As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT 2391 A/C N13970 AIR RETURN FROM EWR-"ON THE CLIMBOUT LOST TWICE ATT AND HDG ON CPT SIDE. MAINTENANCE REMOVED AND REPLACED NR 1 AHRS COMPUTER 800 SERIES AND OPERATIONAL CHECK GOOD IAW 34-21-01 AND OPS CHECK GOOD IAW 34-21-00. RETURN TO CAT II. THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.