As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION TYPE:N/A ON CLIMB WITH CABIN PRESSURE DIFFERENTIAL BETWEEN 1.5 - 3.5 PSI THERE WAS A LOUD AIR LEAK FROM CABIN DOOR AREA. NOISE LEVEL WAS SUCH THAT COCKPIT COMMUNICATIONS WERE LIMITED. ACCOMPLISHED AIR TURNBACK. REMOVED LOOSE SEALANT AT MAIN CARGO DOOR UPPER FORWARD SEAL AREA. RESEALED AND PRESSURIZED PER MM 21-31-00-2. NO LEAKS NOTED.