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Old 11-07-2013, 05:15 AM
dbhill916's Avatar
dbhill916 dbhill916 is offline
Join Date: May 2013
Location: Westerville, OH
Posts: 171
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!

David B. Hill
RV-12 #0760
Dues paid through 6-2022
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Old 11-07-2013, 05:54 AM
rgmwa rgmwa is online now
Join Date: Feb 2010
Location: Perth, Western Australia
Posts: 1,675

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.
RV-12LR 912ULS
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Old 11-07-2013, 07:19 AM
Ron RV8's Avatar
Ron RV8 Ron RV8 is offline
Join Date: Nov 2010
Location: Okanagan Valley BC, Canada
Posts: 500

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.
Ron Townson
Okanagan Valley BC, Canada
RV-8 Completed Dec 2013

Membership renewed Nov 22, 2021
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Old 11-07-2013, 08:30 AM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
Join Date: Jan 2005
Location: St. Paul, MN.
Posts: 4,826

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.
Bob Collins
St. Paul, MN.
Blog: Letters From Flyover Country
RV-12iS Powerplant kit
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Old 11-07-2013, 08:37 AM
David Paule David Paule is offline
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,063

And if you do replace it, Cleaveland or Avery tools sells a pre-threaded one at a fair price.

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Old 11-07-2013, 09:01 AM
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Fearless Fearless is offline
Join Date: Aug 2006
Location: Crestwood, KY
Posts: 848

I sent you a PM
RV-9A Based K6I2
Flying - out of Phase 1
Building RV-12 with brother
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Old 11-07-2013, 09:05 AM
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XOverZero XOverZero is offline
Join Date: Aug 2010
Location: Irvine, CA
Posts: 427

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.
John Halcrow
Tustin, CA
RV-12 120682
Emp/TC done; Wings done; Fuse kit done

"Keep flying. Malcolm Reynolds
Paid up until Aug 2022
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Old 11-07-2013, 09:23 AM
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rvbuilder2002 rvbuilder2002 is offline
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,660

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.
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Hubbard, Oregon
Van's Aircraft Engineering Prototype Shop Manager
RV-6A (aka "Junkyard Special ")
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Old 11-07-2013, 09:37 AM
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cfiidon cfiidon is offline
Join Date: Apr 2008
Location: Arizona
Posts: 657

I have an extra from my RV-8 kit. Make an offer.

RV-8 QB Titan ECi 191HP XIO-360
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"Pilots are alchemists... we turn gold into lead."
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Old 11-07-2013, 10:25 AM
YellowJacket RV9 YellowJacket RV9 is offline
Join Date: Oct 2012
Location: Clearwater, FL KCLW
Posts: 1,330

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 Johnson
RV-9A - Done(ish) 4/5/16! Flying 4/7/16
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