As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENG VIBRATION AFTER TAKEOFF. A/I EMERGENCY DECLARED. IN FLIGHT AIRFRAME BEGAN TO SHAKE/VIBRATE. NO ENGINE VIBRATION NOTED. CLEAN CONFIGURATION. NO OVERWEIGHT LANDING. NO EXCESSIVE SINK RATE ON LANDING. UPON POST FLIGHT INSPECTION FOUND E1 PRE-COOLER EXHAUSE PANEL WAS FOUND PEELING BACK.