What was found
LGW - FLT 721 - DURING CLIMB, SHUT DOWN NR 4 ENGINE, SN 4103, DUE TO OIL FILTER BYPASS LIGHT ILLUMINATING. FOUND OIL AND OIL FILTER HIGHLY CARBONATED. REPLACED ENGINE, SN 4103. ENGINE OPERATION CHECKED NORMAL. CHECK C-1 - 11-14-94 - JFK. SUPPLEMENTAL DATA - INVESTIGATION OF NR 4 ENGINE, SN 4103, OIL FILTER BYPASS LIGHT ILLUMINATION REVEALED NR 3 BEARING TUBE ASSY LEAKING AT THE JOINT ALLOWING CARBON THAT HAD BUILT UP IN THE NR 3 BEARING COMPARTMENT TO MIGRATE TO THE FILTER CAUSING THE BYPASS INDICATION. ENGINE, SN 4103, REPAIRED AND RETURNED TO SERVICE.