As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT NR 0679 - EWR - WHILE OPERATING THE APU, WITH THE NR 1 GENERATOR PLACARDED INOPERATIVE. THE APU GENERATOR FEEDER FAULT LIGHT ILLUMINATED. THE AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE APU GENERATOR CONTROL UNIT AT FAULT. THE APU GENERATOR CONTROL UNIT WAS REMOVED AND REPLACED. (W)