As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLT - FLT528 - THIRTY MINUTES AFTER TAKEOFF FROM CLT, EN ROUTE TO MCI, THE FIRST OFFICERS ADI FAILED WITH INTERMITTENT FLAGS IN VIEW. CREW DECIDED TO RETURN TO FIELD AT CLT WHERE THE FLIGHT LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE FOUND THE NR 2 DIGITAL TO ANALOG CONVERTER (DAA) DEFECTIVE. REMOVED AND REPLACED THE DAA. ALSO, REMOVED AND REPLACED FIRST OFFICERS ADI. FUNCTIONAL TESTS GOOD.