Locknuts
Locknuts are hex nuts with a built-in locking feature that holds them in place under vibration. They come in two main types. Nonmetallic insert locknuts use a nylon ring that grips the bolt threads. All-metal locknuts use a deformed top section that creates friction on the threads and handles higher temperatures. Monroe Aerospace stocks MS21044 nylon insert locknuts, MS21045 all-metal locknuts rated to 450°F, MS21046 locknuts, and NAS679 low-height locknuts. MS21044 is available in cadmium-plated steel (N), corrosion-resistant steel (C), and aluminum (D).
Elastic stop nuts shouldn't be installed where temperatures exceed 250°F. Learn the reuse and temperature limits for locknuts in Monroe's nut guide. Pair locknuts with the right flat washers to protect the surface and spread the load.
