What was found
ACFT SUDDENLY STARTED TO YAW SHARPLY, BOTH LT & RT BALL DEFLECTED FULL SCALE IN SLIP INDICATOR. DESCENT TO FL300 & SPEED REDUCTION TO .78 MACH, TURNING OFF AUTOPILOT HELPED. YAWING STOPPED. TROUBLESHOT IAW FIM 22-21-00. FOUND LT YAW DAMPER SYSTEM FAULTED. LVDT FAULT BALL ON YAW DAMPER MODULE. LEFT YAW DAMPER SERVO REMOVED IAW AMM 22-21-02-024-057. GVI OF AIRFRAME & HARDWARE. NO DEFECTS NOTED. INSTALLED LT YAW DAMPER IAW MM 22-21-02-424-017. EFF SOURCE IPC 22-21-02-01, ITEM 010.