What was found
R1 GENERATOR, RT ENGINE. IAW NON NORMAL APU STARTED AND POWERED UP, IN APPROX 5 MIN APU LT GEN FAILED. F/A REPORTED A LOUD BANG FROM UNDER FLOOR IN THE AREA OF DOOR 3L. THIS IS CONTINUED ON LOG PAGE 7090676 TROUBLESHOT WIRING IAW ASSOCIATED FAULT CODES AND FIM TASKS, FOUND BAD R1 BUSS TIE BREAKER, BTB, CURRENT TRANSFORMER, CT, WITH LOW RESISTANCE. FLASH MARK BEHIND P200. ON FURTHER INSPECTION BELOW RIGHT GCU SLOT FAULT DATA.