As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW WENT TO INSTALL A WING BOLT RETAINING NUT ON THE AIRCRAFT. IT WAS NOTICED THAT THE NUT WAS MISSING ONE OF THE TWO PLASTIC LOCKING DEVICES. IT APPEARS THE PLASTIC WAS NEVER INSTALLED IN ONE HOLE. THIS IS THE SECOND NUT THAT WAS FOUND WITH PROBLEMS. PREVIOUSLY ANOTHER NUT HAD BAD THREADS IN IT EVEN THOUGH IT WAS NEW.