What was found
ON DESCENDING FROM FL 360 FT, A SMALL VIBRATION WAS FELT. ALL INDICATIONS NORMAL AND PILOT REPORTED THE VIBRATION WAS COMING FROM THE LT ENGINE. AT FL100 FT A MORE STEADY VIBRATION FELT. ALL ENGINE PARAMETERS REMAINED GREEN (NORMAL). NOTICED RT OIL PRESSURE LOWER THAN LT. RT OIL PRESSURE WAS 58 PSI & LT 78 PSI. ABOUT 20 MILES OUT, CABIN FILLED WITH SMOKE. OXYGEN MASKS WERE PUT ON BY PILOTS & AN EMERGENCY WAS DECLARED. LANDED UNEVENTFULLY. ALL ENGINE PARAMETERS REMAINED IN GREEN THROUGHOUT FLIGHT. SHUTDOWN ENGINES AFTER TAXI. POST-FLIGHT INSPECTION FOUND THE NO OIL IN SIGHT GLASS OF RT ENGINE. INSPECTION OF CHIP DETECTORS FOUND ALL 3 CHIP DETECTORS CONTAMINATED WITH METAL. ENGINE REMOVED. FOUND WEAR OF THE NR 2 BEARING THE ROOT CAUSE OF ANOMALY.