Specification for screws, pan and 100° countersunk head, hexalobular drive recess (unified threads below ¼ inch) in various materials|Acceptance inspection, Threaded fasteners, Tensile testing, Bolts, Aluminium alloys, Fasteners, External-thread fasteners, Macroscopic examination, Quality assurance, Steels, Forgings, Aircraft components, Heat treatment, Hexagonal-head fasteners, Threads, Pan-head fasteners, Dimensional tolerances, Internal-thread fasteners, Metallography, Space technology components, Statistical quality control, Surface defects, Unified screw threads, Marking, Hardness, Air transport engineering, Threaded components, Inspection, Defects, Nuts