What was found
ABOUT 30 MIN INTO FLIGHT, GEN 1 OFF FLASHED ON MOMENTARTLY. ABOUT 20 MIN LATER THE GEN 1 OFF & GEN 2 OFF & GEN 3 OFF FLASHED ON AND OFF CONTINUOUSLY FOR REMAINDER OF FLIGHT. ALL TIE BUSSES OPENED WHEN THE GEN OFF LIGHTS CAME ON. ACCESSED EPCU THRU CFDS AND FOUND FAULTS PRESENT LAST 2 FLIGHT LEGS. LEG -1 FAULT WAS GCU-2 WIRE INTACT GCU/TR-2B, FAULT ALSO LISTED IN-AIR FLT 0440, FAULT LEG 2 WAS GCU-2. REMOVED AND REPLACED THE EPCU IAW MM 24-08-01-4. PERFORMED ELECTRICAL POWER CONTROL ADJ/TEST IAW MM 24-08-01-5, ALL INDICATIONS NORMAL. RAN ALL ENGINES AND APPLIED MAX LOAD WITH EXTERIOR LIGHTS AUX HYD PUMPS AND FUEL PUMPS ON. VERIFIED THAT EACH ENGINE GENERATOR WOULD POWER THE ACFT INDIVIDUALLY. ENGINES RAN IAW JRH CHAPTER 5. ALL INDICATIONS NORMAL. AFTER REPLACEMENT OF THE EPCU, PERFORMED REQUIRED FCC-1 AND FCC-2 AFS TESTS TO MAINTAIN ACFT LLM CAPABILITY. ALL AFS TESTS PASSED ACFT REMAINS LLM CAPABLE.