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6604 vs 1304 wing attach bolts

jcoloccia

Well Known Member
Okay...some smarty pants out there is gonna know this off the top of their head. I'm doing the inventory on the wing kit, and the hardware list calls out for NAS1304-50 bolts (the long, really thin ones). I ended up with NAS6604-50 bolts, though. Are these parts interchangeable, or did someone at Vans make a boo-boo? I gotta think it's the same part, but Google is frustratingly silent on the issue...
 
John,
At the bottom of the spec sheet for the NAS13XX series bolts is a note to the effect "inactive for new design" or something along that line. Anyway, the NAS66XX sereies replaced the NAS13XX years ago, so what you have is correct.

This is a very familiar question; comes up now and then at work.

Ben R.
RV-9A #90217
Fuselage rear almost done
 
Reviving an old thread, which makes this really weird.

My fuselage kit, circa 2020, was shipped with NAS1304-50. Last week I ordered some more of the same bolts (long story, don't ask). The ones recieved were the NAS6604-50. They look identical sitting side by side. Of course that means nothing for their metallurgy, strength or close tolerance use. Hence my concern.

If the NAS1304 series was discontinued years ago as of 2006 (from the revived thread), how did I get 8 nice looking NAS1304 bolts in late 2020 with my fuselage kit?
 
Make note

If those are the wing attach bolts, make sure that the thread length is correct for your application.

On my RV-10, I noticed that, if assembled per the plans, the nuts would bottom out on the threads before the correct torque was reached. A call to Vans confirmed that the threads on the new bolts were slightly shorter and that it was ok to add another washer to allow proper tightening of the bolt...
 
The NAS1303-NAS1320 specification is one spec covering multiple sizes (diameters) of the same bolt. NAS1304 is for the 1/4" dia bolts. Same with the NAS6603-NAS6620 spec.

The last revision of NAS1303-NAS1320 states, "Inactive for new design after Oct. 30, 1981. See NAS6603 thru 6620."

What this means is that while it's recommended that no new designs specify the NAS13XX, there's nothing wrong with the bolt itself and there are likely still bunches on shelves (but probably none in production anywhere if no one is using them for design). Bolts don't get old sitting on a shelf.

Looking at both specs side by side, there are no huge dimensional or finish differences between the two bolts. Metallurgy is the same, with one additional steel alloy (4140) possible to use for the NAS6604 which wasn't permitted for the NAS1304. Other possible alloys include 4340 and 8740 for both bolts. Heat treat and final tensile properties are identical for both. Both are 100% mag particle inspected at this size.

Bob is correct above - for some diameters, there are slight length changes in the threaded portion. For the 1/4" bolts though, they're the same.

Not advising you, but I'd have no problem using either one interchangeably.
 
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Thanks,
I'll consider my "old" NAS1304 bolts to be like a nice whiskey or a fine wine, that they've only gotten better with age.
 
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