AIRCRAFT QUALITY BOLTS

Hi again- Apparently there is no standard 'Grade' for Aircraft hardware such as bolts and nuts, only Aircraft 'Quality'. Does anyone know of any 'Standards'
for this 'Quality'? The best that I can determine is that each manufacture of Aircraft Quality Hardware have their own standards and are not made to any 'Industry' standards. I have found out that some manufactures will not even give a PSI rating for their nuts and bolts, only stating that they are of 'Aircraft Quality'. Can anyone put more light on this? Thanks,
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On 2/4/14, 8:18 AM, Bob Lowe wrote:

There are strict standards... You see that 'aircraft quality' BS statement thrown around all the time by marketers.
Only have a few seconds right now, but Google 'AN hardware' for a start. Note that the vast majority of aircraft threaded fasteners are fine thread.
There are many special fasteners used in aircraft as well.
Erik
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On 2/4/2014 10:18 AM, Bob Lowe wrote:

Fasteners will be spec'ed by the manufacturer for the purpose as far as tensile strength, etc., using a specific set of spec's whether they be military or internal for civilian aircraft. The "Quality" refers to the QC pedigree that they meet the standard pedigree and have the paperwork associated for whatever performance spec is pertinent; it doesn't mean anything specific regarding what that performance spec to which it adheres is; that's referred to but not the same thing.
It's like the "N-Stamp" for nuclear-qualified pieces-parts for reactors; the actual spec's met are different depending on what the reqm't is, the N-Stamp only assures that it was produced according to the protocol of documentation and certification and record-keeping required which is far beyond that of "ordinary" material which may, actually, be of precisely the same actual functional spec.
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message

hardware

any

and

"national aerospace standard" or for short, "nas"
https://www.google.com/#q=nas%2Bmil%2Bspec%2Bfasteners
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On 2/4/2014 11:18 AM, Bob Lowe wrote:

If you ever need the absolute best! I've used these in a few circumstances that nothing else would work.
http://unbrako.com/
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Are these things made in India?
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On 2/4/2014 6:50 PM, Cydrome Leader wrote:

Looks like it but they are expanding in Europe. (They still make the best. Not cheap, but the best!)
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On 2/4/2014 10:18 AM, Bob Lowe wrote:

For the most part, AN series bolts correspond to grade 5
BUT
every nut and bolt has been x-rayed for internal flaws.
<http://www.sportair.com/articles/1Aircraft%20Hardware%20-%20What%20You%20Need%20To%20Know.html <http://www.faa.gov/aircraft/safety/programs/sups/standard_parts/media/standard_parts.pdf Congress enacted theFastener Quality Act (FQA) (15 U.S.C. 5401). Enacted in 1990, the FQA has been subsequently amended several times. However, the basic intent remains the same, i.e., to ensure the qual ity of fasteners and to prevent mismarked, misrepresented, and counterfeit fasteners from entering the commercial market.
And
CONSIDERATIONS. When purchasing and installing standard parts, consider the following: ? A Certificate of Conformity (C of C) should be provided by the producer of a standard part. ? A standard part should carry a mark indicating the part has been produced in accordance with the specification requirements. ? A part is no longer considered?standard? if it is used in a critical application that imposes qualification or quality control requirements beyond the standard specification. ? To facilitate traceability, commingling like fasteners from different lots is not recommended. ? Section 21.303(b)(4) provides that acceptable government specifications are limited to those published by the U.S. Government. Parts produced to a foreign standard may, however, be acceptable for in stallation on foreign type-certificated aircraft and products. ? Installation of a standard part must bein accordance with the requirements of part 43. Generally, a standard part may be replaced with an identical standard part; however, substituting standard parts would require a demonstration of acceptability in accordance with part 43.
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On Tue, 04 Feb 2014 16:18:04 +0000, Bob Lowe

Yes there are standards. I seem to remember a reference to "AN" fastenings - the AN said to mean Army-Navy.
Do a bit more research. Perhaps check the McMasters or Aircraft Spruce site.
--
Cheers,

John B.
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replying to Bob Lowe, Bob Lowe wrote:

as
of
Thanks - Oh yes, there can pages and pages of specs, but now I am finding out why I was never able to see or obtain any of these specs. I would have to buy a book or two to see these specs. I doubt if anyone is going to just print too much information on this for free reading on the web. Of course I'll keep looking but I don't have much hope for this. They will sell me an MS 39 bolt but it is up to me to know what this is. I guess there is no Grade Number per se` for an aircraft bolt - just 101 specs. Thanks again.
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Bob Lowe wrote:

If they are labeling the bolts "aircraft quality" they are probably not. Every bolt used in aircraft should have a spec. on it. There are titanium bolts, SS bolts, huck bolts and every other type of fastener and they all have a spec. on them. I believe that a lot of information is listed in FAR 43:13 as to bolt specs.
John
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On 2/4/14, 7:50 PM, John wrote:

Yes, check it out... go here and download a (free!) copy of AC 43.13-1B, it's about 3/4 of the way down the page.
http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.list/parentTopicID/114
The full PDF is about 16.75 MB, but you'll have the option to download it by individual chapter if you wish.
AC is FAA speak for 'Advisory Circular', they have thousands of them... 43 means it pertains to part 43 of the Federal Aviation Regulations (FAR's) concerning Maintenance, Preventative Maintenance, Rebuilding and Alterations. The rest is just the rest.
This is an interesting document, lots of very good information!
The section covering bolts proper begins at 7-34.
The FAA offers loads of other advisory circulars, handbooks and other training materials, all free just for the download. I suggest one and all take a look.
Erik
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replying to Bob Lowe, Bob Lowe wrote:

as
of
Hi guys - I am making progress, thanks...found a wealth of info on the AC43.B-1B concerning identification of the hardware and some torque and dimension specs but didn't find much on the actual specs other than that, but I sure haven't read it all. I did come across what may be called a basic AN Bolt Designator that may be interesting and necessary as a first step, at: Challengers 101.com/ANBolts. I did find a good site for some actual manufacturing specs on AN Bolts but then lost it and couldn't find it again. And I did find a whole lot a places that would like one to buy this information. I am finding it hard to get into any of the Gov specific information. I will persevere, and thanks again for everything.
Bob Lowe
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On 2/5/2014 11:18 AM, Bob Lowe wrote:

Bob, the real question here is - what are you trying to do?
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replying to Bob Lowe, Bob Lowe wrote:

as
of
Hi - Richard, You asked what am I trying to do. Well this can be a multi fold answer. First of all, I am trying to learn. I use to own an airplane and I would just buy a bolt without really know what I was buying. I didn't take the time to determine what may be better - I just took other peoples word for it as this is not too uncommon, right. For the last few years I have been drawing hundreds of pictures of a different Gyrocotors and I thought maybe, just maybe, I could find time to build a simple one. I use to look at the four fire-wall engine mounting bolts of my plane and think, if I were doing this I sure would have used heavier looking bolts. And as you may surmise, I should surely understand the strength of a bolt to get anywhere with this. Even if I should buy a 'kit' I know that I would be tempted to use a better bolt. And I thought that I had better learn all I can on just what a better bolt may be. And then I am always making things out of surplus Mil-spec bolts as stock, mostly of stainless on my lathe, and again, it would be better to learn more about what I may be using. I am retired now and I find myself trying to learn the things that I didn't have the time to do before. That about covers 'what I am trying to do' Richard...thanks for your curiosity.
Bob Lowe
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in message

You can make a quick guesstimate of tensile strength from 100,000 PSI times the area of the thread root or the tap drill. Shear strength is about half of that, for the shank or thread root, whichever applies. For better numbers: http://www.ti64.com/v/vspfiles/assets/docs/fasteners%20101.pdf Ksi = KiloPSI.
jsw
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On 2/6/2014 10:18 AM, Bob Lowe wrote:
I use to look at the four fire-wall engine mounting bolts of

Hi Bob,
Look, I have to say something that could be taken negatively, but I have to say it. So, in the interest of safety and education consider this...
Bad idea.
Until you can calculate the loads imposed on a fastener, _don't_ make it stronger. In fact, don't make any changes at all.
Two reasons off the top of my head...
One: consider the structure that the bolt penetrates. A Larger bolt means a larger hole too. Sometimes that will be ok - but sometimes the edge margin could be critical and enlarging the boat could weaker the attach point. In trying to make the structure stronger you could easily make it weaker!
Two: sometimes structures are designed to fail in a particular manner. Making a connection stronger in the wrong place could defeat that strategy and cause a much worse failure to occur.
And three: A proven design doesn't need to be stronger. If anything it needs to be lighter!
Just looking at a detail (like a 747 engine mount?) one often wonders how the engine can possibly stay on the wing. But it does, quite well.
It's all in the numbers.
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wrote:

And using a grade 8 ot L99 bolt in place of the specified AN bolt MAY also cause a failure. Better bolt? By spec, perhaps. In use? Perhaps not. A grade 8 bolt MAY fail from vibration fatigue where the "inferior spec" AN would not harden and crack.
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On 2/7/2014 6:34 AM, snipped-for-privacy@snyder.on.ca wrote:

Excellent point!
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wrote:

Re engine mount bolts. I once had the job of removing the forward engine mount bolt on an engine on an Air force Boeing 707. The A.F. was trying some sort of iffy maneuver and the thing stopped flying about 50 ft above the runway. After the Crash Truck had inspected things and they taxied in the first inspection showed no ill effects and everyone was quite impressed. The next morning one of the maintenance troops commented that the cowling didn't seem to fit quite right and after uncowling the engine and dragging up stands and much peeping and peering it was discovered that the engine mount bolts were bent and the engine was slightly out of line.
Apparently the Boeing engine mount designers DO know what they are doing :-)
The final decision, by the Depot, was to remove the engine and then gauge the engine mount brackets in the pylon, measure bolt holes for elongation and do die checks of everything, which was where I came in as the front bolt was bent too badly to simply drive out so the Machine Shop was called for a solution.
After we got the bolt out without any damage to the supporting structure they fiddled around for some time measuring, checking, looking and reporting everything back to Boeing and finally about a month later they hung a new engine and test flew it.
--
Cheers,

John B.
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