What happened
A witness located northeast of the accident site observed the aircraft initiating a vertical climb, followed by a slow roll and a direct dive toward the ground. According to the witness, the aircraft made no apparent attempt to recover from the dive. The aircraft disappeared behind a mountain, after which the sound of impact was heard.
The investigation
Examination of the wreckage identified a screwdriver located in the aft section of the fuselage. Investigators noted multiple witness marks around the elevator bellcrank housing and numerous gouges on the screwdriver itself. Testing revealed that when the screwdriver was positioned between the elevator bellcrank and its housing, manual movement of the bellcrank restricted the elevator control to the neutral position. Energy dispersive x-ray spectroscopy analysis confirmed that the screwdriver had been lodged between various structural components.