As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT THE STANDBY ATTITUDE INDICATOR PRECESSING IN SMOOTH AIR LEVEL FLIGHT 20 DEGREES NOSE DOWN AND 19 DEGREES BANK AFTER 28 MINS IN FLIGHT. THE MAINTENANCE TEAM DETERMINED THAT THE STANDBY ATTITUDE INDICATOR WAS DEFECTIVE AND WAS REPLACED WITH A REPAIRED UNIT. OPS CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS THEN RETURNED TO SERVICE .