As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ETOPS SIGNIFICANT SYSTEM, BTB, APU HAD AUTO SHUT DOWN FAULT LT ILLUMINATED. F/A HEARD UNUSUAL NOISE BEHIND AFT GALLEY. FOUND SURGE VALVE STUCK IN CLOSED POSITION REMOVED AND REPLACED SURGE CONTROL VALVE PER AMM 49-53-01, OPS CK OK. NO FAULTS NOTED APU OK TO CONTINUE.