What was found
(CAN) ACFT ENG SN 282949-R CRANKCASE FAILURE, 7TH STUD CRANKCASE, CRANKCASE FRETTING ON NR 2 & 3 INTERMEDIATE BEARING SADDLE THRU-BOLT PADS. WHEN THIS OCCURS, THE PINCH FIT IS LOST ON THE MAIN BEARINGS IN THESE POSITIONS & THEY BECOME LOOSE. AS A RESULT, THE BEARING TENDS TO SHUFFLE BACK & FORTH WITH THE THRUST OF THE CRANKSHAFT FWD & THEN BACK. IN THIS CASE, THE BEARING TANGS WERE WORN OFF DUE TO THIS MOVEMENT. THE MAIN BEARING IN THE NR 2 POSITION STARTED TO COME APART, ALLOWING THE OTHER HALF OF THE BEARING TO MOVE & RIDE UP INTO THE CRANKSHAFT RADIUS CREATING A STRESS RISER. THE CRANKSHAFT BROKE JUST IN THE FWD RADIUS BELOW NR 2 MAIN JOURNAL, RESULTING IN A CATASTROPHIC FAILURE OF THE ENG.