3a 2nd end thread class 12 1st end thread quantity per inch penetrant inspection per mil-i-6866 anodize inside surface treated un 1st end thread series
Used on aircraft, hercules c-130. 2a 1st end thread class 1st end bulkhead 0.438-20 in., cl 3a, unf; weapon system essential anodize outside surface treated unf 1st end thread series
3a 2nd end thread class 12 1st end thread quantity per inch 1st end bulkhead thd 1.062-12 in., cl 3a, un anodize inside surface treated un 1st end thread series
Used on grumman a10 aircraft. 3a 1st end bulkhead thread class 12 1st end bulkhead thread quantity per inch cadmium surface treated unj 1st end bulkhead thread series