What happened
Following takeoff, a Douglas MD82 experienced a significant flight control malfunction. The crew reported that the aircraft lost autopilot connectivity and experienced intermittent "kicks" on the rudder during the flight. Upon landing at Dulles International Airport, the crew observed that the rudder tab was moving uncommanded while the aircraft was on the ground.
The investigation
Investigators removed several components for laboratory testing, including the Yaw Damper Actuator, the Digital Flight Guidance Computer, and the Dual Axis Accelerometer. Testing confirmed that both the Yaw Damper Actuator and the Digital Flight Guidance Computer were functioning correctly.
The Dual Axis Accelerometer underwent bench testing at the avionics test center following test manual #22-19-01, Rev 1. The unit failed its initial test. A subsequent test was performed after a metal sliver was discovered embedded in the pins of the unit; however, the component failed the second test as well.