As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 5657 APU FAULT CAUTION AND APU SHUTDOWN AT GATE. THIS WAS ACCOMPANIED BY A BURNING ODOR. CORRECTIVE ACTION: BITE TEST OF APU SHOWS AUTO SHUTDOWN FOR HIGH OIL TEMP. REPLACED OIL COOLER BY-PASS VALVE PER B-757 AMM 49-27. FOUND AIR INLET DUCT FOR OIL COOLER COLLAPSED INTERNALLY. REPLACED APU OIL COOLER SUPPLY DUCT- APU OPN NML. (6917476)