in another airplane, who was 4 to 5 miles in trail of the accident flight at the same altitude, clearly saw the strobe lights of the accident airplane in front of him. The witness climbed to 9,500 feet and encountered what he described as cumulonimbus clouds and light icing. He stated that the temperature was 32-34 degrees Fahrenheit. He descended to 7,500 feet where he encountered severe turbulence, which caused him to hit his head violently against the cabin ceiling. He observed that he was below the accident airplane, and estimated that it was at 8,500 feet. He then lost sight of it. Radar data indicated that the accident flight turned left, and then began a descending right turn. The airplane broke apart during the turn. The fracture surfaces indicated a positive overload condition on all separated wing and tail components, with significant permanent set deformation of major structural elements in the wings and tail observed. A metabolite of diazepam (a prescription anti-anxiety medication commonly known by the trade name Valium), was found in the pilot's kidney and liver on toxicology testing. The pilot had a prior history of anxiety and depression that was treated with medication, though he had reportedly not received any recent medical treatment or medication. No blood or urine was available for analysis, so it is not possible to estimate when in the previous days or weeks that diazepam might have most recently been used or to determine the relevance, if any, of the medication or the condition for which it was used.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot exceeded the design stress limits of the airplane, which resulted in the in-flight separation of the wings and horizontal stabilizers. Contributing to the accident were the night lighting conditions, clouds, turbulence and icing conditions.

Full narrative available

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