As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT FROM CRUISE ALTITUDE, CREW EXPERIENCED ENGINE VIBRATION ACCOMPANIED BY EEC MANUAL L ADVISORY WITH NO ENG VIB ANNUNCIATOR. THROTTLE AY IDLE ITT= 650. EEC CHECKLIST DID NOT EFFECT VIBRATION. PERFORMED PRECAUTIONARY S/D. VISUALLY INSPECTED CHIP DETECTOR AND OIL FILTER ON LH ENGINE. PERFORMED BOROSCOPE ON LH ENGINE COMPRESSOR AND HP TURBINE. INSTALLED MODIFIED BLEED VALVE TORQUE MOTOR ON LH ENGINE I.A.W. P&W MM 75-30-01. COMPLETED 5 POINT ENGINE PERFORMANCE RUN I.A.W. P&W MM 71-00-00. ALL CHECKS GOOD.