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Jury Strut Eye Bolts


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Hi All,

 

Looks like I need to replace the Jury Strut eye bolts on my SB Drifter. One fractured through whilst flying on Saturday. Looks like stainless steel, tried a bolt supplies shop today without any luck. Looked on line tonight but couldn't find anything to match.

 

Any ideas where to find 8 of these little eye bolts. Here's a couple of pics.

 

image.jpg.a93d41c3d68832c58614b38ae7873b51.jpg

 

image.jpg.249b091c760687c8ef72543873072095.jpg

 

 

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Purely as an observation on the 2nd pic, I would prefer to see one of the jury struts the other side of the cleat to minimize bending of the bolt.

 

Bruce

 

 

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Don't buy anything for this application from a bolt supply shop. The quality of the metal has no control and is likely to be either soft and bend or be brittle and break. Aircraft grade metal is the only thing you should be considering.

 

 

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Except the original part is actually SS and was taken from use of boat turnbuckles.

 

I searched far and wide for these myself and could not find them the next best thing is eye bolts alluded too by OME.

 

 

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Guest SrPilot
Looks like I need to replace the Jury Strut eye bolts on my SB Drifter. One fractured through whilst flying on Saturday. Looks like stainless steel, tried a bolt supplies shop today without any luck. Looked on line tonight but couldn't find anything to match.

BJFly, for the FWIW department: Over the years as friends and I were building some airplanes we followed advice from some of the old-timers - we avoided the use of stainless steel in any structural application - bolts, nuts, tubing, etc. We were always told that stainless was or would become brittle, and was subject to failure under shear. Whether true or not, I know not. [i am not, and never have been an engineer - I went straight for a business degree - rather than going to an engineering school which we called “a pre-commerce curriculum.” (Many aspiring engineers ended up with us in commerce. We just took the shorter route.) You may be an engineer and know more about this stuff than I do, but I've only had a few in-flight failures - thankfully not of catastrophic degree, and I seek no more.

 

I note the suggestion that some of the hardware on the airplane may be stainless and at least one bolt broke. Ergo, my old rule of thumb comes into play for me - if it failed once, why tempt fate? It may fail again and at a time not of one’s choosing. (Similar to my physician’s advice when I showed early signs of a hernia - fix it now.You don’t want that thing to wrap around something important while you’re inbound for crosswind landing in a taildragger.” Sounded like sound advice to me, so they fixed it in one-day surgery; I ended up with two punctures and a little screen implant. Now I can go looking for a crosswind while in a taildragger. Or not.) 059_whistling.gif.a3aa33bf4e30705b1ad8038eaab5a8f6.gif

 

Anyway, I’d suggest reading up on stainless before choosing it for structural components such as bolts, and I’d surely follow the suggestion to use only aviation grade components. If it's not AN grade, it doesn't work for me in structural applications.

 

Here’s a brief discussion of stainless steel that might prove interesting at least to whet the appetite. 062_book.gif.f66253742d25e17391c5980536af74da.gif

 

http://machinedesign.com/materials/comparing-stainless-steel-and-other-metals

 

Meanwhile, fly safe.

 

 

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I agree with SrPilot about the use of stainless steel for fasteners that are subjected to high stress and strain loads. CRES (Corrosion Resistant) fasteners are really only good for holding non-structural things like panels and upholstery. Use the AN eyebolts because are made from the same steel as bolts, nuts and washers. If you are concerned about corrosion, and it looks like you've got it, then dab some paint on the fasteners after they have been fitted.

 

I also agree that it wold be a good idea to balance the forces on that strut bracket by putting the eyebolts on either side.

 

And again ... If you look at the AN style eyebolts you will see that the end (where the bolts which fastens it to the strut bracket go through) is flat, giving you a larger contact area between the head of the bolt and the eyebolt, thereby allowing the compression forces to be spread over a larger area.

 

http://www.aircraftspruce.com/catalog/hapages/eyeboltsan44.php?clickkey=26589

 

BUT HOLD ON!!!!!

 

I just had another look at the original eyebolts. They don't have much in the way of unthreaded length (called grip length). The AN style eyebolts are designed to go through a structure, such as a trailing edge spar. They as fitted with a washer and nut on the back side of the spar, so they have a lot of unthreaded length.

 

If you use the AN eyebolt, you are going to have to measure how long a Grip you can get away with before the eyebolt becomes thread-bound. Wind an AN bolt into the nut on the jury strut and then bring the strut into position with the bracket, and measure the distance between the bracket and the start of the thread on the bolt. This will give you a Grip Length value that you can use to select the correct AN eyebolt.

 

OME

 

 

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Thanks all for your guidance. I have looked at the catalogue OME advised. Unfortunately can't seem to find an Eye bolt that has the same dimensions. I can find a match on some of the dimensions, but not all. Being a mechanical numpty it is possible I'm missing something.

 

If anyone has recently replaced theirs and has a part number guidance would be appreciated.

 

Here's a pic with some measurements. I hope I'm using the correct terminology.image.jpg.0c79f84dd2f806b5a465e4f792c9193a.jpg

 

 

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Hi All,Looks like I need to replace the Jury Strut eye bolts on my SB Drifter. One fractured through whilst flying on Saturday.

Looking at your photos, I`m not surprised it broke!!! Why did you let it get to that state and continue to fly?.... Not good!!!

 

Frank.

 

 

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As mentioned by TEX, the (broken) part you have, was the single eye end of a stainless steel boating turnbuckle, typical hardware for early ultralights.

 

What you should be replacing with is a cad plated steel turnbuckle pin eye, as opposed to a cable eye, which has a bigger hole.

 

If you have a 10/32 (3/16th) thread, and a 3/16th hole for the joining bolt, you would be looking for an AN165-16RL.

 

If you enter this number into the Aircraft Spruce website, the image you get looks like the stainless steel version.

 

If ordering, try by phone, and just check you are getting the cad plated version.

 

Have a look here; http://spenceraircraft.com/ms21254-3rl-turnbuckle-eye-end-for-pin-clip-locking-10-32-right-long-alt-an165-16rl.html

 

Not cheap unfortunately.

 

AN165-16RL.jpg.99f7f9504b3207f01ddbb8a4c3276ec3.jpg

 

There is a shorter version, which would be an, AN165-16RS.

 

 

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Just to clarify the Part Numbering.

 

AN165 is now MS21254 (Same dog, different collar)

 

-16 is the minimum breaking strength in pounds (Not used now)

 

R indicates a right hand thread. If you are screwing these Clevis Ends into a normal nut, or threaded hole, you would use a right hand thread. When used in a turnbuckle situation you would have one of these on each end of the turnbuckle, one with a right hand thread and the other with a left hand thread.

 

S & L indicate the distance between the centre of the through hole and the end of the shank/beginning of thread. In the AN 165, the S and L were always the same (S = 1-1/8", L = 2"), but under the MS system the lengths increase as the Clevis End gets thicker.

 

PLEASE NOTE:

 

Although the LEGAL measurement system used in Australia is the Metric system, aircraft hardware described using one of the AN, MS or NAS systems is IMPERIAL (based on the inch in 1/32" sub-units). In practical terms, unless you are working on aircraft components made in Europe, you always measure in Imperial. So, get yourself a 6" rule graduated in 1/16" for measuring the length of parts, and a Vernier caliper that measures in 1000ths of an inch. Here's a conversion chart: https://www.specialtauto.com/delorean-parts/images/inch-to-metric.jpg

 

OME

 

 

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This is a Ronstan yacht fitting

 

The part number from the AustFlight SB Drifter parts catalogue is "RF P/N734", They called it a "Rigging Screw"

 

The Ronstan website does not list this part anymore, But an Eye end bolt from a Closed body turnbuckle Rf218 looks the part

 

If you ring them I'm sure that they could help you,BUT tell them its for an off-road vehicle!

 

This is a low loaded part, And the dissimilar metal corrosion problem can be fixed with anti-seize or low strength loctite on the threads

 

Hope that this helps, We need to keep our drifters flying

 

Shane

 

37231-c2ef4c90e77219879372b82c6e082c06.jpg

 

RF218.jpg.513878cdf1164c6f04a52966f8368e3c.jpg

 

 

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Once again thanks for the info. Whilst picking up replacement AN bolts/washers/nuts the good folk at Maryborough Aviation Services confirmed the part number and ordered them. Once I know it fits correctly I'll post the part number/supplier/cost.

 

 

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strutfit.jpg.f2774c04516f4c066a039e3f30cfb898.jpg

 

Just as a point of interest, the only strut here that is really going to do anything is the vertical one, during (heavy?) landings.

 

As such, it should be up against the riveted tang, and then the horizontal strut.

 

As shown above, the vertical strut has a bit of leverage at bending/breaking the bolt.

 

I also think that only a thin, if any, washer should be put between the tang and the eye fitting, keeping the shear as close as possible.

 

Just my 2¢ as an L2...

 

 

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  • 4 weeks later...

Hi All,

 

Finally replaced all my eye bolts on the Jury struts.Here's what I discovered over the last couple of weeks.

 

Despite getting a GA workshop to order replacement parts, there doesn't appear to be an exact match in AN bolts. The bolts in the picture below were tried however as OME alluded too, the unthreaded length and the overall length did not match. To get this to work you would have to re-sleeve all the struts.

 

Next was the turnbuckle solution mentioned by Shane. I think this would work but be prepared to pay upwards of $100 for each turnbuckle(you can't just buy the eye end)

 

Another solution was to re-tap the inserts in the struts with a 6mm thread and fit a 6mm marine grade eye bolt(easily purchased).

 

I guess the Last option is to beg / borrow / scrounge some original parts from someone's dead or dying Drifter.image.jpg.ef81da73596374d1eab4791031c5d6b7.jpg

 

 

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