scope:

This standard specifies requirements for closed corner, counterbored, fixed, reduced series anchor nuts, with a self-locking feature achieved by forming the upper portion out-of-round.
These nuts are intended for use in aircraft assemblies, in which the fasteners are mainly objected to shear loads. The counterbore is deep enough to accommodate a bolt shank in excess of assembly thickness, as well as the incomplete threads.
They are intended to be used with threaded parts of 1 100 MPa ) tensile strength classification.
The cadmium plating restricts the application to temperature not exceeding 235 °C.