Struts

[Dick Smith]

Re: Struts

Dan, you might investigate "Splash Zone"...look into this site:

http://www.epoxyproducts.com/under4u.html

It's been used here in Alaska on metal boats for a long time...I've used it on Alum. floats...amazing substance. Dick

[Mark Julicher]

Re: Struts

Here is a thought.

Perhaps the end of the strut could be sealed with a caulking agent more permanent than silicone but less aggressive than epoxy. The strut could then be drilled/wired with a .060 stainless wire with a crimp-on lead witness tag. The logs could require the tag to be in place for the struts to be airworthy.

[Dan Michaels]

Re: Struts

Thanks guys,

What I have found so far as the most acceptable to the FAA, Neely Industries. They make epoxy for aircraft airframes used specifically to seal. In all types including pressurized and jet fuel applications.

West coast epoxy is also something they should know about.

I have two sets of ends now, (One coming) If anyone knows of any more, only the two upper ends and only 6" or so. I would like to apply any epoxies I find that have a high chance of approval.

I think I found a way to seal everything in steel it will just cost more and be a little harder.

Dan

[VictorBravo]

Re: Struts

What about this idea:

Cut the lower 12 inches of the strut off of the main strut. The lower 12 inches is the part that everyone is worried about.

Turn it upside down and bang it on the table and see how much rust and flakes come out. ( While you're in there, see if W's weapons of mass destruction are there. See if Jimmy Hoffa is in there. See if Amelia Earhart is in there, or the single aerobatic magic bullet that killed JFK, did a loop and then hit Connolly's hand is in there. See if you can find Obama's US birth certificate or his college records while you're at it. You might have to look behind the formula for the secret Nazi synthetic fuel to see all this stuff. )

Sandblast the inside of the lower 12 inch piece thoroughly. Easy enough access now that it is a separate piece.

By visual inspection with a normal length borescope or strong light and inspection mirrors, verify that the now-bare and exposed metal has not been significantly eaten away by corrosion. If it becomes necessary, measure the wall thickness with some sort of a caliper or mike.

Look up into the upper section of the strut with the borescope and see if there is any serious corrosion there either.

Apply some kind of epoxy or Par-Al-Ketone or whatever anti-corrosion coating would be correct.

Using an INTERNAL sleeve, several good rosette welds and correctly chamfered edges on the strut pieces, weld the strut back together. Grind it all flush and smooth if it is desired. Through the last hole, dump in more corrosion proof stuff to coat the sleeve repair, then weld up that hole.

Do a field-test where the strut is pull tested using a simple large hydraulic jack, verifying the strut can take a 6G pull (something like 4 or 5 thousand pounds on one front strut I'm guessing, the engineers can figure out the geometry and minimum pull number easily enough)

Repaint and reinstall strut.

This should all still be a little less than the cost of new struts. Why?
1) Because the owner can do a significant part of it at no cost if he needs to save money. (remove strut, cut strut, collect rust material sample from inside strut, sandblast strut end... and then grind/file/paint the repaired strut afterwards)
2) A qualified T-craft forum member with the right equipment could set up a production line to do it efficiently.
3) Univair or an established repair station can also set up to do it very easily
4) No specific PRECISION welding jigs are needed.
5) The internal sleeve can be made out of flat steel strip if needed, and bent over a wooden form.
6) A fairly simple fulcrum and lever device can be made to apply a 5000 (whatever) pound pull force on the strut using a Harbor Freight hydraulic bottle jack, a surplus I-beam section and a couple of steel plate scraps from a construction site. Even a poorly educated chimpanzee such as myself can design and figure out the leverage and fulcrum dimensions to apply such a force from a cheap jack...

[Dan Michaels]

Re: Struts

The strut I took apart had been welded together almost the same way other than they used the AC 43.13-1B as approved method. You do not want to grind off the weld to make it smooth. They also put the patch on the outside as it shows in the Circular.

A better way will be to just put some steel shot down the tube and vibrate it around then dump it out. I also have some Silica gel that I can put in to remove any moisture. I think I will then use the SS epoxy primer on it inside and out.

Dan