However, a very common confusion exists in the aerospace fastener community. Many people mistakenly associate all "NAS03xx" series with bolts or screws. While NAS0300 through NAS0320 generally cover shear bolts and tension bolts, NAS0331 often cross-references protective devices. When searching for "nas0331 pdf," you are likely looking for one of two things:
The PDF details the heat treatment and plating (Cadmium, Zinc-Nickel, or Passivated). nas0331 pdf