As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, THE CAPTAINS AHRS FAILED CAUSING THE ADI AND HSI TO TUMBLE. BOTH F/DS BECAME INOPERATIVE. SAHS WAS SELECTED AND A SLIGHT MISMATCH WAS NOTED. AN AIR TURNBACK WAS PERFORMED BUT NO EMERGENCY WAS DECLARED. UPON RETURN TO FIELD, MAINTENANCE REPLACED THE NR 1 AHRS COMPUTER. OPS CHECKS WERE GOOD AT THAT TIME AND THE AIRCRAFT WAS RETURNED TO SERVICE.