Cessna 320D N32EG accident near Green River, Wyoming

Probable cause

The pilot's failure to maintain airplane control while maneuvering in marginal weather conditions, which resulted in an exceedence of the design stress limits of the airplane and a subsequent in-flight structural failure.

NTSB analysis

The non-instrument rated pilot departed in the high-performance multiengine airplane on a cross-country flight over mountainous terrain. Mixed rain and snow showers were reported in the area, and lightning flash data and surface observations indicate vigorous snow shower activity around the time and location of the accident. Recorded radar returns believed to be associated with the accident airplane showed a radar track on a westerly heading at cruise altitudes between 10,000 and 12,000 feet mean sea level. The radar track then depicted a descending 720-degree turn over the course of several miles. Following the turn, the radar track showed multiple heading and altitude changes over the course of about 2 minutes. The last observed radar return was about 0.4 mile from the accident location. The wreckage debris was scattered over an area about 0.4 mile in length. Pieces of the cockpit and a section of the right elevator were located at the southeast perimeter of the debris field; the fuselage and both engines located at the opposite, northwest, end of the debris field. Sections of the wings, flight control surfaces and horizontal stabilizer were also scattered between the beginning of the debris field and the main wreckage.

Examination of the wing and horizontal stabilizer spars fracture surfaces showed features consistent with overstress separation in-flight and no evidence of fatigue was noted.

Given the radar track, the length of the wreckage debris field, and the marginal weather conditions, it is likely that the break-up sequence was inadvertently induced as the pilot attempted to maneuver the airplane out of marginal weather conditions, which ultimately led to an exceedence of the design stress limits of the airplane.

Text from the NTSB. Open the NTSB docket for WPR12FA164 for the full record.