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Freak accident

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undoctor

Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA

Posted: Tue Aug 04, 2009 5:23 pm Post subject: Freak accident

I had an incident today I'd like to share both as a heads-up, and also 

looking for advice.



When I came in today I taxied up to my hanger/trailer.  I gave it a 

little throttle to get a bit closer and it seemed the engine didn't idle 

back when I pulled the throttle back.  I put more pressure on the 

throttle to close it, and when I did, the engine revved up.  Pressing 

the heel brakes kept it slow but I couldn't stop it and the right wing 

bumped the back of the trailer, putting a flat spot about 1" high by 

about 2" wide on the leading edge of my right wing about three and a 

half feet from the root.



First, what I found out caused the mishap.  Picture the throttle handle; 

when you push the throttle forward, the cable comes out of the cable 

housing straight forward.  When you bring the handle back to idle, the 

cable re-enters the cable housing straight back.  But when you move the 

throttle handle even further back (which is what I did in my sudden 

attempt to get the engine back to idle), it begins to pull the cable 

back out of the housing, straight down; which pulls the throttle on and 

you hit the trailer.  To be forewarned...



Now, the fix.  There is nothing involved except a misshaped leading 

edge.  I'm thinking if I get a piece of hardwood turned that I can slip 

into the tube from the root, when I reach the dent, I could gently tap 

it in and return the leading edge to the proper cylindrical shape.  Kind 

of like the dies used to return an exhaust pipe to round.  The wood is 

hard enough to bend the tubing out, but it won't scratch the inside of 

the tube as it's reshaping it.



So, what do you think?  Any input, cautions, other ideas, etc., will be 

enormously appreciated.



Dave Kulp

Bethlehem, PA

FireFly 11DMK

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Aug 04, 2009 6:10 pm Post subject: Freak accident

At 09:23 PM 8/4/2009, Dave Kulp wrote:

 	  Quote: 	
		  ...the right wing bumped the back of the trailer, putting a flat spot 

about 1" high by about 2" wide on the leading edge of my right wing about 

three and a half feet from the root... I'm thinking if I get a piece of 

hardwood turned that I can slip into the tube from the root, when I reach 

the dent, I could gently tap it in and return the leading edge to the 

proper cylindrical shape...


	


Wouldn't the rivets holding the ribs to the leading edge prevent the wood 

from going in?



Not sure it's an issue anyay.  There's a similar dent on the LE of my 

UltraStar, was there when I bought it.  Aside from cutting and peeling the 

fabric back around it to make sure there was no crack, I haven't worried 

about it.  There's not a lot of stress on the LE tube anyway (it would be a 

very different story on something like a Quicksilver where the LE tube IS 

the spar).



Sounds like what you really need is a stop to limit the throttle lever travel.



-Dana



--

  "A designer knows he has achieved perfection not when there is nothing 

left to add, but when there is nothing left to take away." -Antoine de 

Saint-Exup,ry

Kip

Joined: 13 Jul 2009
Posts: 51

Posted: Tue Aug 04, 2009 6:14 pm Post subject: Re: Freak accident

Shouldn't the carb spring try to pull the cable back into the housing? Or, perhaps the cable attatch point is not able to pivot freely at the throttle...?

_________________
2000 Firestar II
R503 DCDI
VLS 750

2010 Waiex
Jabiru 3300

2020 Pitts Special S-1C

John Hauck

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

Posted: Tue Aug 04, 2009 6:22 pm Post subject: Freak accident

There's not a lot of stress on the LE tube anyway (it would be a

 	  Quote: 	
		   very different story on something like a Quicksilver where the LE tube IS 

 the spar).


	


 > -Dana

Dana:



Might better take another look at the leading edges of your Kolb wings.



I think the leading edges and the first 18 or so inches back to the main 

spar carry most of the load of the aircraft.



One of the main reasons I put a lot of emphasis on keeping those little 

.028" wall 5/16" ribs in column by insuring there is more than enough 

lateral bracing to keep them in column.  On your Ultrastar and my long gone 

FS, there are/were only 5 of those little guys carrying each wing panel.



The leading edge tube on the Ultrastar was also shipped with .028" wall 

tubing.



Old Kolb Company made a tool to push dents out of the leading edge without 

dismantling the wing.  I put a big dent in the leading edge of my FS when a 

windshield split and departed the aircraft in flight.  When I made the new 

replacement windshield I didn't know it was acrylic.  I was told it was 

lexan.



john h

mkIII

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

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Tue Aug 04, 2009 6:43 pm Post subject: Freak accident

At 10:22 PM 8/4/2009, John Hauck wrote:



 	  Quote: 	
		  Old Kolb Company made a tool to push dents out of the leading edge without 

dismantling the wing...


	


What did the tool look like, how did it work?



Still, a shallow dent with no sharp creases in the front of the LE won't 

have a dramatic effect on the bending strength of the tube in the direction 

of the loads it does see.  If the dent was on the top or bottom of the 

tube, or if there were sharp creases or cracks, I'd be much more concerned.



-Dana



--

  "A designer knows he has achieved perfection not when there is nothing 

left to add, but when there is nothing left to take away." -Antoine de 

Saint-Exup,ry

aslsa.rng(at)gmail.com
Guest

Posted: Tue Aug 04, 2009 8:22 pm Post subject: Freak accident

John, I'm having difficulty with your concept of " the leading edges and the first 18 or so inches back to the main spar carry most of the load of the aircraft"  The leading edge is connected to the spar by the ribs but not the the fuselage or the spar carry through. I just don't see the load path. Would you elaborate? 



Rick Girard

do not archive

 

On Tue, Aug 4, 2009 at 9:37 PM, Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)> wrote:

[quote] --> Kolb-List message posted by: Dana Hague <d-m-hague(at)comcast.net (d-m-hague(at)comcast.net)>

 



 At 10:22 PM 8/4/2009, John Hauck wrote:

 

  	  Quote: 	
		   Old Kolb Company made a tool to push dents out of the leading edge without dismantling the wing...

 	
 

 What did the tool look like, how did it work?

 

 Still, a shallow dent with no sharp creases in the front of the LE won't have a dramatic effect on the bending strength of the tube in the direction of the loads it does see.  If the dent was on the top or bottom of the tube, or if there were sharp creases or cracks, I'd be much more concerned. 

 

 -Dana

 

 --

  "A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away." -Antoine de Saint-Exup,ry

 

 

 ===========

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

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

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

 ===========

 

 

 

 



[b]

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Wed Aug 05, 2009 2:42 am Post subject: Re: Freak accident

 	  undoctor wrote: 	
		  I had an incident today I'd like to share both as a heads-up, and also 

looking for advice.



When I came in today I taxied up to my hanger/trailer.  I gave it a 

little throttle to get a bit closer and it seemed the engine didn't idle 

back when I pulled the throttle back.  I put more pressure on the 

throttle to close it, and when I did, the engine revved up.  Pressing 

the heel brakes kept it slow but I couldn't stop it and the right wing 

bumped the back of the trailer, putting a flat spot about 1" high by 

about 2" wide on the leading edge of my right wing about three and a 

half feet from the root.



First, what I found out caused the mishap.  Picture the throttle handle; 

when you push the throttle forward, the cable comes out of the cable 

housing straight forward.  When you bring the handle back to idle, the 

cable re-enters the cable housing straight back.  But when you move the 

throttle handle even further back (which is what I did in my sudden 

attempt to get the engine back to idle), it begins to pull the cable 

back out of the housing, straight down; which pulls the throttle on and 

you hit the trailer.  To be forewarned...



Now, the fix.  There is nothing involved except a misshaped leading 

edge.  I'm thinking if I get a piece of hardwood turned that I can slip 

into the tube from the root, when I reach the dent, I could gently tap 

it in and return the leading edge to the proper cylindrical shape.  Kind 

of like the dies used to return an exhaust pipe to round.  The wood is 

hard enough to bend the tubing out, but it won't scratch the inside of 

the tube as it's reshaping it.



So, what do you think?  Any input, cautions, other ideas, etc., will be 

enormously appreciated.



Dave Kulp

Bethlehem, PA

FireFly 11DMK 	




My FSII had a couple dents in one of the leading edges from when the original builder had to put it down in some Mesquite trees after an engine-out (at only 6 hours, ouch - he was totally devastated and the pictures in the builders log were just painful to look at). They weren't deep enough to actually compromise the spar tho and didn't actually bend anything up. So he just flew it like that after the repairs for the next 400 hours (and I flew it like that for another 100 or so ).



As for the throttle cable, I'd go ahead and replace it if the carb slides can't retract the cables easily and completely. You can mitigate it for a while with silicone lube, but that generally means the inside of the housing is worn and giving friction which it shouldn't.



On my FSII, the builder put stops on the throttle quadrant to prevent it from going too far in either direction. The stops should correspond with the limits of travel of the slide, especially in the full open position - if you're able to force it past full open the results can be extremely expensive.....



LS

_________________
LS
Titan II SS

Ralph B

Joined: 14 Apr 2007
Posts: 367
Location: Mound Minnesota

Posted: Wed Aug 05, 2009 3:24 am Post subject: Re: Freak accident

I have just the solution for you. For small dents, use the Poly Fiber light weight epoxy. Take the finishing tape off the leading edge if you have it, apply the epoxy liberally, sand to a smooth finish, apply new tape, and paint. I sanded mine by hand and made a template of cardboard to check the leading edge curve as I was sanding. If you do it right, it looks like there never was a dent.



Ralph B

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Ralph B

Kolb Kolbra 912uls
N20386
550 hours

John Hauck

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

Posted: Wed Aug 05, 2009 5:09 am Post subject: Freak accident

> What did the tool look like, how did it work?

 	  Quote: 	
		  

 > -Dana
	


Not easy to explain and describe.  Wish I had a photo of it.



The tool was made in two parts of 4130 tubing, cut at a long gentle angle, 

catty-corner long ways from end to end.  Sheet metal faces were then welded 

to both cut sides.  A steel rod was welded to each piece of the tool.



The tool was inserted into the inboard end of the leading edge tube, one 

piece at a time.  The two beveled pieces were then pulled together forcing 

the dent out.



The split pieces allowed the user to insert the tool past the rivets.



john h

mkIII

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

John Hauck

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

Posted: Wed Aug 05, 2009 5:20 am Post subject: Freak accident

The area of the wing that works the hardest is from  the leading edge rearward to the main spar.  

  

 My 5 rib FS carried the aircraft with 10 rib noses  made of .028" wall 5/16" aluminum tubing, 5 on each wing panel.  That ain't  much for the way I asked my FS to work.

  

 In order for the wing sections to work correctly,  those little rib noses have to be kept in column.  One of the primary jobs  of the leading edge is to help keep the rib noses in column.  If the  leading edge bends/shifts laterally, it pulls the noses out of column.   Lateral bracing of the leading edge is extremely important.

  

 The 5/16" tubing called for in the plans of the US  and FS for lateral bracing had a habit of breaking due to vibration and  stress.  Once these broke, the only thing holding the rib noses in column  was the bow tip.

  

 Some years ago I posted some photos of the results  of leading edge failure of both wings of my FS, which failed up and rearward to  the main spar, in flight of course.

  

 I'd resend the photos of the failure, but I don't  know exactly what DVD they are on or where it is right now.

  

 john h

 mkIII

  

 [quote]    

John, I'm having difficulty with    your concept of " the leading edges and the first 18 or    so inches back to the main spar carry most of the load of the aircraft"     The leading edge is connected to the spar by the ribs but not the the    fuselage or the spar carry through. I just don't see the load path. Would you    elaborate?   



   Rick    Girard

    

[b]

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

undoctor

Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA

Posted: Wed Aug 05, 2009 6:42 am Post subject: Freak accident

Not sure it's an issue anyay.  There's a similar dent on the LE of my

      UltraStar, was there when I bought it.  Aside from cutting and 

peeling the

      fabric back around it to make sure there was no crack, I haven't 

worried

      about it.  There's not a lot of stress on the LE tube anyway (it 

would be a

      very different story on something like a Quicksilver where the LE 

tube IS

      the spar).

     

      Sounds like what you really need is a stop to limit the throttle 

lever travel.

     

      -Dana

Dana, John, Kip, Rich,



Thanks for your input.  Though I'm not educated in engineering, the 

logic of my thinking was that it isn't a critical issue, and no one is 

screaming "DON'T FLY IT."  Quite a relief.



After I get a wood shop to turn the wood "ramrod" I'd envisioned, I plan 

on running it through my table saw and putting a kerf along it's length 

to accommodate the rivets.  I also plan on rounding the leading edge (of 

the ramrod) to gently push the indent out, rather than a square edge, 

which would tend to "suddenly" push it out and stress the metal at the 

bend points.



But, if anyone knows anyone who has the tool mentioned, I'd love to pay 

freight here and back to use that rather than "building" a wood ram.  

I'd had it mentioned to me; goes in narrow and once in place you turn a 

screw mechanism which spreads the two halves.  If no one knows of one in 

the system it might be a good investment for a machinist to make one to 

rent out, from the way it sounds!



10/4 on the stop, Dana!  Never even crossed my mind that that could 

happen, but it certainly is a consideration now!  Kip, the carb does 

pull the cable back in, but I have the throttle tensioned like a GA so I 

can leave go of the throttle when I'm at altitude and maintain my RPM 

setting.  This occurred because the throttle handle has no stop and I 

went past the point where the cable was all the way into the housing and 

began to pull back out when I was required to act very hastily and went 

beyond the idle position.  And John, it sounds like Fortune is your 

co-pilot.  The windshield could have put a serious dent in your face 

when it departed, rather than the leading edge of your wing!!



Again, thanks to all of you, sure is nice to have tons of hours 

experience available for things like this.  And if anyone knows the 

whereabouts of an Undenting Machine I'd love to be put in touch with it.



Dave Kulp

Bethlehem, PA

FireFly 11DMK

mdnanwelch7(at)hotmail.co
Guest

Posted: Wed Aug 05, 2009 8:16 am Post subject: Freak accident

John C

  

   Very good description.  I C too C have a small dent in my leading edge tube that I need to push back out.  The tool you describe is pretty much what I intended on building.

   Essentially C the tool functions much like a muffler pipe expansion tool....only it's fashioned to be at the end of a piece of metal rod.

  

 Mike Welch

 MkIII  collecting dust

  

 

 

 	  Quote: 	
		   From: jhauck(at)elmore.rr.com

 To: kolb-list(at)matronics.com

 Subject: Re: Freak accident

 Date: Wed C 5 Aug 2009 08:02:37 -0500

 

 --> Kolb-List message posted by: "John Hauck" <jhauck(at)elmore.rr.com>

 

 

 > What did the tool look like C how did it work?

 >

 > -Dana

 

 

 Not easy to explain and describe. Wish I had a photo of it.

 

 The tool was made in two parts of 4130 tubing C cut at a long gentle angle C 

 catty-corner long ways from end to end. Sheet metal faces were then welded 

 to both cut sides. A steel rod was welded to each piece of the tool.

 

 The tool was inserted into the inboard end of the leading edge tube C one 

 piece at a time. The two beveled pieces were then pulled together forcing 

 the dent out.

 

 The split pieces allowed the user to insert the tool past the rivets.

 

 john h

 mkIII 

&gt==============
	


[quote] 

 

 

Get your vacation photos on your phone! Click here.   	  Quote: 	
		  [b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Aug 05, 2009 9:04 am Post subject: Freak accident

At 09:02 AM 8/5/2009, John Hauck wrote:



 	  Quote: 	
		  Not easy to explain and describe.  Wish I had a photo of it.



The tool was made in two parts of 4130 tubing, cut at a long gentle angle...


	


Thanks John, your explanation makes perfect sense.



-Dana



do not archive

--

  If one synchronized swimmer drowns, do the rest have to drown too?

Possums

Joined: 03 Nov 2007
Posts: 247

Posted: Wed Aug 05, 2009 3:36 pm Post subject: Freak accident

At 12:53 PM 8/5/2009, you wrote:

 	  Quote: 	
		  



At 09:02 AM 8/5/2009, John Hauck wrote:



>Not easy to explain and describe.  Wish I had a photo of it.

>

>The tool was made in two parts of 4130 tubing, cut at a long gentle angle...



Thanks John, your explanation makes perfect sense.



-Dana


	




Tool = $31.00



http://www.jcwhitney.com/MUFFLER-PIPE-EXPANSION-TOOL/GP_2004125_N_111+200005119+600017965_10614.jcw

_________________
Possum

undoctor

Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA

Posted: Thu Aug 06, 2009 1:36 pm Post subject: Freak accident

[quote][b] 

       > What did the tool look like, how did it work?

      >

       > -Dana

      

      

      Not easy to explain and describe.  Wish I had a photo of it.

      

      The tool was made in two parts of 4130 tubing, cut at a long gentle angle, 

      catty-corner long ways from end to end.  Sheet metal faces were then welded 

      to both cut sides.  A steel rod was welded to each piece of the tool.

      

      The tool was inserted into the inboard end of the leading edge tube, one 

      piece at a time.  The two beveled pieces were then pulled together forcing 

      the dent out.

      

      The split pieces allowed the user to insert the tool past the rivets.

      

      john h

      mkIII 



Great explanation, John.  Very easy to picture.  Ever considered writing as a career???



Now, if you know where one of these is hiding...



Dave Kulp

Bethlehem, PA

FireFly 11DMK

[/b][b]

undoctor

Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA

Posted: Thu Aug 06, 2009 1:41 pm Post subject: Freak accident

Thanks to all contributors for your ideas for fixing the LE dent.  I 

surely appreciate them all and I'll bet there are

some others on the list who do, too.



Dave Kulp

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