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Cracked tail post fix

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Jimmy Young

Joined: 24 Nov 2007
Posts: 182
Location: Missouri City, TX

Posted: Sun Jan 31, 2010 4:29 pm Post subject: Cracked tail post fix

List,

 

My tail post cracked, same place as other Kolbs have as has been previously noted on the list. The junction at the vertical tail post and horizontal tube that welds to the bottom of the tail ring is where it let go. We sleeved the inside with a 4130 tube and welded it up. I also replaced the very weak diagonal "lawn-chair" grade aluminum tubing that forms the bottom of the lower vertical stabilizer with a piece of 3/4 X .049 AL tubing, as the original piece was cracked in two as well. That original piece is some really thin stuff,  but maybe all that's required of it is to hold the fabric. I just couldn't go back with something that thin.



I thought about the fabric work left to do for a bit, then decided I'd try aluminum instead. Worked out pretty good, easier than the fabric work would have been, plus I can take it off via screws for future inspection. I've included a photo of what I did. 



I will take a look at adding the struts as some have done, but to me that mod looks like the angle is so steep you're not gaining much strength. I think a full-swivel tailwheel is the better option to relieve the lateral forces placed on this part of the plane.



Looking forward to warmer, drier weather something fierce! I've done very little flying since November.



Jimmy Young

Houston TX

FS II, 405 ttl hrs, 295 my hrs, 70 hrs on HKS

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Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun Jan 31, 2010 4:57 pm Post subject: Cracked tail post fix

> I will take a look at adding the struts as some have done, but to me that 

mod looks like the angle is so steep you're not gaining much strength. I 

think a full-swivel tailwheel is the better option to relieve the lateral 

forces placed on this part of the plane.

 	  Quote: 	
		  

 > Jimmy Young
	


Jimmy Y/Gang:



Rethink using the strut braces.  I haven't had a problem with my tailpost 

since we made that mod.



Take a close look at the Kolb tailpost.  There is no lateral bracing except 

the top and bottom weld on the tail boom ring.  The wire bracing does 

nothing to add strength or lateral bracing to the tail post.  Wire bracing 

maintains proper spacing of the vertical and horizontal stabilizers.



A full swivel tail wheel will not eliminate lateral stress to the tail post.



Worth what you paid for it....



john hauck

mkIII

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Sun Jan 31, 2010 5:20 pm Post subject: Cracked tail post fix

Jimmy Y/Gang:



Rethink using the strut braces.  I haven't had a  problem with my tailpost 

since we made that mod.



Take a close look at  the Kolb tailpost.  There is no lateral bracing except 

the top and  bottom weld on the tail boom ring.  The wire bracing does 

nothing to  add strength or lateral bracing to the tail post.  Wire bracing  

maintains proper spacing of the vertical and horizontal  stabilizers.



A full swivel tail wheel will not eliminate lateral stress  to the tail post.



Worth what you paid for it....



john  hauck

mkIII

Titus, Alabama 



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

  

 Yeah, I had a full swivel tail wheel and it still broke.  John is right, there is no way that post from the ring is up to the stresses we  put on it.

 Larry

 nbsp;       Navigator  Photoshare, and  href="http://www.matronics.com/Navigator?Kolb-List">http://www.matronicp;     the Web  href="http://forums.matronics.com">http://forums.matronics.com

_p;          generous  bsp;                     href="http://www.matronics.com/contribution">http://www.matronics.com/c=================



 [quote]   

     - www.avg.com 

Version: 8.5.432 / Virus    Database: 271.1.1/2660 - Release Date: 01/31/10  19:35:00

[b]

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NeilsenRM(at)comcast.net
Guest

Posted: Sun Jan 31, 2010 5:47 pm Post subject: Cracked tail post fix

Jimmy



I took the queue from John and added some bar stock 1/16 X 1" aluminum 

between the fuselage tube and my lower vertical stabilizer. This might not 

be quite as strong as what John did but my tail post hasn't cracked yet and 

I tend to be king of hard on it. I felt that it was worth doing to keep from 

future problems. Never saw the need to experience a problem when others have 

already detected a problem and have a fix. The fix really strengthen my tail 

post.



Rick Neilsen

Redrive VW Powered MKIIIC



---

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun Jan 31, 2010 7:25 pm Post subject: Cracked tail post fix

> I took the queue from John and added some bar stock 1/16 X 1" aluminum

 >

 	  Quote: 	
		   Rick Neilsen


	


Rick N/Gang:



Gary Haley used 1/8" X 1 aluminum strap.  Worked good, til he broke his 

airplane at MV last year.



Might work a little better for you.  Easy to duplicate.  You can use the old 

ones for patterns.



john hauck

mkIII

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

zeprep251(at)aol.com
Guest

Posted: Mon Feb 01, 2010 5:54 am Post subject: Cracked tail post fix

Jimmy,

 I went through the same sequence of repairs as you.First noticed the cracked tube in the lower stabilizer,went with a heavier tube,then cracked the short horizontal steel tube going from the tail post to the lower part of the ring.removed the tail assy., welded it with a gusset.If you grab the tail spring and move it left and right you can see the twisting load on the ring/tail post assy. The straps from the lower stab.tube to the ring are are always in tension and eliminate that moment.I can't remember any other structural failure on the Kolbs,but John's fix ends this problem. I encourage you to reconsider.

    G.Aman FS2,MK3C

 

   

 

  

   

 

   

 

  --

rlaird

Joined: 10 Jan 2006
Posts: 373
Location: Houston

Posted: Mon Feb 01, 2010 6:00 am Post subject: Cracked tail post fix

Ah, so, the EAA sheet metal workshop paid off, eh?     Looks good!



On Sun, Jan 31, 2010 at 6:29 PM, Jimmy Young <jdy100(at)comcast.net (jdy100(at)comcast.net)> wrote:

 [quote]--> Kolb-List message posted by: "Jimmy Young" <jdy100(at)comcast.net (jdy100(at)comcast.net)>

 

 I thought about the fabric work left to do for a bit, then decided I'd try aluminum instead. Worked out pretty good, easier than the fabric work would have been, plus I can take it off via screws for future inspection. I've included a photo of what I did.

 

 [b]

_________________
~~~~~~~~~~~~~~~~~~~
Robert Laird
formerly: MkIIIc w/ 912ULS & Gyrobee
current: Autogyro Cavalon w/ 914ULS
Houston, TX area
http://www.Texas-Flyer.com

Jimmy Young

Joined: 24 Nov 2007
Posts: 182
Location: Missouri City, TX

Posted: Mon Feb 01, 2010 11:10 am Post subject: Re:Re: Cracked tail post fix

 	  Quote: 	
		  The fix really strengthen my tail 

post. 	
 



 	  Quote: 	
		  Rethink using the strut braces. I haven't had a problem with my tailpost 

since we made that mod. 	
 



 	  Quote: 	
		  I can't remember any other structural failure on the Kolbs,but John's fix ends this problem. 	




I have seen the light! I'm installing tailpost bracing asap. Thanks for the comments. I'll post a photo of the completed work.

_________________
Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700

frank.goodnight(at)att.ne
Guest

Posted: Mon Feb 01, 2010 12:35 pm Post subject: Cracked tail post fix

Hi Jim,

Fwiw [ for what it's worth] I think you made a good decision,

Frank  Goodnight

Firestar 2

On Feb 1, 2010, at 1:10 PM, Jimmy Young wrote:

 	  Quote: 	

> The fix really strengthen my tail

> post.

> Rethink using the strut braces. I haven't had a problem with my  

> tailpost

> since we made that mod.

> I can't remember any other structural failure on the Kolbs,but  

> John's fix ends this problem.

 I have seen the light! I'm installing tailpost bracing asap. Thanks  

 for the comments. I'll post a photo of the completed work.

 --------

 Jimmy Young

 Missouri City, TX

 Kolb FS II/HKS 700

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p 84410#284410

Fran Losey

Joined: 21 Feb 2009
Posts: 61
Location: Boca Raton, FL

Posted: Sat Feb 13, 2010 6:13 am Post subject: Cracked tail post fix

On 2/1/2010 9:00 AM, Robert Laird wrote:  	  Quote: 	
		  Ah, so, the EAA sheet metal workshop paid off, eh?     Looks good!   

   

   On Sun, Jan 31, 2010 at 6:29 PM, Jimmy Young   <jdy100(at)comcast.net (jdy100(at)comcast.net)> wrote:

    	  Quote: 	
		  --> Kolb-List message posted by: "Jimmy Young" <jdy100(at)comcast.net (jdy100(at)comcast.net)>

     

 I thought about the fabric work left to do for a bit, then decided I'd try aluminum instead. Worked out pretty good, easier than the fabric work would have been, plus I can take it off via screws for future inspection. I've included a photo of what I did.

     

   



 href="http://www.matronics.com/Navigator?Kolb-List">http://www.matronics.com/Navigator?Kolb-List

 href="http://forums.matronics.com">http://forums.matronics.com

 href="http://www.matronics.com/contribution">http://www.matronics.com/contribution



	
 	
 Could you resend your photo please?

 

 Thanks in advance.

 

 -- 

 Sincerely, Fran Losey [url=http://www.mykitlog.com\loseyf]www.mykitlog.com\loseyf[/url]

    [quote][b]

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Fran Losey
N62FL (reserved)

loseyf@comcast.net

Jimmy Young

Joined: 24 Nov 2007
Posts: 182
Location: Missouri City, TX

Posted: Sat Feb 13, 2010 3:25 pm Post subject: Re: Cracked tail post fix

Fran,



The photo is on the first post of this thread. At that time, I had not painted the aluminum.



If you are having trouble finding it, email me direct and I can send you more. I'll be at the hanger tomorrow & can take more detailed photos if you would like. I've got the stiffener struts made, but had to order a longer bolt so they are not on yet.



Jimmy Y

_________________
Jimmy Young
Missouri City, TX
Kolb FS II/HKS 700

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