As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING RUN UP, YAW SAS AND BACK UP SAS CAUTION SEGMENT LIGHTS ILLUMINATED, SHOWING BOTH SYSTEMS OFF LINE. AVIONIC PERSONNEL WERE CALLED BUT COULD NOT GET EITHER SYSTEM TO COME BACK ON LINE. REMOVED AND REPLACED FOG GYRO IAW AMM 22-10-00, 4-5. TEST FLILGHT COMPLETED IAW AMM 05-60-00, 6-12.