What happened
While approaching the destination airport, the pilot experienced a sudden event that disrupted normal flight operations. He reported hearing a loud bang, immediately followed by an uncommanded roll to the right. Standard control inputs via the ailerons proved ineffective in counteracting this motion.
To regain stability, the pilot reduced power on the left engine and applied left rudder pressure. These corrective actions allowed the crew to maintain directional control of the aircraft. They successfully completed the approach and executed a safe landing without further incident.
The investigation
Post-flight inspection revealed significant damage to the flight control surfaces. The left aileron was found to be bent at the second hinge point. Further examination uncovered the root cause: on February 20, 1984, the screws securing the outboard hinge of the left aileron were improperly installed.
This maintenance error allowed the outboard section of the aileron to become loose during flight. The structural failure resulted in the loss of roll control authority that the pilot encountered during the arrival phase.