What was found
ENGINE WAS RETURNED FOR HIGH VIBRATION/NOISE. DURING FLIGHT, REPORTED A NOISE AND VIBRATION IN THE CABIN. FIELD TROUBLESHOOTING COULD NOT IDENTIFY THE ISSUE. THE 1E LP VIBRATION WAS MEASURE AT 1.5 -1.75 IPS. UPON RECEIPT IN THE REPAIR STATION THE ENGINE WAS BORESCOPE INSPECTED WITH NO FINDINGS. THE AS RECEIVED RUN CONFIRMED THE HIGH 1ELP VIBRATION. UPON DISASSEMBLY, ONE OF THE NR1 BEARING HOUSING BOLTS AT THE 6 O’CLOCK POSITION HAD COME LOOSE AND STUCK TO THE INSIDE DIAMETER OF THE IP ROTOR DRUM. COKED OIL CAUSED THE BOLT TO STICK TO THE ROTOR.