Strut Cuffs

[Hank Jarrett]

Re: Strut Cuffs

On the strut tie down question, if you have the loops on your struts they are NOT used to tie the plane down! Most of them are cast aluminum and will NOT hold your plane (I need to dig up the pictures I have of a plane on it's back with the tie down ropes still tied to the broken rings).
The ring is to keep the ropes from sliding down the strut, they DO NOT take the tie down load!
Run the rope up and through the ring, then around the strut and back through the ring and tie it off. The load goes into the top of the strut, NOT THE RING. The ring should be located as high on the strut as you can put it and still have enough strut exposed to tie the rope to. If the rope slides down the strut it WILL bend the strut. The cuffs will have no effect on the tie down if you set it up right. Note that the CUB style wire rings attach to the wing spar fittings and I don't think you can use the cuffs if you have that type ring (I also don't think those type rings are even legal on a Taylorcraft, they are Piper parts). I have a set of the Piper, heavy wire rings (actually a loop that attaches to the strut top bolt) and they fit and work fine, but I couldn't find them in any of the Taylorcraft parts books.
Be careful how you tie your plane down. It takes very little wind to break those rings if you tie to them wrong.
Hank

[senior]

Re: Strut Cuffs

On the strut tie down question, if you have the loops on your struts they are NOT used to tie the plane down!

That's my understanding too.
I have a set of Strut Rings with Taylorcraft marked on the box, but they don't fit the struts right so haven't got around to customizeing them on.
My other question was if you install cuffs would that lower your tie-down point on the Strut enough to worry about bending one

[Hank Jarrett]

Re: Strut Cuffs

I think (no calculations, just experience) that if you are within 8" or 10" of the top attach you aren't going to hurt the strut. The two critical loads on a strut are tension and long column buckling. You design for both and take the largest. On a wing strut long column buckling dominates. Without the jury struts they would have to be HUGE! The jury strut effectively cuts the strut length in half. long column still dominates, but it is closer to being even with tension (at least it is within 10 times).
That was the problem with the strut inspection. Corrosion at the bottom reduced net section, which reduced the tension strength, but the strength was already SO HIGH to handle the bending loads in the MIDDLE of the strut that you could have actual HOLES in the strut from the corrosion and they wouldn't fail! That was the the point I kept trying to make to the FAA. They had a pile of "failed" struts that had been laying in the mud and had corroded through on one side, but they didn't have ANY struts that had actually FAILED through the corroded section! FAILURE of the strut would require that they have one that was IN TWO PIECES. IF they are in one piece, they didn't "fail" in service, they were destroyed in STORAGE! We could have safe struts by doing a simple punch test on the bottom side of the bottom end. If the punch goes through REPLACE THE STRUT, even though it still has enough section to take flight loads.
I never could get them to understand they are rejecting struts for corrosion that is actually just cosmetic! If we clean up the corrosion, protect the surface inside, seal the strut and PROOF LOAD IT to a load well beyond the flight load, THE CORROSION PITS DON'T MATTER! There is plenty of residual strength in the strut.
If anyone has rejected struts, please DON'T trash them. I will use them for landing gear struts and cabanes and interplane struts on a homebuilt! Of course I will clean them up, coat them and proof test them, but there is NOTHING wrong with the material if you inspect and treat it.

Sorry, rant over. Just REALLY makes me mad when engineers with lots of letters after their names make decisions about things a REAL engineer who has been in the field has the answer to and they won't listen. We have lots of good people in the FAA but some of their leadership has lost touch with the real world and won't do the analysis to find the right answer. They would rather just play it safe and make us eat the cost of replacements that aren't needed.
And YES, I DID inspect my struts by their directions AND my way. I didn't trust their way to find real problems. But then, I'm anal. ;-)
Hank

[Forrest Barber]

Re: Strut Cuffs

How true , we load tested here at a fly-in and even I was surprised at what a corroded strut could still with stand.

"Monumentous decisions are not always made by monumentous people" !

[Larry Lyons]

Re: Strut Cuffs

Can you see them now??
Sometimes computors amaze me
I can see the photos.
I copied & pasted them again, exactely the same as before.

I must be the only one that doesn't see them. Not to worry, I have plenty of resources around here. Thanks, Larry