As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING AN OIL CHANGE, THE MECHANIC NOTICED A BOLT WITH A SECURE NUT PROTRUDING FORWARD FROM THE BASE OF THE ALTERNATOR. A CLOSER LOOK INDICATED THE HEAD OF THE ALTERNATOR MOUNT BOLT HAD SEPARATED FROM THE SHANK ALLOWING THE BOLT TO VIBRATE FORWARD TOWARD THE STARTER FLYWHEEL. REPLACED BOLT WITH NEW PART AND SECURED. TACHOMETER: 484.8. HOBBS: 181.8.