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  #1  
Old 11-07-2013, 05:15 AM
dbhill916's Avatar
dbhill916 dbhill916 is offline
 
Join Date: May 2013
Location: Westerville, OH
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Default mis-drilled tie down

Hi guys,

I'm looking for advice as how to proceed from a major mistake. The first thing I did with my new wing spars was mis-drill the tie down extrusion on the upper surface of the L spar. (I got cocky after the 1st 3 and drilled & tapped with the spar positioned such that extrusion was underneath the spar where I couldn't see everything that I was doing. Learn from my mistake!)

The image is a bit blurred, but you can see that the drill was angled toward the surface the extrusion and has surfaced. For the photo, I re-inserted the tap and you can see it in the surface.

So far, I have identified 3 paths to pursue. Easiest (and therefore of greatest suspicion) is to ignore it and use the tie down as if nothing happened. The threads are intact along the upper (as oriented in the photo) and lateral walls of the long axial hole, but probably non-existent on the lower edge of the hole directly under the unwanted opening. As a total WAG, I guess that there's a 30? arc x 1/2" where there are no threads. Is that lack of contact enough to compromise the strength of that bolt? (What is the function of that bolt, anyway? I'm further guessing that it's to suspend the wing in maintenance actions.)

2nd option is to ignore it completely. That is to say mark the tie-down as InOp and never use it.

3rd option is to re-drill with a larger bit and re-tap with larger threads. To ensure good strength, I would tap 2" to obtain a full inch (original spec) of completely engaged threads. Will there be sufficient aluminum to accept the larger bolt?

Any and all inputs on how to proceed are certainly welcome!


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  #2  
Old 11-07-2013, 05:54 AM
rgmwa rgmwa is online now
 
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If its on the upper surface of the spar, you can ignore it. The tiedown ring will screw into the other end, on the lower surface of the spar.
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  #3  
Old 11-07-2013, 07:19 AM
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Ron RV8 Ron RV8 is offline
 
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If the piece is symmetrical end to end you could reverse it. If it's not, for the price and effort I would replace it. I think most of us end up with a couple of unusable parts. Drill and start the tap in a drill press if you can before attaching it to the spar.
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  #4  
Old 11-07-2013, 08:30 AM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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I'd replace it on ethical grounds.

Here's why. Proper tiedowns are as much about protecting the planes near you as they are protecting your own plane.

Drilling out the rivets won't take long and the part is cheap.
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  #5  
Old 11-07-2013, 08:37 AM
David Paule David Paule is offline
 
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And if you do replace it, Cleaveland or Avery tools sells a pre-threaded one at a fair price.

Dave
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  #6  
Old 11-07-2013, 09:01 AM
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I sent you a PM
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  #7  
Old 11-07-2013, 09:05 AM
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XOverZero XOverZero is offline
 
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I would want to replace it, but since this is an RV-12, the associated issue becomes one of re-setting those 3/16" rivets. Unless you have a heavy duty pneumatic squeezer and experience with this larger rivet size, you may want to shop locally for professional help. In any case, a quick note to the Mothership would be appropriate before diving into the spar.
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  #8  
Old 11-07-2013, 09:23 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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As already mentioned... Is this the one for the top of the spar or the bottom.
If it is for the top, I would just move on. It is very unlikely it will ever be used for any purpose that would apply a high pull load.
If it the bottom position, I would replace it.
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  #9  
Old 11-07-2013, 09:37 AM
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I have an extra from my RV-8 kit. Make an offer.

Don
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  #10  
Old 11-07-2013, 10:25 AM
YellowJacket RV9 YellowJacket RV9 is offline
 
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I went through a few tie-down extrusions after mis-drilling them to the spar on my 9. I would replace, and ask Van's about the option of replacing those 3/16 rivets with bolts if you can't find somebody handy to re-rivet. It would probably be an acceptable repair, as I believe it is bolted on all the other models.

Chris
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