Unapproved Parts Notice (UPN) Issued Against Barrel Nuts, P/N NAS577B7A

The FAA has issued a new Unapproved Parts Notice (UPN) concerning Barrel Nuts, part number NAS577B7A produced by Alcoa Fastening Systems.  The UPN applies only to Batch Numbers 5334992-000, M004187-000 and 5323292-000.

The FAA issued an emergency airworthiness directive in July to the owners and operators of Embraer EMB-500 aircraft; this was issued in response to a Brazilian airworthiness directive.  The Brazilian airworthiness directive was issued in order to promote the detection and correction of cracking in the barrel nuts.  Crackig had been detected at the horizontal stabilizer-to-vertical stabilizer attachment joint.

The emergency AD was not sent to distributors who might have had these parts in their inventories, so a follow-up AD was published in the Federal Register in August.  Because UPNs are typically aimed at products and not parts, an UPN was issued today to ensure that the remainder of the aviation community received notice about these parts.

The UPN advises companies to perform a close visual inspection for surface irregularities, such as gouges or cracks, before installing these nuts on an aircraft.  It advises the industry to quarantine suspect parts until conformity to the manufacturing standard can be verified.  The UPN notes that some non-conformities may not be visible during visual inspection, so companies should use their quality acceptance criteria to help identify parts that must be subject to additional scrutiny.