As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED UNUSUAL NOISE COMING FROM LT ENGINE. TECH INVESTIGATED AND COULD NOT DETERMINE SOURCE OF NOISE. DECISION WAS MADE TO REMOVE ENGINE AND SEND TO ENGINE SHOP FOR FURTHER TEAR DOWN AND EVALUATION. ENGINE SHOP FOUND ENGINE THRU BOLT LOOSE.