Type: This specification establishes the requirements for self-locking nuts@ wrenching type (i.e.@ hexagon@ double hexagon@ and spline drive)@ made of a corrosion and heat resistant steel of the type identified under the Unified Numbering System as UNS S66286. Classification: a. 220 ksi minimum tensile strength at room temperature b. 850 ??maximum test temperature of parts. Application: Primarily for use in aerospace propulsion systems in temperatures up to approximately 850 ??where nuts are used with bolts capable of developing 220 ksi axial tensile strength at room temperature@ and having UNJ thread form.