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Tie down rings on or off.

Art_N412SB

Art_N412SB

Member
Hi all,
During preflight do you remove your tie-down eyelet's? Check the POH under Right Wing and Left Wing preflight. In both areas the POH says Tie-Down - REMOVE eyelet. I am thinking that the POH is trying to say, "don't install the eyelet's until you need them". Funny, it does not say the same thing for the tail tie down eyelet.
I have heard it explained that there is a possibility of dissimilar metal corrosion if you leave the tie down eyelets installed in the wing. What do you do about this and why?
Thanks
 
Art_N412SB said:
I have heard it explained that there is a possibility of dissimilar metal corrosion if you leave the tie down eyelets installed in the wing. What do you do about this and why?
Thanks
Click to expand...

I have never heard that, but if it had shown it self to be a problem, there are lots of bolts and screws that would be a concern as well.

It is best to leave the tail tie down ring permanently installed because it acts as a tail skin if you ever accidentally drag the tail (just grinds a little bit of cheap steel instead of a lot of expensive parts.

As for removing the wing tie downs...... That is how you achieve the spec'ed max. cruise speed of 120 Kts. If you leave them in, the speeds in the POH wont match ;)
 
Mine Retract

My RV friends gave me a hard time for leaving the wing tiedowns on our RV-6, and I didn't like the location of the left one because the tiedown rope/chain got hung up on the pitot tube. Besides, they're a bit awkward to reach. So I made up a set of spring loaded ones that attach to the spar and wingtip ribs. Fixed!
 
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I consider the wing eyelets optional. We don't need them in the hangar, but if parked near helicopters or jet blast while inside the restaurant at temporary tie downs visiting other airports for "$100 burgers", they get installed and chained up to the tie down cables, and removed again, before take off. A clean, aerodynamic plane is a happy, efficient flying plane per gallon of fuel burned.

The rear eyelet makes a good taildragger substitute instead of grinding the aluminum skins back there in the event of an "oops" moment.
 
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tie down eyebolts

As several others mentioned, I leave the tail tiedown eyebolt installed permanently so that I have a tail skid. A very experienced CFI told me years ago that if you never bump the tail GENTLY on the runway then you are not making full stall landings. After nearly 400 landings on my RV-12 that seems to not be the case, but I am still watching for it. I have a hanger so the wing eyebolts are in the glove box but have never been put in place. When I occasionally tie down outside I put the ropes thru the wingtip hand holds. Seems to work fine.
 
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There when you need 'em

The thing about tie-downs is that when you will need them, it will likely be raining, windy or some other ugly weather and then you'll be standing there with the canopy open looking for where you had them stowed (assuming you carried them with you). They have insignificant drag on the airframe and are downright handy when needed, so I leave them in all the time.

I did buy the stainless powder coated ones from Cleaveland Tools and install them with antiseize, so corrosion shouldn't really be an issue.

I do swap them out at annual to install lifting jack points, and then reinstall with fresh antiseize.
 
In a moment of anxious weight shedding efforts, I bought a pair of expensive titanium eye-bolts and ground them down to the right length/shape. They stay on the airplane. I suppose I could have achieved the same gross weight reduction by switching to light beer for a while......
 
mr.sun said:
I suppose I could have achieved the same gross weight reduction by switching to light beer for a while......
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That?s a good observation. I?m sitting around on snowy Saturday morning, so I searched the average American man 20 years old and up weighs 197.9 pounds and average waist circumference is 40.2 inches. Looks like human evolution is progressing faster than I thought. If you?re looking for increased performance and fixated on aircraft empty weight, you?re probably working on the wrong problem...
 
Folding tie down rings

Can someone please make folding tie downs for our RVs? An aerodynamic blister or fairing shape with a center bolt and a fold down ring. Google folding tie downs or folding race hooks and there are lots of ideas. The ones below are just rough ideas.

folding-race-hook-screw-type-porsche-3.gif
HTB1HsW5n_nI8KJjSszgq6A8ApXaE.jpg_q50.jpg
 
One thing about leaving them out: mud daubers! At least in Florida where I'm located.

Had a heck of a time getting one screwed in when I needed it. I don't carry a 3/8-24 tab (or whatever the thread is) with me. :(

Perhaps I should look into a plastic plug of some sort.

Finn
 
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Charlie12 said:
When I occasionally tie down outside I put the ropes thru the wingtip hand holds. Seems to work fine.
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Probably would work fine in winds wheret the only concern is about the airplane getting turned/moved slightly, but in instances where weather is severe and you really hope to keep a light airplane like an RV-12 from flying out of it's tie down spot, I would not recommend using the lifting handles on the wing tips.

They are not designed to take anywhere near the loads that the threaded tie down anchor can.
 
One of the reasons to remove them is the potential issue with dissimilar corrosion; steel threads in an aluminum fixture.

For that reason, I do not leave them in when flying.
 
corrosion

The potential for corrosion is ALWAYS there unless the two metals are the same. Looking at the galvanic corrosion charts, Cad plated steel is generally not an issue with aluminum. Stainless can be an issue, as it is further from aluminum on the chart and Titanium is even further. Using aluminum rings would be bad due to the lack of comparable strength and the tendency for aluminum on aluminum tends to gall very easily. Using stela's or even stainless with a light grease or anti seize is probably the best balance between strength and potential corrosion issues...
 
plastic plugs

In line with Finn's reminder about mud daubers, I searched around online and did manage to find white plastic push-in cap plugs that fit the tiedown holes and protrude very little on the outside. I bought several spares but the originals have stayed in place for 3 1/2 years.

I agree with the recommendation that it would be unwise to use wingtip lift handles to tie down in strong wind. I taught structural design for 30+ years and the relative strength observation makes perfect sense. With an airplane as light as an LSA I don't do anything in strong wind.
 
Standard Tie Downs work

rvbuilder2002 said:
Probably would work fine in winds wheret the only concern is about the airplane getting turned/moved slightly, but in instances where weather is severe and you really hope to keep a light airplane like an RV-12 from flying out of it's tie down spot, I would not recommend using the lifting handles on the wing tips.

They are not designed to take anywhere near the loads that the threaded tie down anchor can.
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Agree with Scott, on one of the trips to Oshkosh 3 of us stopped in Dayton to visit the Museum, we got a call that next morning from the FBO stating there were 3 RVs trying to fly away. The good news the tie-downs worked despite the heavy winds and damage around the area

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Note the damage at the Wright Brothers Historical site that morning.

All three of us had the standard tie downs :)
 
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Old thread, but I just finished making these So i thought I'd share. 170 layers of fiberglass and alot of sanding later. Zero area perpendicular to the wind and plenty strong. I just don't like the idea of constant removal and installation. That's how threads get wrecked
 

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Moosedude said:
Old thread, but I just finished making these So i thought I'd share. 170 layers of fiberglass and alot of sanding later. Zero area perpendicular to the wind and plenty strong. I just don't like the idea of constant removal and installation. That's how threads get wrecked
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Like this.... :cool:

Is the whole structure fiberglass, or do you have an underlying metal ring?
 
On my -9A, the previous owner put some Cleveland tie-downs on and faired all three with some clever 3-D printed covers he bought here on VAF. I'm sure they're very aerodynamic, but that that stuff apparently can't be painted, so they're kind of a bone white against my yellow paint. I can't see 'em from the cockpit, so I'm OK with that and just left them, although I did pull the one on the tail and replaced it with a big steel ring so I can mount a GoPro, and have something to bounce off the concrete runway, just in case...
 
emsvitil said:
Like this.... :cool:

Is the whole structure fiberglass, or do you have an underlying metal ring?
Click to expand...

They are solid fiberglass. I basically made a little wooden box about 8 by 2 by 2, brushed some resin, then stacked pre cut 6 inch lengths of glass in 4 at a time, then tamped them in with more resin. Rinse and repeat until 170 layers was in. Work fast in a cold room and only use a minimum of MEKP to slow the reaction. Then I took another piece of wood the same as the bottom piece but an inch shorter than the box and pressed it in with 3 big c-clamps. I measured before hand to know where that piece would be to achieve full compression. All the excess resin ran to the ends of the box and left the glass fully compressed to cure over night. The end result is just as strong as aluminum and could be even stronger if you used carbon fiber.

Oh and all the wood was wrapped in heavy plastic.
 
MacCool said:
On my -9A, the previous owner put some Cleveland tie-downs on and faired all three with some clever 3-D printed covers he bought here on VAF. I'm sure they're very aerodynamic, but that that stuff apparently can't be painted, so they're kind of a bone white against my yellow paint. I can't see 'em from the cockpit, so I'm OK with that and just left them, although I did pull the one on the tail and replaced it with a big steel ring so I can mount a GoPro, and have something to bounce off the concrete runway, just in case...
Click to expand...

Mine are going on a 7a. Still have to make another one for the tail. I think I've seen those 3d printed ones somewhere and thought they looked pretty darn good. But I don't have a 3d printer, but I do have a ton of fiberglass and resin laying around
 
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