As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT DURING FLIGHT WHILE PRESSURIZED 7.5 PSI A LOUD UNIDENTIFIED NOISE IS IN THE CABIN. THE MAINTENANCE VENDOR PERFORMED GROUND PRESSURIZATION RUN AND FOUND AIR LEAKING FROM UPPER ADF ANTENNA. A NEW GASKET WAS INSTALLED. LEAK CHECKS SATISFACTORY. THE AIRCRAFT WAS THEN RETURNED TO SERVICE.