What was found
(CAN) BA SER CASE: 44190 `AS PER TC AND CSALP AGREEMENT, A SDR MUST BE CREATED FOR EACH ETOPS EVENT` SER - ETOPS - ELECTRICAL AC BUS 1 AND 2 ISSUES EVENT #1: DLY/CS100/SN 50023/AIRPORT: BOS - STATUS: EVENT DID NOT RESULT IN OOS STATUS/24 - ELECTRICAL POWER/COMMENTS: ELECTRICAL AC BUS 1 AND 2 ISSUES, DELAY 7H50 MIN EVENT #1 AC POWER BUS 1 & 2 ISSUES. O WHILE AIRCRAFT POWER WITH EXT POWER, AC BUS 2 NOT SUPPLIED, O WHILE AIRCRAFT POWER WITH APU POWER, AC BUS 1 NOT SUPPLIED, O WHILE AIRCRAFT POWER WITH EXT AND APU POWER, ALL BUSSES NORMAL, O FAULT CODE 2451F0010 (BTC3 FAIL), O BTC3 REPLACED, NIL FIX, O BTC3 AND BTC2 SWAPPED, NIL FIX, O BPCU1 AND 2 SWAPPED, NIL FIX, O ACTION PLAN PROVIDED FOR WIRING CHECK TO XXXXX MAINTENANCE DIDN`T WANT TO DO THE WIRING CHECK, SO THEY REPLACED THE BPCU2 (BUS POWER CONTROL UNIT) AND THE FAULT DISAPPEAR. O AIRCRAFT RTS AFTER A DELAY OF 7H50MIN (PART). (TC# 20190422011)