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nuts n bolts

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Paul Petty

Joined: 11 Jan 2006
Posts: 226
Location: Mississippi

Posted: Fri Jan 13, 2006 6:40 am Post subject: nuts n bolts

Fellow Kolbers,



I am installing the AN hardware in Ms. Dixie for pre final assembly to make sure everything fits and works before taking apart for final paint and covering. Here is my question.. Drilled AN bolts vs non drilled AN bolts and nylon lock nuts... My plans call for drilled AN bolts in some areas and non drilled with nylon nuts in others   Personaly I like the nylon lock nuts vs the drilled with cotter pins. One reason is climbing in and out of the airplane the cotter pins will get caught on clothing and human flesh  . Problem... One area I want to use a non drilled AN bolt with a nylon nut is the control stick bolt. AN-4-7 (I think) is to short to get the required 3 threads extruding and the next 2 sizes will bottom out before snugging up the connection. Can any of the experts see a problem with adding a few more threads (via die set) to the AN 4 bolt? In addition, why would an aircraft designer choose one type fastener over the other?

_________________
Paul Petty
Kolbra #12
Ms Dixie
912 UL 70" warp

Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Fri Jan 13, 2006 7:15 am Post subject: nuts n bolts

Rather than try and cut threads into the bolt, use a thinner AN nut.

And if necessary, thin washers to shim everything perfect.

Check out the AN-364 on this page:

http://www.aircraftspruce.com/catalog/hapages/an363.php

Keeping several extra AN-364 nuts available in AN-3 and AN-4

sizes is handy for situations such as you describe.



Richard Pike

MKIII N420P (420ldPoops)



Paul Petty wrote:



 	  Quote: 	
		  



Fellow Kolbers,

<snip> Problem... One area I want to use a non drilled AN bolt with a nylon nut is the control stick bolt. AN-4-7 (I think) is to short to get the required 3 threads extruding and the next 2 sizes will bottom out before snugging up the connection. Can any of the experts see a problem with adding a few more threads (via die set) to the AN 4 bolt? In addition, why would an aircraft designer choose one type fastener over the other?



--------

Paul Petty

Kolbra #12

Ms Dixie





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=3621#3621

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

ceengland(at)bellsouth.ne
Guest

Posted: Fri Jan 13, 2006 7:34 am Post subject: nuts n bolts

Paul Petty wrote:



 	  Quote: 	
		  



Fellow Kolbers,



I am installing the AN hardware in Ms. Dixie for pre final assembly to make sure everything fits and works before taking apart for final paint and covering. Here is my question.. Drilled AN bolts vs non drilled AN bolts and nylon lock nuts... My plans call for drilled AN bolts in some areas and non drilled with nylon nuts in others [Question]  Personaly I like the nylon lock nuts vs the drilled with cotter pins. One reason is climbing in and out of the airplane the cotter pins will get caught on clothing and human flesh [Shocked] . Problem... One area I want to use a non drilled AN bolt with a nylon nut is the control stick bolt. AN-4-7 (I think) is to short to get the required 3 threads extruding and the next 2 sizes will bottom out before snugging up the connection. Can any of the experts see a problem with adding a few more threads (via die set) to the AN 4 bolt? In addition, why would an aircraft designer choose one type fastener over the other?



--------

Paul Petty

Kolbra #12

Ms Dixie




	


In the certified world, the selection process goes something like:



Nyloc is ok unless the joint itself is designed to rotate; then you need 

cotter keys. The exception to nylocs is in extreme temperature 

environments, like things attached to an engine where the heat would 

weaken the nylon. There are all-metal friction locking nuts for that 

application.



Take a look at your inlaw's RV-8. Even the aileron bellcranks use 

nylocs, because there's a brass bushing that the rod end moves on & the 

bushing is locked down by the bolt/nut in the weldment. However, the 

rudder pedals probably pivot on the bolts themselves (if they are built 

like my RV-4) & a cotter key is required. Logic is that a rotating bolt 

might overcome the locking force of the nyloc & unscrew the bolt.



Cutting threads will weaken the bolt (original threads are 'rolled', not 

cut), but the clamping force required for a control stick isn't likely 

to stress the bolt at all. The much simpler solution, if you have room, 

is to just add a couple of flat washers under the nut. AN specs allow up 

to (I think) 3 or 4 washers under the nut, & you can add a couple under 

the head, also. The logic is to allow for just the problem you are 

encountering, without having to recut threads.



Charlie

WillUribe(at)aol.com
Guest

Posted: Fri Jan 13, 2006 7:37 am Post subject: nuts n bolts

Hi Paul,

My A&P friend made me change the nylon lock nuts on the control  stick to 

castellated nuts with drilled bolts before the DAR inspected my  FireStar because 

they were moving joints and the nylon lock nuts may  work themselves out.  He 

said the DAR would not pass  it using the nylon lock nuts because it is 

common practice to use  castellated nuts on moving joints.

 

Hope this helps,

Regards,

Will Uribe

El Paso, TX

FireStar II    N4GU

C-172  N2506U

Restoring a PA-22-108  N4551Z

http://home.elp.rr.com/airplane 

Do  Not Archive

 

P.S. See you in March

 

 

 

--

neilsenrmf(at)comcast.net
Guest

Posted: Fri Jan 13, 2006 7:37 am Post subject: nuts n bolts

Paul



When I had my plane inspected by the local EAA inspector he stated that 

nylock nuts were not to be used on any attachment that rotates. Dennis 

Souder's comments were people some times forget to install the cotter pins 

so he liked nylock. The FAA's inspector said he didn't care (he was a jerk 

that only cared that the paper work was ok). As for cutting additional 

threads, I did this a few times but is it OK?



Rick Neilsen

Redrive VW powered MKIIIc



---

Paul Petty

Joined: 11 Jan 2006
Posts: 226
Location: Mississippi

Posted: Fri Jan 13, 2006 8:20 am Post subject: Re: nuts n bolts

Thanks guys,



So if it moves, cotter pin it. If it dont Nyloc it. cool!

_________________
Paul Petty
Kolbra #12
Ms Dixie
912 UL 70" warp

Steve Boetto

Joined: 11 Jan 2006
Posts: 364

Posted: Fri Jan 13, 2006 8:39 am Post subject: nuts n bolts

In a message dated 1/13/06 9:04:12 AM Central Standard Time, lynnp(at)g-gate.net 

writes:



 	  Quote: 	
		   Drilled AN bolts vs non drilled AN bolts and nylon lock nuts... My plans 

 call for drilled AN bolts in some areas and non drilled with nylon nuts in 

 others [Question]  Personaly I like the nylon lock nuts vs the drilled with 

 cotter pins.


	


Hi Paul,

Boy are you going to get action out of this one.  I was trained by an old 

Airforce Col.

  If it has a part that moves or rotates on the bolt, use a castle nut and 

cotter key. If it snugs down and holds compression, use a nyloc. If it gets hot, 

use a metal lock.



BTW, Although pricey, there is a nyloc castle nut available. I like them for 

the control stick position because if your cotter key goes you still have a 

nyloc. My feeling is that if it gets loose it  will take a while to back off.



Steve B

FF #007

luther b green

Joined: 10 Jan 2006
Posts: 47

Posted: Fri Jan 13, 2006 4:37 pm Post subject: nuts n bolts

Hi Paul, if you want to use the lock nut use the next size longer AN bolt. 

You can add up to three AN washers to get the threads right and still be 

correct per FAA. All that said if it were my plane I would use the drilled 

bolt as per plans. If you bend the cotter pin correctly it should not hang 

on anything.

Bryan Green (Elgin SC)

---

_________________
Bryan Green Elgin SC
Firestar 447 Powerfin

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Jan 13, 2006 5:57 pm Post subject: Re: nuts n bolts

 	  neilsenrmf(at)comcast.net wrote: 	
		  



As for cutting additional 

threads, I did this a few times but is it OK?



Rick Neilsen

Redrive VW powered MKIIIc



--- 	




No its not OK !!!   You will make a sharp cut into the bolt where a crack can easily start       Your cut bolt will be much weaker than it was designed to be

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

rsanoa

Joined: 10 Jan 2006
Posts: 71
Location: Bell Buckle,TN

Posted: Fri Jan 13, 2006 6:20 pm Post subject: nuts n bolts

I believe AN bolt threads are 'roll' cut. All threads on the flying wires on my Aeronca C3's were rolled instead of die cut. Die cut threads are much more susceptible to fatigue cracking. Someone may challenge me on the AN bolts but I'm on firm ground on the Aeronca wires.

  Ray .. Tenn.

  UltraStar

  Do not archive



JetPilot <orcabonita(at)hotmail.com> wrote: 

  

neilsenrmf(at)comcast.net wrote:

 	  Quote: 	
		   

 

 As for cutting additional 

 threads, I did this a few times but is it OK?

 

 Rick Neilsen

 Redrive VW powered MKIIIc

 

 ---


	




No its not OK !!! You will make a sharp cut into the bolt where a crack can easily start [Shocked] Your cut bolt will be much weaker than it was designed to be [Evil or Very Mad]



--------

NO FEAR - If you have no fear you did not go as fast as you could have !!!





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=3793#3793

  

		

---------------------------------

 Photo Books. You design it and well bind it!

_________________
Ray S.Anderson

Paul Petty

Joined: 11 Jan 2006
Posts: 226
Location: Mississippi

Posted: Sat Jan 14, 2006 5:47 am Post subject: Re: nuts n bolts

Thanks for the tips guys. When I read what should be done or why a certian method should be used, I follow instructions. Avaition is a new world to me. I have learned that "things" happen to airplanes that never happen to other vehicles. I asume that this bolt method is a result of testing and or failure at some point. Just for the hell of it if any of you care to take time, explain the 3 washer deal. So you wont think I'm a complete idiot, Let me give you some background on yours truely  .

My involement with "moving" parts began at the early age of 5 when my father gave me my first home made motorcycle. He knew i liked to ride my bicycle with "no hands" and warned me that this new motorcycle would not allow such. Well I didnt beleive him and as soon as I was out of his watchfull eye (he only had one) I tested his "theory" He was right! 

My entire life I have built,raced,crashed motorcycles,boats and gocarts.

With this background, you can see why I cant see why a "rotating" bolt with a drilled end and cotter pin is better than a nyloc nut. But because thats the required method I will obey! Think about the old days with cars that had drilled spindles with cottor pins. They fell off all the time. I have never heard of a wheel falling off a front wheel drive vehicle with a lock nut  One more thing and I will go back in my corner and finish this Kolb. Airplanes in general "construction wise" blow my mind. Example, This Kolb has a massive 1/2" bolt that goes through the spar into a tiny tang that then has a super tiny pin that holds our wings on. I trust it. Understand it? No sheesh! 



Take care guys

_________________
Paul Petty
Kolbra #12
Ms Dixie
912 UL 70" warp

Don G

Joined: 10 Jan 2006
Posts: 156
Location: Central Illinois

Posted: Sat Jan 14, 2006 3:42 pm Post subject: Re: nuts n bolts

Petty...



HEHe...you ha dme laughing on this one pard...and I know it doesnt make alot of sense...

snip.....""" Just for the hell of it if any of you care to take time, explain the 3 washer deal. So you wont think"""



the 3 washers are so you can get the required 3 threads if the bolt is too long... 

In true gov fashion....they have never told us why 5 threads are not as good as 3...but they have told us we can washer it up to get to their requirement...I remember when I learned this back in school....made me laugh then too!

_________________
Don G.
Central Illinois
Kitfox IV Speedster
Luscombe 8A
RV9A

dpaule(at)frii.com
Guest

Posted: Sun Jan 15, 2006 10:00 am Post subject: nuts n bolts

Don't want to over work the issue, but there are few guidelines:



If the bolt is primarily loaded in tension, more washers are slightly better

than fewer, because they add axial stiffenss to the parts of the joint

compared to the bolt itself, and under preload, that means that

proportionally more of the load will go through the joint. But the effect

disappears as you add more total washer thickness than the thickness of the

washer's wall, in this case looking at a washer as if it were a piece of

tube.



If the bolts are primarily loaded in shear, then make certain that the

threads are not in shear. Once that's done, minimise the amount of washers

because more washers generally add length to the moment arm that puts the

bolts in bending. You don't want to increase bending in a bolt.



Don't ever cut threads on aircraft bolts.



Dave Paule

Boulder, CO

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