As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE PILOT REPORTED THAT WHEN USING THE FLAP HANDLE TO EXTEND THE FLAPS SHE HEARD A LOUD BANG. THE ACFT LANDED WITHOUT INCIDENT. THE PILOT ALSO REPORTED THE THE FLAPS WENT TO THE FULL EXTENSION POSITION AFTER LANDING. WHILE INSPECTING THE FLAP SYSTEM AFTER THE FLIGHT, THE FLAP CONTROL RETURN SPRING WAS FOUND BROKEN OFF ON FWD HOOK END. THE FLAP RETURN SPRING WAS REPLACED AND THE SYSTEM WORKED NORMALLY. PROBABLE CAUSE, POSSIBLY A DEFECTIVE SPRING?