As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER COMPLETION OF THE ENGINE 150 HOUR INSPECTION, A GROUND RUN WAS ACCOMPLISHED. DURING THE GROUND RUN AN UNUSUAL NOISE WAS HEARD, DESCRIBED AS A ANGRY VACUUM CLEANER. THE ENGINE CHIP PLUGS WERE PULLED AND A SIGNIFICANT AMOUNT OF METAL WAS FOUND ON THEM.