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Tiedown: small rings


George in San Diego

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As a new LS owner with a hangar, I haven't had to tie it down until recently. It seems these tiny rings were designed for small diameter rope and not for chains which are standard at CA airports I frequent. So far nothing fits except snap hooks on the end of a chain. Links themselves will not go through the hook as they will on my C-150. Are there larger rings available or any other ideas? Snap hooks are rare and unless there is a 2nd hook mid-chain to take up slack, even a standard hook at the end won't work since the links can't be pulled through. Surprised by such a basic ground handling issue.

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If you can find a carabiner that is strong enough and the right shape, that will work.

If not, you can get a chain link with screw closure and a larger ring that will pass the tie-down chain. You won't want to leave either of these ideas mounted permanently, just connect them on the ground as needed. You could get a chain hoist hook (the kind with the spring closure so the hook won't slide off the ring) and put a large chain link on that. Lots of ideas if you don't want or care about replacing the ones that are there.

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It is very common, but I've never had a problem with it. The chain won't fit through the hole, but you just have to adapt to the problem. Use the S hook to go through a link in the chain at the right length and then hook the S into the CT tiedown ring. I've never had it come out

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It is very common, but I've never had a problem with it. The chain won't fit through the hole, but you just have to adapt to the problem. Use the S hook to go through a link in the chain at the right length and then hook the S into the CT tiedown ring. I've never had it come out

 

It's interesting to hear that an S hook works, as my experience on the farm with an S hook is not so sanguine. Do you know it's load carrying capacity? It's an elegant idea if one is comfortable that it will do the job.

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Just get a real, rated carabiner from a sporting goods shop, online or otherwise.

 

We use cheapies for all sorts of things, but the one I'm looking at now says on one side "NOT FOR CLIMBING" and on the other side "SAFE WORKING LOAD 150 LBS". Probably do NOT want to use one like that.

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It's interesting to hear that an S hook works, as my experience on the farm with an S hook is not so sanguine. Do you know it's load carrying capacity? It's an elegant idea if one is comfortable that it will do the job.

I meant the S-hook that is already attached to the end of the tiedown chain. I don't carry anything to use with the chains.

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400 lbs should be enough under most circumstances, but...

 

A quick Google search can up with this recommendation for CAP aircraft:

 

b. Tie-Down Ropes and Straps. Tie-down ropes and straps with tensile strength of 3,000 pounds or greater shall be used. Nylon or Dacron tie-down ropes are recommended. When specified tie-downs are not available, crew members shall use ropes/straps appropriate for anticipated environmental conditions.

 

Remember, with the right wind, your wings can generate in excess of 1,320 lbs. of lift. And it's probably not as simple as just dividing that by 3.

 

FWIW, I carry three motorcycle tiedown straps and use those. I have no tiedown rings so I use "Soft-Ties" around my struts and hook to those, with another wrapped around the nosewheel - the way my plane is balanced a tail tiedown would just pull down the tail, leaving the nose in the air with the wings at a big angle.

 

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A quick Google search can up with this recommendation for CAP aircraft:

 

b. Tie-Down Ropes and Straps. Tie-down ropes and straps with tensile strength of 3,000 pounds or greater shall be used.

This is right out of the 1983 edition of AC 2-35C Tie Down Sense. It is for all single engine aircraft, which includes Bonanza, Cherokee 6, Cessna 210, and even bigger.

To be honest, I doubt if we need that much strength.

Some time ago, I asked FD what the load rating was on the tie-down ring and never got an answer. It doesn't make much sense to use a tie-down system that is very much stronger than the tie-down rings (of course, the loadings could be different - I'm not being flippant here).

I looked around the internet and didn't find much of help. The Claw claims it is good for 1200 lbs per unit, if I recall, so it makes little sense to get a rope stronger than that (above caveat applies).

Aviation Consumer discusses tie downs but only in the anchor part, not much on the ropes.

One does get some tips like you need a little springiness (chains are bad) but not slack (promotes hitting the device harder) and says that knots are weaker than rope (which we all know anyway). There is nothing wrong with reading the AC, it just seems like it might be overkill.

In the end, it may come down to personal bias, personal ignorance, personal laziness, personal zeal.....you name it - not much definitive science that is readily available and is applicable to LSA.

 

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This topic may be overly technical already, but I'll throw another log on the fire...

To avoid the aircraft "wanting to fly" while on the ground, I've seen Lift Spoilers used. These are nothing more than something put on/over the wing to spoil the aerodynamics of the wing. It can be something as simple as flimsy netting. In Alaska, they have wing covers that serve two purposes, keeping frost/snow off the wings, and spoiling any lift. With a lift spoiler in place, the strength of the tie downs is less important (but still something to consider).

I've thought of using something like this to help in special situations, like on dirt strips in Mexico, where the tie-downs are flimsy or non-existent.

Tim

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I recall that thread. No answer from FD but I doubt those rings could take more than a few hundred punds of pull which is really plenty. No slack is very important as the impulse force from a jerk is many times higher than the static loading. If you ever do have to tie down in advance of a hurricane, then the most important thing to do is make sure the stick is held neutral or a bit forward. I jam my seat cushion in. The CT will generate 1400lbs of lift in 50MPH wind (650lbs net) but only if the tail goes down so the AOA is large. Think of it this way; how fast would you have to go to take off with the stick held slightly forward? Maybe 150kts

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This has all been very interesting and makes me realize I live in an area where we simply don't have experience with REALLY bad weather. A little tour of our local SoCal airports will show that the chains are almost always slack and a close up look will show S hooks on nearly all of them. Some or most S hooks are not nearly as strong as the link chains they are attached to and would probably just straighten out and let the airplane tumble away in a serious wind. We don't get big hail, nor do we get big winds. Indeed some just let their planes sit unattached. The Bizet FBOs often don't have tiedowns at all. But this would never be wise for the CT and other lightweights. For myself, the issue of tying down will apply only when I'm away from home base and I think if I were expecting serious weather somewhere on a long vacation trip I'd plan ahead to get into a hangar if at all possible.

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