As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT, LEFT ENGINE GENERATOR DROPPED OFF LINE 3 TIMES. APU WAS NOT ON, ONLY LEFT ENG GENERATOR. PERFORMED BITE ON BPCU. NO FAULTS NOTED. NO HISTORY. REMOVED AND REPLACED LEFT ENG GCU. RAN LEFT ENG ONLY. NO APU. LOADED SYSTEM. NO FAULTS NOTED.