Whats the difference btwn National Aerospace Standards(NAS) and Military Standards(MS) aviation fasteners ?

Question

which one is the best?

Answer 1

I worked in the aircraft industry for the best part of 28 years, so these designations have a great significance.

Essentially, there is very little difference between the 2. For instance, you could take a s***w like an NAS603-10 (the '3' denotes 3/16ths inch diameter, while the -10 denotes the length in 32nds of an inch) which has a particular material specification, but the military standards, will give the same s***w a totally different designation. There are also variants such as adding a 'P' which tells you that the s***w has been cadmium plated.

The Boeing Corporation has it's own numbering system which usually begins with the letters 'BAC' plus 'S' for s***w, 'R' for rivet, and 'N' for nut and although most of their fasteners were usually quite common fasteners, they would never confirm any equivalency.

In the case of rivets, you would find various identifying marks on the head which would indicate the material spec in terms of hardness, and again, Boeing had it's own version, as do Airbus, although Airbus generally used the NAS and MS part numbers for common fasteners.

Most experienced aircraft engineers would look up the part they need in the Illustrated Parts Catalogue (IPC) which may give all the possible alternatives to the part they would normally use.

Basically, NAS is for civil aircraft and MS is for the military, although, as above, there is a lot of 'commonality'

  

Answer 2

Like zitless said, there is a lot of commonality.

I see both types of fasteners called out in the C130 structure drawings, and these are drawings done over 40 years ago. Just depends on the requirements, but I'd have to say that neither one is actually better.