What was found
ENGINE CHIP LIGHT, DURING FLIGHT, PILOT HEARD INCREASING "RUMBLING" NOISE. LANDED TO THE NEAREST LANDABLE SITE, APPROX 2 MIN AFTER THE NOISE STARTED. RUMBLING DECREASED SIMULTANEOUSLY WITH ENGINE LOAD. ENGINE CHIP CAUTION ILLUMINATED AT THE END. AFTER REMOVAL OF MODULES FROM THE ENGINE, FUND THAT THE BEARING 2.5 FAILED. DRIVESHAFT BETWEEN GP ROTOR AND COMPRESSOR ARE RUBBING AGAINST THE SHORT DRIVE SHAFT EDGE. ALL GEARBOX BEARINGS INSPECTED. BEARING NR 5 IN THE TURBINE CHECKED AS WELL AS BEARING NR 1 AND NR 2 IN THE COMPRESSOR AND BEEN APPROVED. COMPRESSOR HSG PLASTIC COATING HAS STARTED TO SEPARATE AND RISEN FROM THE COMPRESSOR HSG. BOTH ENGINE MAGNETIC PLUGS WERE CHECKED. PASTE AND SMALL SILVER PARTICLES, NO EXCEEDING 0.79 MM WERE FOUND ON UPPER AND LOWER PLUGS (RR OPERATION ADN MM 72-00-00 11.G)