What was found
DURING A RECENT FLIGHT, AT A POINT APPROXIMATELY 100 NM SW OF DESTINATION AND AT AN ALTITUDE OF 28,000 FT, THE NR 2 ENGINE OIL FILTER BYPASS LIGHT ILLUMINATED. THE CREW REDUCED THRUST TO ABOUT 70 PERCENT N1 AND THE LIGHT BENT OUT. THE NR 2 OIL FILTER BYPASS LIGHT THEN CAME BACK ON. THE THROTTLE WAS THEN PLACED TO IDLE AND ABNORMAL SHUTDOWN PROCEDURES WERE FOLLOWED. AN EMERGENCY WAS DECLARED AND THE ACFT LANDED SAFELY WITHOUT INCIDENT. UPON INSPECTION OF THE NR 2 ENGINE, IJW MAINTENANCE FOUND THE THERMAL ANTI-ICE TUBE BROKEN AND SOME CARBON BUILD-UP IN THE MAIN OIL FILTER. BOTH THE ANTI-ICE TUBE AND OIL FILTER WERE CHANGED ALONG WITH THE OIL FILTER BYPASS SWITCH. THE ENGINE WAS RAN TO ENSURE THAT NO FAULTS WERE STILL PRESENT IN THE OIL FILTER BYPASS WARNING SYSTEM, NONE WERE NOTED AND THE ACFT WAS RETURNED BACK TO SERVICE.