As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LEFT ENGINE GENERATOR FAILED IN FLIGHT AND APU WOULD NOT START IN FLIGHT. APU WAS STARTED ON THE GROUND. THE AIRCRAFT WAS GROUNDED. MAINTENANCE ACCOMPLISHED APU BITE TEST IAW TSM 49-815-846-0-01 WITH NO FAULTS NOTED. MAINTENANCE ALSO REPLACED THE NR 1 GENERATOR CONTROL UNIT (GCU) AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK IAW AMM 24-22-02.