2a thread class right-hand 0.250" thread length fillister head style 0.031" hole diameter 40 thread quantity per inch anodize screw surface treated unc thread series
3a thread class right-hand 0.556" thread length hexagon head style 7.396" grip length 20 thread quantity per inch cadmium surface treated unf thread series
3a thread class right-hand 0.343" thread length hexagon head style 1.438" grip length 24 thread quantity per inch cadmium surface treated unf thread series
Used on w/s: aircraft, intruder a-6e; engine, aircraft tf-30; aircraft, galaxy c-5. flush (flat) countersunk (included angle - less than 135 deg w or w/o chamfer) head style 0.251" grip length 450 single pounds per square inch shear strength
3a thread class right-hand 0.313" thread length flat countersunk head style 48 thread quantity per inch passivate screw surface treated unf thread series