What was found
AFTER TAKEOFF, AIRCRAFT FISHTAILED (YAW LEFT TO RIGHT) RETURNED BACK TO KCVG,(ATB) AND DECLARED EMERGENCY.PERFORMED A SMOOTH OVERWEIGHT LANDING AT 305,000 LBS. ADDITIONAL "R YAW DAMPER" CAUTION AT FINAL APPROACH . MTX GROUNDED A/C ,TROUBLE SHOT AND REPLACED RIGHT YAW DAMPER SERVO, M509, PER B767 AMM 22-21-02. SYSTEM CHECKS NORMAL. OVERWEIGHT INSPECTION TRANSFERRED TO ITEM 38994-33/2. PERFORMED PHASE 1A OVERWEIGHT LANDING INSPECTION IAW AMM 05-51-35. NO DEFECTS NOTED MTX RETURNED A/C TO SERVICE.