What was found
ON ARRIVAL RECEIVED LEVEL 1 BUS AC 3 OFF. WORKING CHECKLIST WITH OTHER ASSOCIATED ALERTS. EMERGENCY DECLARED. NO REFERENCE REQUIRED, CHECKED EPCU CURRENT FAULTS & FOUND AC BUSS-3 SENSOR RELAY INTERFACE SAME FAULT LISTED IN LAST LEG OF HISTORY. COMPLIED WITH STEPS 1 - 4. ON STEP 1 HAD CURRENT AC BUSS 3 SENSOR RELAY INTERFACE FAULT ON EPC. PERFORMED FIM STEPS, FOUND WIRING GOOD & NR 3 GCU BAD CONFIRMED WITH SWAPING WITH NR 2 GCU. GCU S PLACED BACK ORIGINAL & #3 CHANGED. ACCOMPLISHED NR 3 & 2 ENG RUN. ALL IND'S NORMAL. SWAPPED BETWEEN APU/EXT POWER & ENG POWER. ALL RESPECTIVE TIES OPENED & CLOSED. BUSS AC3 OFF ALERT REMAINED EXTINGUISED. ALSO NOTED NO CURRENT FAULTS IN EPCU. A/C OK FOR SERVICE.