Charlie Kuss wrote:

  At one time, I shared Robin's opinion regarding hardware.  There are

considerable

differences between a commercial grade 8 bolt (stronger, relatively

brittle) and a

common (not high strength) AN bolt. AN bolts are actually softer. They

are designed

to fail "gracefully". This means that rather than cracking or snapping

when over

loaded, they will stretch. A broken grade 5 commercial bolt (a closer

comparison to

the most common AN bolts) and a stretched AN bolt are both junk. The

difference is

that when the commercial hardware fails, it fails catastrophically.

snipped

You ought to try reading FAA AC 41.13-1b  It is very

educational. I've learned a lot from it. As I learn more, I realize that

I knew and

still know a lot less than I thought I did.

  I'm sure that there are areas of each ship where you can safely substitute
commercial hardware for AN hardware. Please be careful that you don't use

commercial

hardware in flight critical areas. I don't want to read about anyone here

in the

NTSB accident reports.
Charlie Kuss
RV-8A fuselage   (better to study on the ground, than be tested in the air)
Boca Raton, Fl.

  I think you meant to say AC 43.13-1b, which I have repeatedly recommended
to all on this list that do not have it ( and2b).   I agree wholeheartedly
with your whole post, altho "soft" may be a bit imprecise in engineering
terms.  I would prefer "ductile",
but your explanation is right on. You want graceful failures and this is what
AN (all now MS) hardware is designed for.

Please take the opportunity to save your life by reading this excellent,
inexpensive
reference work.    snipped
Bill Freeman

Bill,
 You are absolutely correct on both counts. Thank you for correcting me.
Charlie Kuss

 
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