What was found
LIM - FLT 918 - EN ROUTE LIM-MIA, DURING CLIMB-OUT DETECTED RUDDER VIBRATION. VIBRATION INCREASED AFTER TURNING OFF AUTOPILOT. RETURNED LIM AND LANDED WITHOUT FURTHER INCIDENT. ACCOMPLISHED RUDDER ATTACHMENT INSPECTION AND VERTICAL STABILIZER ATTACHMENT INSPECTION. ALL FOUND NORMAL. REPLACD YAW DAMPER ACTUATOR AND BOTH FLIGHT AUGMENTATION COMPUTERS. ACCOMPLISHED OPERATIONAL CHECK OF YAW DAMPER SYSTEM AND AUTO PILOT SYSTEM. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)