What was found
NR 2 ENGINE COMPRESSOR STALL FOLLOWED BY OIL FILTER CLOGGED MESSAGE. SHUTDOWN ENGINE. NR 4 MAINLINE ROLLER BEARING FAILED, CAUSING ENGINE TO AUTO-SHUTDOWN. NR 4 BEARING HAD 1417 FLT HOURS FROM LAST OVERHAUL. BEARING FAILURE CONFIRMED AS CAUSED BY BEARING CAGE FAILURE. CAGE FAILURE EXACT CAUSE UNKNOWN, HOWEVER BATCH ESCAPE DURING POST-PLATING BAKE PROCEDURE HEAVILY SUSPECTED TO HAVE CAUSED HYDROGEN EMBRITTLEMENT, LEADING TO EVENTUAL FRACTURE. NO FURTHER OVERHAULED NR 4 BEARINGS WITH RE-USED CAGES WILL BE ACCEPTED BY UAL.