As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING APPROACH TO LAND, PILOT EXPERIENCED A LOUD CONTINUOUS NOISE COMING FROM THE ENGINE. ALL ENGINE INSTRUMENTS WERE NORMAL. ENGINE WAS INSPECTED BY MAINT, NO OBVIOUS MALFUNCTIONS WERE NOTED. DURING ENGINE RUN-UP TO ISOLATE ENGINE NOISE, THE ENGINE CHIP DETECTOR CAUTION LIGHT ILLUMINATED. CHROME SLIVERS WERE FOUND ON BOTTOM PLUG. TEAR-DOWN INSPECTION, FOUND NR 1 TURBINE WHEEL BLADE MISSING AND OTHER BLADES DAMAGED. (X)