PURPOSE.  This specification establishes the requirements for
procurement of mechanically expanded, self-plugging, blind rivets with a
mechanically-locked-spindle and bulbed blind side.  Blind rivets covered
by this specification are for general purpose use in both thin and thick
sheet applications in aerospace structures and other applications where
only one side of the assembly may be accessible.

CLASSIFICATION.  Rivets covered by this specification shall be of the
following types and compositions:

     TYPE I              Protruding head rivets (NAS1919)
     TYPE II             100 degree Flush head rivets (NAS1921)

     COMPOSITION B       Aluminum alloy (5056)
     COMPOSITION C       Corrosion resistant steel (A286)
     COMPOSITION M       Monel (Nickel-copper alloy)

CLASSIFICATION REQUIREMENT IDENTIFIER.  The requirements defined in this
specification shall be identified by the requirement identifying numbers
derived as shown below:

          NAS1900-1B
          _______ __
             |    ||          B=COMPOSITION B
             |    ||__________C=COMPOSITION C
             |    |           M=COMPOSITION M
             |    |
             |    |______|1=TYPE I
             |           |2=TYPE 2
             |
             |______DOCUMENT NUMBER