What was found
(CAN) CREW REPORTED THE NR 1 ENGINE OIL FILTER BYPASS INDICATION ILLUMINATED JUST PRIOR TO DECENT. INDICATION WOULD NOT EXTINGUISH WITH THRUST REDUCED RESULTING IN ENGINE BEING SHUTDOWN IAW FOM. EMERGENCY LANDING WAS REQUESTED AND THE ACFT LANDED UNEVENTFULLY. UPON INVESTIGATION BY MAINTENANCE IT WAS DISCOVERED THAT A SIGNIFICANT AMOUNT OF MAGNETIC MATERIAL HAD ACCUMULATED ON THE AGB MCD MAGNET. THE AGB WAS DETERMINED TO HAVE FAILED AND THE ENGINE WAS REPLACED.