3a thread class right-hand 0.500" thread length flat chamfer head style 28 thread quantity per inch screw cap, socket head, self locking screw to be self locking; this locking element must be a non metallic patch in accordance with mil-f-18240 except that prevailing zinc surface treated unc thread series
Used on kc-135 acft. 3a thread class right-hand 0.370" thread length dished hexagon head style 2.058" grip length 28 thread quantity per inch hex head bolt aluminum surface treated unjf thread series