Primary finding
Probable cause
The assigned mechanic's failure to reinstall the attachment screws and the quality inspector's inadequate inspection of the completed work. A factor was the complacency of the maintenance personnel.
Investigator assessment
Analysis narrative
Shortly after takeoff the first officer felt a vibration through the airframe and the control column. The captain felt the same vibration and elected to execute a precautionary landing at the departure airport. Investigation revealed that 14 screws were missing from the left upper aileron vane and that the screws had been left out after the vane was partially removed during maintenance prior to the flight. The assigned mechanic did not replace the screws and the quality control inspector failed to see that they were missing during his inspection.
Source record
Factual narrative
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