Self Clinching Nuts
Self-locking nuts stay tight on a bolt or screw without a cotter pin, safety wire, or separate lock washer. The locking action comes from either a nonmetallic (fiber or nylon) insert or an all-metal section that grips the threads, keeping the nut from backing off under vibration. Monroe Aerospace stocks MS21042 reduced-hex all-metal nuts, MS21043 nuts, AN364 thin elastic stop nuts, NAS1291 thin-wall high-strength nuts, and NAS1804 and NAS1805 12-point extended washer nuts.
Temperature is the first thing to check. Nonmetallic insert nuts are generally limited to 250°F, while all-metal nuts are used in hotter areas. All-metal and fiber-lock self-locking nuts work differently. See how they compare, including Boots nuts, in our guide to aircraft nuts. For full-height hex styles like MS21044 and MS21045, shop our locknuts.
