As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIT FLT414 FLIGHT DEPARTED ORD, EN ROUTE TO PHL, WITH THE NR 2 GENERATOR ON MEL 24-1. DURING CRUISE, THE APU GENERATOR DROPPED OFF LINE, LEAVING ONLY THE NR 1 GENERATOR. FLIGHT DIVERTED TO PIT AND LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED. MAINTENANCE ACCOMPLISHED APU PERFORMANCE CHECK CARD J3-049. ALL PARAMETERS WITHIN MAINTENANCE MANUAL LIMITS. REMOVED AND REPLACED APU GENERATOR CONTROL UNIT (GCU), AS PRECAUTIONARY, PER MM 24-21-81-4. GENERATOR NR 2 REMAINS ON MEL 24-1.