As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER SWITCHING ATT/HDG FROM NORM TO (2) AT 31000, BOTH CAPT AND F/O AHRS WENT BLANK. A/P KICKED OFF AND YAW NR 2 DISENGAGED SWITCHED TO NORM AND CAPT AHRS CAME BACK. THEN 5 SECS LATER F/O AHRS CAME BACK. REENGAGED A/P AND YAW DAMP, TO FURTHER PROBLEM. REMOVED AND REPLACED AHRS NR2 COMPUTER IAW 34-21-01, OPS CHECK GOOD.