BS A 231:1982

Specifies requirements for the thread runout at the junction of the thread and shank (or thread and head) and at the extreme end of fasteners, the lead thread, for rolled threads used in aerospace construction. Gives a referee method, by optical projection for conformity with these requirements. May be applied to externally rolled threaded products except where special runout or lead thread requirements are specified. Illustrates completely formed thread, full shank fasteners, pitch diameter shank fasteners, external end, taper transition, shoulder transition, shoulder transition, taper transition for oversize shank fasteners, threaded to head fasteners, flush head fasteners threaded to head and comparator chart requirements for determinating length of lead and runout threads.