What was found
DURING APPROACH, RUDDER BOUND AND WOULDN'T MOVE TO THE LT WITH NORMAL RUDDER PEDAL FORCE. WHEN MORE RUDDER PEDAL FORCE WAS APPLIED THE RUDDER SUDDENLY "BROKE LOOSE" AND YAWED HARD TO THE LT. HAPPENED ONCE MORE TO THE RT. USED RUDDER TRIM FOR THE REMAINDER OF THE FLIGHT AS SUGGESTED BY FCIF. LANDING UNEVENTFUL. C/W GVI OF ENTIRE RUDDER CONTROL SYS, C/W RUD CTL SYS OPS CHECK, C/W FREEDOM OF MOVEMENT CHECK, REPLACED FDR, NO DEFECTS NOTED. FERRIE FOR REPAIRS. R & R RUDDER FELL/ TRIM / SUM UNIT IAW AMM 27-22-06-000-801 AND 27-22-06-400-801. OPS CHECK FLIGHT OK. RETURNED TO SERVICE.