What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
During the examination of the airplane wreckage, the investigative team found that the clamp nut that attaches the top eye end and bearing assembly of the horizontal stabilizer actuator to the actuator barrel (jack trim) had unscrewed from the barrel. The examination also found that the circular wire lock ring, which was designed to prevent the clamp nut from unscrewing, was not present. If the actuator barrel and the clamp nut are not secured together and become separated, the actuator would not be able to control the position of the horizontal stabilizer, resulting in a reduction or loss of pitch control.
As the FAA filed it
DURING THE EXAMINATION OF THE AIRPLANE WRECKAGE, THE INVESTIGATIVE TEAM FOUND THAT THE CLAMP NUT THAT ATTACHES THE TOP EYE END AND BEARING ASSEMBLY OF THE HORIZONTAL STABILIZER ACTUATOR TO THE ACTUATOR BARREL (JACK TRIM) HAD UNSCREWED FROM THE BARREL. THE EXAMINATION ALSO FOUND THAT THE CIRCULAR WIRE LOCK RING, WHICH WAS DESIGNED TO PREVENT THE CLAMP NUT FROM UNSCREWING, WAS NOT PRESENT. IF THE ACTUATOR BARREL AND THE CLAMP NUT ARE NOT SECURED TOGETHER AND BECOME SEPARATED, THE ACTUATOR WOULD NOT BE ABLE TO CONTROL THE POSITION OF THE HORIZONTAL STABILIZER, RESULTING IN A REDUCTION OR LOSS OF PITCH CONTROL.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.