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Rear spar alignment flaw and Warning

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jchang10

Joined: 05 Jul 2006
Posts: 227

Posted: Fri Feb 23, 2007 10:19 am Post subject: Rear spar alignment flaw and Warning

Has anyone else dealt with this issue? I am on page 16-2 on the Top Wing Skins

section. My left wing lined up perfectly. On the right wing, to my surprise, I

have an alignment problem between the top wing skin and the rear spar.



Here are some photos to illustrate...



Every other hole lines up between the top wing skin and the wing skeleton,

except for the inboard rear spar holes. The holes are out of alignment and

gradually come closer into alignment until they are lined up perfectly again

between the 4th and 5th rib, counting the root rib as rib #1. 

http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4481.html



Broader picture of the general area...

http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4482.html



The inboard most hole is the furthest out of line by about 1/16". The rear spar

hole needs to come further aft by 1/16".



I then did a lot of measuring to compare my left wing (perfect) with right wing

(problem). The problem appears to be with the rear spar. The upper flange seems

to taper from 22/32" wide down to 20/32" wide at the inboard edge, which would

account for the 1/16" alignment error in the top skin.



Photo of rear spar top flange on left (correct side):

http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4483.html



Photo of rear spar top flange on right (error side):

http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4484.html



I spoke with Van's this morning. They made 2 recommendations:



  1. Does the bottom skin line up? Answer: surprisingly enough, YES. It's not

perfect, but will be manageable.



  2. Drill and rivet the misaligned holes with 1/8" rivets.



The problem with this solution is that the new hole will have an edge-distance

problem. I should have 1/4" clearance to the edge, but I will only have 3/16"

clearance to the aft edge on the rear spar. As I work outboard, the edge

distance issue should get better and better, but still not within spec.



1/16" would not be a problem anywhere else on the wing, as far as I can tell. I

could have "massaged" things possibly by that amount. However, this problem is

at the wing root and wing walk area, which is heavily reinforced. There is no

"massaging" possible here.



Finally, I could get a new rear-spar, however, that means removing all of the

doublers and tons of AN470AD4-8 and 4-6 rivets!!!



Thus, the warning to other builders, BEFORE riveting the rear spar, measure the

top flange on your rear spar, to make sure it stays even in width. Even better,

try fitting the top skin on before riveting the rear spar.



Can anyone provide any other recommendations?



Another thought is, can I somehow put in a shim between the rear spar and the 2

inboard ribs? The shim would have to only be along the top holes, since the

bottom holes are lined up.



Thanks,



Jae

_________________
#40533 RV-10
First flight 10/19/2011
Phase 1 Done 11/26/2011

orchidman

Joined: 10 Jul 2006
Posts: 277
Location: Oklahoma City - KRCE

Posted: Fri Feb 23, 2007 10:35 am Post subject: Re: Rear spar alignment flaw and Warning

Jae,

I may be coming up on this point in about a month.  What was the serial # of your wing spars and how long have you had them?

My builder # is 40674 but my spar # is 10578 which I think means that I have the 578th wing kit shipped.

_________________
Gary Blankenbiller
RV10 - # 40674
(N2GB Flying)

kdbelue(at)charter.net
Guest

Posted: Fri Feb 23, 2007 10:55 am Post subject: Rear spar alignment flaw and Warning

Jae,



I had the same problem (about 2 years ago). My rear spar flange was off more 

than yours, though. Van's sent me another spar and I drilled out all the 

rivets and replaced it. It looks like you can use yours - I would drill the 

holes to match and use the "oops" rivets if necessary. It's a good idea for 

everyone to check the dimensions on the rear spar before rivetting because 

it is a big job to remove it.



Kevin Belue

RV-6A flying

RV-10 finish

---

jchang10

Joined: 05 Jul 2006
Posts: 227

Posted: Fri Feb 23, 2007 12:35 pm Post subject: Rear spar alignment flaw and Warning

Kevin... Well, I just hope we can help this from happening to anyone else. I

have already ordered a replacement left rear spar. Even the replacement was not

the SAME as my original. With these discrepancies, I think there are plenty of

quality control issues on the rear spars



At this point, I am leaning towards upsizing to 1/8" hole and rivets. However,

what can I do to deal with the edge-distance clearance issue? Does anyone have

any recommendations?



My thoughts are:



1. Just leave it alone. It's just 1/16" under the edge distance clearance for a

1/8" rivet.



2. Add some extra 3/32" holes and rivets in rear spar upper flange. The current

spacing between holes is 26/32". If I put another hole in between existing

holes, is that safe to do?



Thanks again for the suggestions,

Jae



--

_________________
#40533 RV-10
First flight 10/19/2011
Phase 1 Done 11/26/2011

jchang10

Joined: 05 Jul 2006
Posts: 227

Posted: Fri Feb 23, 2007 2:51 pm Post subject: Rear spar alignment flaw and Warning

Hi Gary,



The spar # is 10495. I received it in June 2006.

My builder # is 40533.



I would make sure to measure the upper flange width, to make sure it is

consistent along the entire length of the rear spar.



Jae

Do not archive



--

_________________
#40533 RV-10
First flight 10/19/2011
Phase 1 Done 11/26/2011

owl40188(at)yahoo.com
Guest

Posted: Fri Feb 23, 2007 2:53 pm Post subject: Rear spar alignment flaw and Warning

Hi Jay,

  

 I think you will be fine going with 1/8 inch rivets.

  

 You would have reduced your allowable bearing stress on the spar by about 30% due to the shorter edge distance but you will have gained about that much from the higher bearing area.  By the way, 1.5D is not considered short edge distance.  Many pieces of structure are designed to that edge distance.  I am assuming you are measuring from the center of the hole to the edge of the part.  Additionally depending on the thickness of the parts the spar might not be the weakest link.

  

  

 The net area on the spar will be slightly reduced so the spar will be weaker by the difference in the area of the upper flanges which is pretty small.  Also the upper spar is usually in compression which minimizes the effect.

  

 I don't think its a problem but you might want to check with Vans anyway.  Do make sure though that you get good holes and no "figure 8s"

  

 Niko

 40188

 ---

jchang10

Joined: 05 Jul 2006
Posts: 227

Posted: Fri Feb 23, 2007 4:47 pm Post subject: Rear spar alignment flaw and Warning

Niko... Vans is recommending using oops rivets, so i think that would

definitely mean a weaker structure than using the original callout. Part

of the reason, is because this is a tight access area, because of the

built-up doublers in the way.



Finally, Vans brought up another issue. The 1/16" missing from the upper

flange had to have gone somewhere. Yep, it went into the web of the spar.

There is now quite a gap created above the ribs.



This is the gap in the right (problem side) root rib. That is almost 1/8"

thick. 0.125". The top skin is .032". That means the shim I would have to

use to fill that gap will be 3 to 4 times the thickness of the top skin.

http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4485.html



This is another inner rib, all the inner ribs have the same problem, up to

the 5th rib, which is fine.

http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4486.html



As a comparison, this is what my left root rib looks like - what it should

be.

http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4487.html



I am going to have to think about this over the weekend. Now, i am leaning

towards replacement.



Any opinions on what others would do?



That hissing sound i hear is the sound of building momentum leaking away

again!



Jae



[quote] Hi Jay,



 I think you will be fine going with 1/8 inch rivets.



 You would have reduced your allowable bearing stress on the spar by about

 30% due to the shorter edge distance but you will have gained about that

 much from the higher bearing area.  By the way, 1.5D is not considered

 short edge distance.  Many pieces of structure are designed to that edge

 distance.  I am assuming you are measuring from the center of the hole to

 the edge of the part.  Additionally depending on the thickness of the

 parts the spar might not be the weakest link.

 The net area on the spar will be slightly reduced so the spar will be

 weaker by the difference in the area of the upper flanges which is pretty

 small.  Also the upper spar is usually in compression which minimizes the

 effect.



 I don't think its a problem but you might want to check with Vans anyway.

 Do make sure though that you get good holes and no "figure 8s"



 Niko

 40188

 ---

_________________
#40533 RV-10
First flight 10/19/2011
Phase 1 Done 11/26/2011

orchidman

Joined: 10 Jul 2006
Posts: 277
Location: Oklahoma City - KRCE

Posted: Sat Feb 24, 2007 6:09 pm Post subject: Re: Rear spar alignment flaw and Warning

 	  jchang10 wrote: 	
		  Hi Gary,



The spar # is 10495. I received it in June 2006.

My builder # is 40533.



I would make sure to measure the upper flange width, to make sure it is

consistent along the entire length of the rear spar.



Jae

-- 	


Jae,

I measured my spars which are still on the shelf.  Measuring as you did in the pictures IMG 4483 & 4484, I found that all of mine were 22/32 for both the top and bottom flanges.  I did find one area that might have been off by as much as 1/32 giving a measurement of almost 23/32.

My measurements were taken by placing a block on the back side of the WEB as you did with your yellow tool and then measuring the flange.

I also attached a couple ribs and they seemed to fit just right.  Hopefully they have got their problems fixed.

_________________
Gary Blankenbiller
RV10 - # 40674
(N2GB Flying)

owl40188(at)yahoo.com
Guest

Posted: Mon Feb 26, 2007 6:56 am Post subject: Rear spar alignment flaw and Warning

Hi Jae,

  

 Sorry to see you are having such a problem with your rear spar.

  

 After seeing your latest pictures I would replace the rear spar.  Not that it couldn't be fixed but you are going to put a lot of time into fixing it with shims, you won't be totally happy with it and then you might still run into unforseen problems when you mount your ailerons and flaps because of the taller aft spar.  You would be in effect changing the airfoil shape.  One you start drilling out the rivets you might find its going fairly fast and you haven't lost all that much time.

  

 Good luck with it.

  

 Niko

 40188

 ---

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Wed Mar 07, 2007 5:21 am Post subject: Rear spar alignment flaw and Warning

Jae, sorry I was out for a while and just going back through mail that I 

missed. I had a similar problem with one of the rear spars that was not 

bent/formed correctly and resulted in a slight taper  (3/32 - 1-16") in 

the spar cap on one of the ends. It throws off a lot of other stuff, 

Van's sent me a new one.



Deems Davis # 406

Finishing - ( A Misnomer ! )

http://deemsrv10.com/



Jae Chang wrote:

 	  Quote: 	
		   



 Niko... Vans is recommending using oops rivets, so i think that would

 definitely mean a weaker structure than using the original callout. Part

 of the reason, is because this is a tight access area, because of the

 built-up doublers in the way.



 Finally, Vans brought up another issue. The 1/16" missing from the upper

 flange had to have gone somewhere. Yep, it went into the web of the spar.

 There is now quite a gap created above the ribs.



 This is the gap in the right (problem side) root rib. That is almost 1/8"

 thick. 0.125". The top skin is .032". That means the shim I would have to

 use to fill that gap will be 3 to 4 times the thickness of the top skin.

 http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4485.html



 This is another inner rib, all the inner ribs have the same problem, up to

 the 5th rib, which is fine.

 http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4486.html



 As a comparison, this is what my left root rib looks like - what it should

 be.

 http://www.jline.com/log/aviation/build/wingkit/photos/IMG_4487.html



 I am going to have to think about this over the weekend. Now, i am leaning

 towards replacement.



 Any opinions on what others would do?



 That hissing sound i hear is the sound of building momentum leaking away

 again!

ericparlow(at)hotmail.com
Guest

Posted: Wed Mar 07, 2007 7:00 am Post subject: Rear spar alignment flaw and Warning

Has anyone had the 430/530 WAAS conversion done and installed it?



We need to know if there were any modification needed to the plane's wiring 

or antennas.



It's been suggested that RG-58 is not acceptable and the cable length is 

critical.  Also that the antenna needs to change.



ERic--

RV-10, 40014

N104EP

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