On June 11, 1993, a Beech 95-C55 (registration N301U) operated by Woodbury County Sheriff's Dept was involved in an aviation accident near Fort Madison, IA. Investigators recorded the probable cause as: The pilot's failure to ensure the cabin door was properly latched, which resulted in a loss of control during the initial climb. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aircraft departed controlled flight and rolled inverted during the initial climb phase, resulting in a terrain impact. Post-impact examination revealed no mechanical anomalies, but the cabin door was found open at the time of the crash.
What happened
During the initial climb phase of flight, the airplane lost controlled flight characteristics and rolled inverted before impacting the ground. The sequence of events occurred rapidly during the early stages of ascent.
The investigation
A post-impact examination of the wreckage was conducted to determine the cause of the accident. The inspection failed to reveal any mechanical failures or pilot anomalies that would explain the loss of control. However, physical evidence on the airframe indicated that the cockpit and cabin door was open at the time of impact, as evidenced by scratches and a lack of damage to the latching mechanisms.
Findings
The investigation determined that the primary factor contributing to the accident was the open cabin door during flight. The mechanical systems of the aircraft functioned normally up until the point of impact.
Probable cause
The pilot's failure to ensure the cabin door was properly latched, which resulted in a loss of control during the initial climb.