As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED HIGH PITCHED NOISE IN FLIGHT AFTER TAKEOFF. CREW ELECTED TO RETURN TO CLT LANDING WITHOUT INCIDENT. MAINTENANCE INSPECTED AND FOUND THE MAINTENANCE SERVICE DOOR OPEN. MAINTENANCE INSPECTED AND SECURED THE DOOR WITH NO DEFECTS. AIRCRAFT WAS RELEASED FOR SERVICE. (A)