As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED LOUD SQUEAL FROM MAIN CABIN DOOR IN FLIGHT. CREW RETURNED TO FIELD AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED, REMOVED DEBRIS FROM PASSENGER DOOR SEAL AREA AND PRESSURIZED ACFT IAW AMM. NO DEFECTS NOTED. ACFT RELEASED FOR SERVICE.