As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF, CREW HEARD LOUD NOISE. DISCOVERED OVERHEAD EMERGENCY EXIT HATCH LEAKING EXCESSIVELY. RETURNED TO AIRFIELD, LANDING NORMAL. MAINTENANCE FOUND NUT MISSING FROM EMERGENCY ESCAPE HATCH LATCH HANDLE AND BOLT LOOSE. REINSTALLED BOLT AND NUT IAW B747 STD. PRACTICES. PERFORMED CHECK OF PRESSURIZATION SYSTEM IAW B747 MM 21-31-00. NO LEAKS NOTED. AIRCRAFT RETURNED TO SERVICE.