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Bolt Torque Specs
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rdewees(at)mindspring.com
Guest

Posted: Wed Jun 14, 2006 3:40 am Post subject: Bolt Torque Specs

I don't get this guy's math to work out.  Is he talking about inch pounds?

Ron

Noel Loveys wrote:



[quote] I only use the drag of the fibre lock nut (AKA friction torque) when 

 it is specified.  Wearing of the fibres in the locknuts is the main 

 reason I dump them after they have been tightened three times.  In the 

 overall scheme of things they are cheap enough to use relatively new.

  

 As for the torque wrench I tend to check mine out with a known weight 

 every couple of months.  Right now for 200"Lb. I set for 187"LB.  

 checking it is easy as suspending a known weight on the handle at a 

 specific distance from the centre of the stud and then adjusting the 

 wrench to just click at that torque.

 e.g. 16.6Lb. suspended at 12" from the centre of the stud = 200"Lb.  

 When calibrated this way the torque wrench should be less than 1% 

 out.  you can also put the same weight at 6" top check the calibration 

 of 100"Lb.

  

 In Canada torque wrenches used on certified A/C have to have a 

 certificate of calibration in effect before the wrench is used.

  

  



 Noel



     --

moorecomp(at)yahoo.com
Guest

Posted: Wed Jun 14, 2006 4:59 am Post subject: Bolt Torque Specs

Norman,



As this post has been replied to many times, I guess

the original post has been lost, he was asking about

the 6 bolts in the center section of the spar. Copy of

the original post below.



 	  Quote: 	
		  Subject:      Bolt Torque Specs 

From:      Randy Bryant (randy(at)shadycreekoutlaws.com)


	


 	  Quote: 	
		  Date:      Mon Jun 12 - 7:11 AM 


	


 	  Quote: 	
		  I am finishing up the center spar for my 601 XL.

There are 6, AN4-15A bolts that go through the center

spar.  Are there torque specifications on these bolts

that I need to follow?


	


 	  Quote: 	
		  Thanks in advance,


	


 	  Quote: 	
		  Randy

XL Wings - Plans Only

http://www.n344rb.com


	


Best regards,



Craig Moore A&P

701 builder wannabe

--- "normskiroo(at)ukonl" <normskiroo(at)ukonline.co.uk>

wrote:



 	  Quote: 	
		   

 "normskiroo(at)ukonl" <normskiroo(at)ukonline.co.uk>

 

 Randy,

 

 A word of caution here, I have this morning checked

 my CZAW drawings and they specify the bolts that

 attach the wings on my XL are AN5 15A not AN4 15A.

 The torque for these bolts according to the data

 CZAW gave me is - 

 100 to 140 in. lb. recommended 11.3 to 15.8 Nm with

 a limit of 25.4 Nm.

 

 I shall, next time a am down at the aircraft use a

 vernier gauge to confirm the size.

 During a wings off/back on operation some time ago I

 managed to strip the threads of one of the bolts

 /nuts by over tightening and I was only using a

 ratchet socket handle six inches long!

 Needless to say the drilling of the bolt head took a

 while to get the whole thing out!

 

 Regards,

 Norman 601 XL G-DONT 40 hours, UK


	


__________________________________________________

noelloveys(at)yahoo.ca
Guest

Posted: Wed Jun 14, 2006 7:44 am Post subject: Bolt Torque Specs

Yes...  symbol for inches is/was " and Ft. '



There fore  "Lb. = Inch pounds & 'Lb. = Ft. Lb.



Noel



[quote] --

JERICKSON03E(at)aol.com
Guest

Posted: Wed Jun 14, 2006 8:40 am Post subject: Bolt Torque Specs

In a message dated 6/13/2006 10:44:46 PM Central Daylight Time, randy(at)shadycreekoutlaws.com writes:

  	  Quote: 	
		   thought that the reason for torquing bolts was to achieve the proper 'stretch' in the bolt...  I know in an engine, you torque rod bolts, they stretch and apply tension to the rod caps and this helps hold the cap on...  If you over torque, you 'stretch' the bolt past its elasticity and loose this extra holding capacity...

  

 Maybe I'm wrong...??  I just hate having to tighten something as far as it will go then 1/4 turn more as the torque specs...

  

	


  

 The application of the bolt has to be considered. The AN/MS bolts, be they size 4 OR size 5, and it would be good to know this up front to get the torque correctly applied, are in a static, clamping design. ZAC reference to AC 43.13 is good advice.

  

 The design of the rod cap bolts, mentioned above, has two functions. Clamping the cap to the rod, and then withstanding the dynamic loads of the weight of the piston & rod as it changes direction at top dead center due to crankshaft rotation. High RPM results in very high tension loads being imposed on the bolt's. Rod cap bolts are not just ordinary bolts, they are stronger to withstand the high RPM created dynamic loads imposed. They are usually replaced rather than being reused. 

  

 Some high rpm engines have the rod and rod caps clocked around to reposition the bolts so they are not in a straight line with the rod, thus relieving some of the dynamic stress on the bolt.

  

 Some years ago one helicopter design would stretch the rod bolts as the result of engine over speed events. The bolts would then fail in tension.

  

 Point is, don't confuse bolt's, rod cap, AN, MS, Grade 8, grade what ever, METRIC,,,,.

 Use the correct torque for the bolt spec and size being addressed please.

  

 Check the plans to be sure of the bolt size, then apply the correct torque for that bolt size. Sorry to be confused, is it size 4 or size 5 that should be considered here?

randy(at)shadycreekoutlaw
Guest

Posted: Wed Jun 14, 2006 9:29 am Post subject: Bolt Torque Specs

So basically, the size of the bolt (AN4, AN5..etc.) is all that should be  considered in regards to bolt torque...?  What application the bolt is  being used for doesn't play a part..?

  

 I'm not being argumentative on this subject, I just want to be for sure how  many inch pounds or foot pounds I should torque these particular AN4-15A bolts,  being used in the center spar on a 601XL... There are 6 of them...  If the  correct torque is 70 inch pounds, that's fine by me.. I just want to know for  sure that is the correct value and what I should be torquing to...

  

 This is my first airplane build, so I'm not well versed in a lot of areas  about plane building, and I just thought it was strange that the plans  didn't specify the amount of torque for particular bolts...  Maybe this is  completely normal...probably is...

  

 I was just expected a straight answer from ZAC when I asked  specifically what was the torque value for the 6 bolts, called for in their  plans, to bolt the center spar together...  I expected an answer such as:  "70 inch pounds"..."100 inch pounds"..etc.  Had I asked a broad question  such as: "What is the general torque value for an AN4 bolt", I would expected  the answer I got...Go look in the "Acceptable Methods Techniques, and Practices"  book...  But when I asked about a specific bolt, used in a specific  application, specified by their plans, I expected a more specific  answer...

  

 Again, this is my first airplane project and maybe this was the correct  answer, I was just expecting something a little more specific...

  

 Thanks again,

  

 Randy

 Do Not Archive

  

 [quote]   ---

noelloveys(at)yahoo.ca
Guest

Posted: Wed Jun 14, 2006 12:23 pm Post subject: Bolt Torque Specs

Randy:  

  

 The size of the bolt is the prime  consideration to use when determining the torque to put on a nut or bolt.   However the application can also be taken into consideration.  In those  instances the MMM ( Manufacturers Maintenance Manual) will give you a specific  torque to use.  The MM will also specify if you should take into account  the extra friction on locknuts (Friction torque) or not.  for all the rest  of the applications you are safe to use the torques in AC43.  Remember to  make sure no less than 1.5 threads (Puts the nut into safety)and no more than 3  threads (stops the nut from shouldering out on the bolt) show through a lock  nut.  All this and much, much more  is covered in  AC43. 

  

 For most things you can use the data in AC43  but be careful that there isn't conflicting data in the ZAC manuals.  In  that case always follow the manual.

  

  

 

Noel [quote]   

   --

p.mulwitz(at)worldnet.att
Guest

Posted: Wed Jun 14, 2006 2:05 pm Post subject: Bolt Torque Specs

I think this issue is getting way overblown.  My personal guess is it 

doesn't really matter how much torque is applied to these particular 

bolts.  If you just turn the wrench until the nuts seem tight then it 

will probably be OK.



My reasoning is a result of my analysis of the actual function of 

these bolts.  It seems to me the primary function of the bolts is to 

prevent the wing spars from moving with respect to the center 

pass-thru structure.  In this application the really important 

quality is the shear strength of the bolts rather than how tightly 

they are attached.  The real load is completely in the shear 

direction.  The only purpose of the nut is to keep the bolt in place 

so the strength of the bolt shaft can do its job.



This application is quite different from the bolts that hold a 

cylinder head in place on an engine.  In the cylinder head case it is 

important that the bolts are properly torqued so the force holding 

the head in place is evenly distributed.  This prevents warping of the head.



I admit I am not really a qualified mechanical or aeronautical 

engineer.  This is just my best guess.  It is also consistent with 

ZAC folks basically saying they don't really know or care how much 

torque is used for this application.



Paul

XL wings

do not archive



 	  Quote: 	
		  I'm not being argumentative on this subject, I just want to be for 

sure how many inch pounds or foot pounds I should torque these 

particular AN4-15A bolts, being used in the center spar on a 

601XL... There are 6 of them...  If the correct torque is 70 inch 

pounds, that's fine by me.. I just want to know for sure that is the 

correct value and what I should be torquing to...

noelloveys(at)yahoo.ca
Guest

Posted: Wed Jun 14, 2006 3:19 pm Post subject: Bolt Torque Specs

You are right Paul the loads on these bolts are shear and not tensile.  The

application could probably be better suited to AN5 - 15 bolts with

castellated nuts and cotter pins.  But if ZAC specifies the -15a bolts with

fibre locknuts they must have a reason.  That reason may not be outwardly

apparent.



I put an Ivo on a plane and noticed that the heads of the mounting bolts

were not drilled for lock wiring...  Thinking this was a mistake I phoned

the factory to check it out.  What I was told was they intentionally didn't

used drilled heads because they wanted the owners of their props to spend

time inspecting the blade roots and checking the torque on the prop blots at

regular intervals.  They said people don't like to cut lock wire because

they have problems getting it back properly



Noel



[quote] --

JERICKSON03E(at)aol.com
Guest

Posted: Wed Jun 14, 2006 3:49 pm Post subject: Bolt Torque Specs

In a message dated 6/14/2006 12:30:51 PM Central Daylight Time, randy(at)shadycreekoutlaws.com writes:

  	  Quote: 	
		   So basically, the size of the bolt (AN4, AN5..etc.) is all that should be considered in regards to bolt torque...?  What application the bolt is being used for doesn't play a part..?

  

	


  

 Randy, Both are considered by the designer.

  

 As for us,, There is much to learn in this great hobby of ours, amateur built aircraft. Hardware is a significant part of the learning. What fasteners are and how they are used in the design is not the least of it. 

  

 As others have said, the plans and builders hand books lay it out, mostly. The designer has done the work for us, you did well to ask ZAC. Not liking their answer is another thing.

  

 Finding a good EAA chapter, and a Technical Counselor for help is a good start for a new project. Lot's of help available through the EAA Aviation Safety Program. nuf said.

  

 Looking at a Standard Aviation Maintenance Handbook, Jeppesen, and the FAA AC's, 43.13 & others, you will find that the bolt and the nut called for, determine the torque for a particular installation, and the use, sheer or tension, as well as size all are factors. So it is useful to study up, and understand the designers plans and specs. builder hand books.

  

 Do not buy the thought that it does not really matter what the torque is. We are very lucky to have the experience of others in aviation there for our benefit now. 

  

 Specifically, It is concerning that at least two other builders on the list have commented that their plans call for size 5 bolts, while you continue to mention size 4 bolts? So I wonder if all three 601 builders are looking at the plans correctly?

  

 Can you please look again to verify the size bolts in the wing you have been wondering about. 

  

 Jerry

601zv(at)ritternet.com
Guest

Posted: Wed Jun 14, 2006 4:21 pm Post subject: Bolt Torque Specs

Seems to me there was some confusion over which bolts. the six center  bolts, as I think were originally inquired about, are AN4, while the 12 wing  attachment bolts are AN5, no?

 [quote]   ---

larry(at)macsmachine.com
Guest

Posted: Wed Jun 14, 2006 4:58 pm Post subject: Bolt Torque Specs

Randy,

The best option is to use the best rated torque allowable specified for 

¼-inch bolt, 125K material and fine threads.  Torque should be not less 

than 100-inch-pounds for a bolt of this size.  The designer sized the 

bolt for shear loads involved and the torque required insures best grip 

between material surfaces that keep the spars and plates from slipping 

on one another.   One cannot assume that bolt holes will remain sized 

well enough to take care of it in shear alone.  The materials are way 

too thin for that long term.  Steel buildings are torqued religiously 

for the same reasons.  The material grip between beams is as important 

as the tension and shear of the bolt.  Your spars are not the place to 

become complacent about this question.  Example: Warp Drive specifies 

120 inch pounds for the same size 125K bolt to secure their aluminum 

prop sandwich.  100 inch pounds would be a good place to start.

Respectfully,

Larry McFarland

Paul Mulwitz wrote:

 	  Quote: 	

 <p.mulwitz(at)worldnet.att.net>

 I think this issue is getting way overblown.  My personal guess is it 

 doesn't really matter how much torque is applied to these particular 

 bolts.  If you just turn the wrench until the nuts seem tight then it 

 will probably be OK.

 I admit I am not really a qualified mechanical or aeronautical 

 engineer.  This is just my best guess.  It is also consistent with ZAC 

 folks basically saying they don't really know or care how much torque 

 is used for this application.

 Paul

 XL wings

 do not archive

> I'm not being argumentative on this subject, I just want to be for 

> sure how many inch pounds or foot pounds I should torque these 

> particular AN4-15A bolts, being used in the center spar on a 601XL... 

> There are 6 of them...  If the correct torque is 70 inch pounds, 

> that's fine by me.. I just want to know for sure that is the correct 

> value and what I should be torquing to...

>

randy(at)shadycreekoutlaw
Guest

Posted: Wed Jun 14, 2006 5:11 pm Post subject: Bolt Torque Specs

You are right...  kinda... I know which bolts, the center spar takes  the AN4-15A, six of them, and the 12 wing attachment bolts take AN5-15A...   I was just curious, that in this particular application, the center spar AND the  wing attachment bolts, how many inch pounds, foot pounds...etc., ever what  denomination you want to give, are the particular bolts torqued to?

  

 Thanks,

  

 Randy

 Do Not Archive

  

 [quote]   ---

randy(at)shadycreekoutlaw
Guest

Posted: Wed Jun 14, 2006 5:14 pm Post subject: Bolt Torque Specs

Thanks!



The answers are getting better and more easy for me to understand...



Basically the way I'm understanding it now, is that if the load on a 

particular bolt being used is shear, as long as the "bolt stays through the 

hole" it's Ok...



When it comes to a bolt loaded and relying on it's tensile strength, torque 

is a more important factor...



Correct??



Thanks much,



Randy



Do Not Archive

---

randy(at)shadycreekoutlaw
Guest

Posted: Wed Jun 14, 2006 5:22 pm Post subject: Bolt Torque Specs

Thanks Larry,



Yet another good answer... We may get to the to bottom of this after all! 





I agree, about the spars being an important part, if I didn't think so, I 

would have never brought this up...



Thanks again,



Randy



Do Not Archive

---

p.mulwitz(at)worldnet.att
Guest

Posted: Wed Jun 14, 2006 5:25 pm Post subject: Bolt Torque Specs

 	  Quote: 	
		  

 Seems to me there was some confusion over which bolts. the six center bolts, as I think were originally inquired about, are AN4, while the 12 wing attachment bolts are AN5, no?

   ----- 

 	
 



 I suspect the choice of bolts (along with many other things) has changed over the years.  My plans dated mostly 05 use AN5 bolts.  Perhaps the older plans call for AN4 bolts.



 Paul

 XL wings

 do not archive

randy(at)shadycreekoutlaw
Guest

Posted: Wed Jun 14, 2006 5:27 pm Post subject: Bolt Torque Specs

Sounds good to me...  This is my first aircraft project and I really didn't 

know if torque of these particular bolts were 'critical'...  That's why I 

thought I'd ask if anyone could give me a definate number, if there was 

one...  If there is not, I'm Ok with that... If the correct answer is, just 

tighten them "good en' tight" so they won't fall off, I can understand 

that...



Sorry if I opened up a can of worms here, that was not my intention...



Thanks again,



Randy



Do Not Archive

---

randy(at)shadycreekoutlaw
Guest

Posted: Wed Jun 14, 2006 6:06 pm Post subject: Bolt Torque Specs

My plans are 10/04 and they call for AN4 bolts in  the center spar, and AN5's for the wing attachment...

  

 Randy

  

 Do Not Archive

  

 [quote]   ---

601zv(at)ritternet.com
Guest

Posted: Wed Jun 14, 2006 6:19 pm Post subject: Bolt Torque Specs

Yes, my 04/04 plans call out AN4's.

 [quote]   ---

JAPhillipsGA(at)aol.com
Guest

Posted: Wed Jun 14, 2006 8:11 pm Post subject: Bolt Torque Specs

Randy, you probably need to find out the torque for the two rear spar bolts as well, don't you ?  Say, aren't they a different size ? I can't say what's in the mind of ZAC, but I know you can't get a tordue wrench on but a few of these nuts anyway so I torqued what I could and tightened the rest about the same ? Wings still on ! Best of Luck, Bill of Georgia

leogates(at)allvantage.co
Guest

Posted: Thu Jun 15, 2006 10:03 am Post subject: Bolt Torque Specs

Do not try this with an AN3 Bolt, it will break - Guaranteed!



Don't as how I know.



Do not archive.



Leo Gates

N601Z

Randy Bryant wrote:



 	  Quote: 	
		   Thanks Frank,

  



 I guess I'll just tighten em' as tight as they'll go, then go about 

 1/4 turn more... that should do it..

  

 Thanks,

  

 Randy

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