These British Standard apply to the material,dimensions,and finish of washers generally used for facing purposes in aircraft.The washers are primarily for use with B.A.and B.S.F.bolts.
BS SP 10 and 11:1949 history
1949BS SP 10 and 11:1949+A3:2011 Specification for washers for aircraft purposes (primarily for facing purposes)
1949BS SP 10 and 11:1949 Specification for washers for aircraft purposes (primarily for facing purposes)