As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RIGHT FUEL TANK CRACKED ON TOP SEAM. TANK WAS REPLACED. OPERATOR NOTICED A VERY LOUD OIL CANNING SOUND FROM RT WING AFTER SHUTDOWN FOLLOWING A 1 HOUR FLIGHT. FURTHER INVESTIGATION FOUND A PARTIAL BLOCKAGE OF FUEL TANK VENT CAUSING OIL CANNING OF FUEL TANK DUE TO VACUUM IN FUEL TANK. VENT LINE WAS CLEARED AND VENTED CAP WAS REPLACED WITH NEW.