This standard specifies the characteristics of flat steel washers, cadmium plated, for maximum operating temperature 235 °C, for aerospace applications. They are intended for use primarily underneath nuts, for use underneath bolt heads the compatibility shall be checked.
DS/EN 2138:2000 history
2000DS/EN 2138:2000 Aerospace series - Washers, flat, in steel, cadmium plated
1993DS/EN 2138:1993 Aerospace series. Washers, flat, in steel, cadmium plated