THE PLT OF A C310 HAS THE R ENG START VIBRATING VIOLENTLY WHEN ITS BLOCK SPLITS. THE PLT DOES NOT DECLARE AN EMER; BUT THE PVD APCH CTLR PROVIDES VECTORS TO THE NEAREST ARPT; TO WHERE THE ACFT IS SAFELY LANDED.

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I WAS PIC OF A C310R ON AN IFR FLT PLAN FROM MVY TO N87 AT 6000 FT WITH 5 PAX. I WAS 400 LBS UNDER MAX GROSS WT AND WITHIN CTR OF GRAVITY LIMITS. THE ACFT HAD ITS ANNUAL DONE APPROX 4 HRS PRIOR TO THIS FLT. WHILE OVERWATER AND PERHAPS 3 MI FROM THE COAST OF LONG ISLAND THE R ENG SUDDENLY BEGAN SHAKING VIOLENTLY AND SPEWING OIL THROUGH ITS VENTS AND COWLING SIDE. ALL GAUGES SHOWED NORMAL PRESSURE AND TEMP FOR OIL. PWR WAS BEING LOST AND SHAKING GREW WORSE. I DECIDED TO SHUT DOWN AND FEATHER R ENG/PROP. I NOTIFIED PROVIDENCE APCH THAT I WAS AMENDING MY DEST; THAT I WAS FORCED TO SHUT DOWN MY R ENG AND ASKED FOR THE NEAREST ARPT AND TERMINAL CONDITIONS. I DID NOT DECLARE AN EMER; NOR DID I ASK FOR PRIORITY HANDLING. APCH ASKED ME IF I WANTED TO DECLARE AND I SAID NO. I CHOSE EAST HAMPTON ARPT SINCE ITS CEILING WAS THE HIGHEST AROUND LONG ISLAND AT 1000 FT OVCST AND IT WAS THE CLOSEST. I CHOSE THE VOR A APCH RWY 10 WHERE I CIRCLED TO LAND ON RWY 28. THERE WAS A FALCON JET THERE HOLDING SHORT WHO WAS RELAYING CONDITIONS TO APCH FOR ME. WINDS WERE 200 DEGS AT 8 KTS. I LANDED UNEVENTFULLY ON RWY 28 ALTHOUGH I OVERSHOT MY BASE LEG AND IT AFFECTED MY TURNS TO FINAL ON THE L ENG. LNDG WAS NORMAL -- NO DAMAGE; NO INJURIES AND PAX WERE FAMILY AND DID FINE. IT TURNED OUT THAT THE R ENG HAD A CATASTROPHIC FAILURE -- THE BLOCK SPLIT AND TORE OFF THE L REAR CYLINDER AND THREW OUT THE BOLTS HOLDING THE OIL SUMP. IF I HADN'T FEATHERED THEM WHEN I DID THE ENG MAY HAVE SEIZED AND LEFT ME WITH A WINDMILLING PROP. THE ENG WHICH FAILED WAS ABOUT 200 HRS FROM TBO. EVEN AFTER A THOROUGH ANNUAL WITH GOOD COMPRESSION AN ENG CAN HAVE A CATASTROPHIC FAILURE. THIS WILL ALWAYS MAKE ME RETHINK TBO TIME AND CONSIDER EARLY OVERHAULS. FURTHERMORE; THE DECISION TO SHUT DOWN AND FEATHER AN ENG EVEN IN ADVERSE CONDITIONS MUST BE EXPEDITIOUS. STAY CURRENT; STAY PROFICIENT; AND BE ABLE TO MAKE DECISIONS -- THAT'S MY MORAL FOR THE OTHER PICS. I NOTIFIED APCH ON LNDG THAT ALL WAS WELL AND THANKED THE FALCON PLT.