As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT IN FLIGHT AT FL270 THEY RECEIVED A ATT & HDG FAIL ON PILOTS PDF & FMS HAD AHRS 1 INPUT FAIL, AHRS HDG FAIL MASSAGES. TROUBLESHOOTING FOUND THE NR 1 AHRS DEFECTIVE, THE DEFECTIVE UNIT PN 142185-1100 SN 1135 WAS REMOVED & A REPAIRED UNIT WAS INSTALLED.