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Wing tie down ring problem

Michael Burbidge

Michael Burbidge

Well Known Member
It appears that the tie down ring is tightened by bottoming it out on the bottom of the threads rather than snugging up against the skin. There is about a 3/8 inch gap between the skin and the tie down bar. If the ring doesn't bottom against the threads before reaching the skin, then it will deform the skin. I apparently tapped the tie down bar a couple of threads too deep because the ring reaches the skin before reaching the bottom of the threads.

Has anyone had this problem? How did you fix it?

Thanks,
Michael-
 
I dont have the same problem [too deep threads] , but like the idea of the tie down bottoming on a base. I thought of opening up the hole and then bonding a spacer/washer to the solid aluminium bellow the skin.
I feel if you are jacking the plane up using wing jacks, it would be better to weight the base instead of the threads in the hole.
But then again Im probably overthinking the whole issue as usual ?

To easily solve your issue, Get or make tie down rings with longer threads.
To make, buy some long stainless bolts and get someone to weld a ring to the hex head. Then shorten the bolt to an agreeable length.
 
Just put some tank sealant (or similar) around the first few rows of threads adjacent to the eye so that you can't screw the tie-down ring in all the way. If you really want to be industrious, you could fabricate some sort of bushing to cover a few rows of the threads giving you a stop.
 
Had the same problem. If you want to get anal about it, just go to your local hardware store and get an allen head plug. Run it up in there. Problem solved and it keeps bugs out when your tie-down rings are not in place.
 
If the tie down rings are to be installed only as required, you really don't have much of a problem. Simply run the rings in till they barely touch the skin, then tie the plane down. If, however, you plan to fly the plane with the tie-rings routinely attached, Jamie's idea seems a rather simple, elegant solution.
 
Just curious, do most of you take the rings out when you fly?

I too like the plug idea, I've used that method before on my kit car I built. Only additional suggestion is to use some loc-tite on the plug. I never thought it would vibrate out, either that or someone is running around with an allen wrench taking plugs out for some amusement.
 
Interesting, I never thought of the tie downs as "removeable". Guess it's easy enough to toss them in the back for when you fly places.

Thanks.
 
I had the same problem, I fly with mine in.

solution I came up with was to thread a nut all the way onto the ring before installing it into the bracket. Used as a jam nut you can then position the ring where you desire and tighten it down.

You may have to oversize the hole in the bottom wing skin just enough to allow the nut to recess thru it. works for me.

doug
 
seldom used

My 9A is hangared so I only install the rings when I have to tie down the plane at another airport.

Steve
 
Jamie said:
Had the same problem. If you want to get anal about it, just go to your local hardware store and get an allen head plug. Run it up in there. Problem solved and it keeps bugs out when your tie-down rings are not in place.
Click to expand...

I made the same mistake, and am planning to go the same route ^^ as Jamie to solve it.
 
Interesting...

Mine were bottoming out on structural elements in the wing. All I did was grind a few threads off the ring, now they snug up nicely.

Hans
 
If you have any problems with keeping them oriented the way you want them, get some faucet washers from the hardware store and use one of the right size to cushion at the base. It will hold it from turning when you fly, but it does not have to be torqued up tight.

Randy C
 
When Van designed the -8, he gave us a subtle clue that he doesn't think they should be installed while flying....he designed in storage points in the baggage compartment to put the rings! I think it's mostly an appearance thing - mine only go in on the rare occasions I am tying down outside.

Paul
 
Do y'all cover the tie down hole?

Jamie, your plug idea is a great way to make the tie ring bottom out. What value is that if the rings are stored most of the time?

And do you plug\cap the hole on the wing or just ignore it?
 
Great info...

Great information. Thanks for all the responses. I think I'll use the plug and not put them in when flying. It never crossed my mind that they shouldn't be permanently installed.
 
Tie-down ring 'problem'

oh, to have such problems....you 'hangar' queens kill me!
........but I wonder..............
If I go to a fly-in at the next field, leave my aircraft on the ramp while I do the wine tour thing, and come back to find a windstorm has put it on it's back......I don't think it's worth the dime to call the insurance company!
I'll be leaving my ugly, draggy rings in, and look for decent tie-downs when I park.

(maybe when I have more than 14 hours on it.... I'll worry less!)
 
dougknight said:
I had the same problem, I fly with mine in.

solution I came up with was to thread a nut all the way onto the ring before installing it into the bracket. Used as a jam nut you can then position the ring where you desire and tighten it down.

You may have to oversize the hole in the bottom wing skin just enough to allow the nut to recess thru it. works for me.

doug
Click to expand...

This is what I did - I ran a jam nut up onto the ring into the correct position, then silver-soldered it in place. Life is good.
 
dhall_polo said:
Jamie, your plug idea is a great way to make the tie ring bottom out. What value is that if the rings are stored most of the time?

And do you plug\cap the hole on the wing or just ignore it?
Click to expand...

The only value I really saw was maybe helping to keep bugs out of the wing and to prevent the ring from being tightened to the point that it scratches the paint. Honestly, that's about it. It's just that I was in the hardware store one day looking for something else and I saw the plugs and thought to myself, "hey, that looks like a decent idea". They were $0.10/ea so I figured it was worth a try.
 
I had the same problem. I found two slightly undersize spacers that were a force fit over the threads and installed them. They keep the eye just off the skin. And yes, I hangar mine and keep them removed in threaded storage holes in the baggage compartment. A simple matter th unscrew them and install in wings for tie down purposes.
 
flyboy1963 said:
oh, to have such problems....you 'hangar' queens kill me!
........but I wonder..............
If I go to a fly-in at the next field, leave my aircraft on the ramp while I do the wine tour thing, and come back to find a windstorm has put it on it's back......I don't think it's worth the dime to call the insurance company!
I'll be leaving my ugly, draggy rings in, and look for decent tie-downs when I park.

(maybe when I have more than 14 hours on it.... I'll worry less!)
Click to expand...

After 450 hrs. on my -7A, I take the precaution to make sure it's tied down wherever I land. I frequently fly 400 - 500 nm and stay 2 - 3 days. After hassling with screwing them in and out and losing a couple in the process, the time saved by the knot or 2 speed savings was eaten up by the extra time spent with them on the ground. They are now securely installed in the tie down holes.

By the way, WW Grainger has the same tie down rings for 1/2 the price of the various RV vendors.
 
Using nylon spacers to fill the tie down bracket/skin gap

Here is what I'm planning on doing prior to installing the leading edges on the wing spar.

http://www.overthehills.com/RV-9A-Project/Wings/Leading-Edges/11060344_qcwa8#774205099_bn3Bs-M-LB

http://www.overthehills.com/RV-9A-Project/Wings/Leading-Edges/11060344_qcwa8#774205299_f7FpK-M-LB

http://www.overthehills.com/RV-9A-Project/Wings/Leading-Edges/11060344_qcwa8#774205449_aes8a-M-LB

With these spacers in place, I should be able to tighten the eye bolt down enough, and not squish the skin, or just leave them out if they are not needed.
 
Spacers and small rings

I "glued" small aluminium spacers between the skin and the brackets with RTV, so that the skin will not get "squished".

When the plane is painted, I will use plastic or rubber rings to avoid damaging the paint and to be able to tighten the rings in the right direction. A little Lock-tite will make sure they will not fall out during flight.

The rings I use, were tig welded at work (stainless steel bolt and a small plate, than drilled and finished on a grinder). These rings are so small (3/8 hole) and so light, that they can stay in all the time (Will I loose 0,05 knots X 3 = 0,15 knots top speed ?? :confused::D). I will use the very light weight carabiners, that mountain climbers use, to attach the ropes. The rings are probably stronger than the threads in the aluminium wing bracket.


f_ui4s0gu4m_bf39317.jpg


Regards, Tonny.
 
New Tie down ring

Shameless plug here. JD air has a new tie down ring in the works that is intended to stay on the plane. It will be streamlined like a small fin. When the tie down is needed you pull on the spring loaded front (or back) to expose the opening for the chains.

Problem solved. A cool system that you don't have take on and off.
 
Ok, I've been meaning to wait until painting, but here is my solution to the tiedown ring issue. (note to Bob Axsom, this gave me 2.735 knots extra speed:D)

Made from a piece of scrap 1/2-inch Al and some threaded rod. Before final installation I will replace the threaded rod with a hardened steel threaded rod. Threaded rod will be epoxied into the Al block, and I will use an o-ring around the shaft to keep from rubbing the bottom wing skin, and help hold the tiedown in the proper orientation.



Top view, showing lightening holes.



Side view. The little plug fits into the hole and is held by friction on the o-ring.



Cheers,
greg
 
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