As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOTH NR 1 & NR 2 YAW DAMPERS WOULD NOT ENGAGE. AIRCRAFT RETURNED TO AIRFIELD. LANDING NORMAL. MX FOUND NR 1 & NR 2 YAW RATE GYRO'S AT FAULT. REMOVED AND REPLACED NR 1 & NR 2 YAW RATE GYROS IAW 22-21-45. OP'S CHECK SATISFACTORY. A/C RETURNED TO SERVICE.