What was found
DURING CLIMBOUT, CYAN YAW DAMPER FAIL UPPER A MESSAGE APPEARED. PFD WAS SELECTED TO RT SIDE AND UPPER RUDDER B WAS ILLUMINATED. MESSAGE STAYED ON FOR REMAINDER OF FLIGHT AND TAXI IN. COULD NOT DUPLICATE DISCREPANCY ON GROUND. PERFORMED YSAC SYS OPS CHECKS. FOUND NORMAL. CHECKED GROUNDS & RUDDER SURFACE POSITION SENSORS. FOUND TO BE NORMAL. REPOSITIONED YSAC A&B. PERFORMED YSAC SYSTEM TEST, ALL NORMAL. WORK DONE IAW MM 27-24-01. OPS CHECKED NORMAL.