Aircraft owners, operators, manufacturers, maintenance organizations, parts suppliers and distributors were notified on November 14 to be on the alert for Alcoa Fastening Systems barrel nuts numbered PN NAS577B7A, batch numbers 5334992-000, M004187-000 or 5323292-000. Users are asked to inspect them carefully for gouges or cracks, before installing these parts. Suspect parts should be quarantined until conformity to the manufacturing standard is verified.