MS21042 'Style B'

Airfasco is now a licensed manufacturer of MS21042 'Style B' nuts. The MS21042 series is used throughout the aerospace industry and have gained a reputation for failure due to hydrogen assisted cracking. However, this is a misconception, the actual failure mode is due to nut dilation. We have worked closely with Inspec100 to become the first manufacturer of this revolutionary new design. In testing, Airfasco has found that these nuts are capable of meeting the same mechanical properties of conventional MS21042 nuts while having the lower HRC hardness requirements. This results in a nut that has a lower likelihood of cracking caused by nut dilation while still meeting all of the requirements of MS21042 procurement specifications.

Free samples and/or upgrades available on request.

MS21042 / NAS1291 Style B

All newly manufactured MS21042 nuts produced by Airfasco will be MS21042 'Style B' nuts. Distributors and end users may specify this in their purchase orders by requesting Airfasco MS21042 'Style B' lock-nuts.

Customers may specify low torque MS21042 nuts by specifying LT at the end of the part number:

For more information on the MS21042 'Style B' design please visit


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Dennis Dent

Wm. Dennis Dent

Founder & CEO

Engineering | Chief Pilot
Tim West

Tim West

Director of Corporate Quality