What was found
IN FLIGHT, ACTUATOR LIGHT CAME ON. DURING AP TROUBLESHOOTING, FOUND BAD YAW FOG GYRO. RECEIVED A YAW FOG FAIL, YAW FOG INVALID, AND YAW ARINC MESSAGE. VERIFIED ALL VOLTAGES WERE PRESENT AND GOOD AT THE YAW FOG GYRO. REMOVED AND REPLACED YAW FOG GYRO IAW AMM 22-10-00,4-5. MOC SUCCESSFULLY COMPLETED IAW AMM 22-10-00,5-1.