As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB THE FLIGHT CREW GOT A MESSAGE ON EICAS "RUDDER SYSTEM 1 & 2 INOP" "YAW DAMPENER INOP". AIRCRAFT RETURNED TO IAD. MAINTENANCE INSPECTED AND SWAPPED RUDDER PRESSURE SWITCHES NR 1 WITH NR 2 FOR TROUBLESHOOTING AND THEN REMOVED AND REPLACED NR 1 PRESSURE SWITCH. MAINTENANCE PERFORMED A LEAK AND OPS CHECK OF THE AUTO PILOT AND YAW DAMPENER SYSTEMS. OPS AND LEAK CHECKS WERE GOOD.