As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, THE LT ENGINE INBOARD COWLING DOOR CAME OPEN. AN EMERGENCY WAS DECLARED. THE AIRCRAFT RETURNED AND LANDED SAFELY. C/A: MAINTENANCE REMOVED AND REPLACED THE COWLING DOOR AND UPPER COWLING. NO ADDITIONAL PARTS OR REPAIRS WERE NECESSARY. OPERATIONAL CHECKS GOOD. AIRCRAFT OK FOR SERVICE.