SAIB for Non-Conforming Fasteners (MS, AN, NAS)

On June 2, the FAA issued a revised Special Airworthiness Information Bulletin (SAIB) addressing concerns with potential non-conforming fasteners, including Military Specifications (MS), Army-Navy Standards (AN), and National Aerospace Standards (NAS). The SAIB was issued in response to reports of cracking and manufacturing defects.

The FAA recommends that all manufacturers, aircraft owners, operators, and maintenance personnel find and remove any non-conforming MS 21042 nuts from service, as well as torque checks on all incoming lots of new self-locking nuts. The FAA also requests reports of fastener failures and other non-conformities. SAIBs encourage industry awareness, inspection, and reporting, but are not mandatory to comply with.