Need Help repairing strut

[KewFlyer]

I bumped the bottom of the right wing strut (long story how I did it... ). The A&P IA agrees that needs to be repaired.

The question to the tribe is: is it legal ( FAA 4313) to use 4130 steel say 35th or 40th to cover the area [top and bottom] overlapping and following the same shape of the strut and weld all sides to the strut ?
Any other method to do the repair?
Thanks to all for the advice
Ralph

[Pearson]

Re: Need Help repairing strut

Ralph,

Before the wing strut AD came out, my plane had several splices on the struts. They might as well have been painted flourecent pink for as much as they stood out. It was the one thing I really hated about my plane. Now that I have new sealed struts, I don't have to live with that anymore.

The reason I hated having those splices was because of the poor welding job someone did when making the repairs. It looked like a one eyed, intoxicated, dirt dauber did the welding.

My point is, if you are going to repair your struts, make sure the welds look really nice because they will be the focal point of your airplane when anyone walks up to it.

With that said, my suggestion would be to search around and try to find a strut, or a pair of struts, to just replace yours. With all the struts that have been replaced in the last couple of years due to the AD, there is bound to be a replacement laying around somewhere. Obviously you would want to have it checked out first. But if you could find a nice clean strut it would save you the trouble of doing the repair, and you wouldn't have an obvious patch for everyone to comment on when they walk up to your plane.

If you do decide to do the repair, AC43.13 has a good picture with a table of metal thicknesses to use. In my old copy dated Sept 1998 it is on page 4-74.

Good luck!

[KewFlyer]

Re: Need Help repairing strut

Richard:

Thank you for your advice.
The A&P IA is looking for a 3 3/4" x say 10" piece of steamline strut to be sliced open on the back side and slide over the strut to serve as a sleeve, and then welded it on. First option was to get it from Spruce [4130 streamline] , but the one they sell is not of the same size.... others have suggested to get a piece of 4130 and mold it to the strut as it is welded on.... and the easy solution is to get a new one or a certified/to be certified used one.

Any suggestions, advice comments, etc... are welcome

Thanks in advance

Ralph

[Hank Jarrett]

Re: Need Help repairing strut

If you can't get a used strut I would go for a new one. You will always hate the look of a repaired strut every time you walk up to the plane, plus you will still have to do the recurring inspection.
I have only seen one strut repair that looked good. We found the repair when we were blasting the strut to repaint it. Chunks of Bondo came out of the middle of the strut. It had been repaired by driving a chunk of wood into the two halves and butt welding the pieces together. They then dented in the welds to grip the wood and Bondoed the joint. It was beautiful to look at and you couldn't tell it had ever been repaired. That plane had flown for DECADES like that with no sign there was a problem. NO, there was NO doubler!
I think the two halves ended up in a homebuilt landing gear. It was hard as H**L to pull apart! These struts have a HUGE structural safety margin. We trash them because the rules say we have to, not because they will fail in use. I wish we could have convinced the FAA to let us proof load them instead of failing them from inspection.
I have another friend who taxied a tandem Taylorcraft into a hidden hole and bent his struts on one side when the gear failed. He wrapped control cable around the lugs on each end and 1,000mph taped a piece of wood to the broken strut to keep it straight. He then flew home with it like that. I couldn't convince him to not try it, so I just got his "Next of Kin" phone number and the track home he planned to fly. He made it fine, but I would NEVER Let a friend do it again! Scared me to death! Fools and small children.
Hank

Just replace the strut.

[Guest]

Re: Need Help repairing strut

Richard:

Thank you for your advice.
The A&P IA is looking for a 3 3/4" x say 10" piece of steamline strut to be sliced open on the back side and slide over the strut to serve as a sleeve, and then welded it on. First option was to get it from Spruce [4130 streamline] , but the one they sell is not of the same size.... others have suggested to get a piece of 4130 and mold it to the strut as it is welded on.... and the easy solution is to get a new one or a certified/to be certified used one.

Any suggestions, advice comments, etc... are welcome

Thanks in advance

Ralph

Hi Ralph,

I repaired mine by getting a piece of 3.372" x 1.429" streamline from Wicks. It will slide over the original strut but is a tight fit.

You may prefer to slice the trailing edge to trim and fold in place. I did not, I was ok with a slight mismatch rather than welding the TE and I had a method of sliding into place even with the snug fit.

link to Wicks Page=> http://www.wicksaircraft.com/catalog...345/index.html

10" is way too short, better re-figure that, min. length is over 18" and then you have to add the width of the damage.

I suspect that those suggesting "molding" may have never done it. That's the only way it could be attractive in my opinion. I don't recall 43.13 permitting that. But it will be much neater to buy a slightly bigger tube and trim the TE to fit as I suggested.

Ralph get hold of a current copy of 43.13-1b with updates and read the section on strut repair. There are approved methods. Get an update version because the original version has the wrong min. length in the table.


I have lot of used tube. What are the exact dimensions?

Dave

[Arnold Wallace]

Re: Need Help repairing strut

This reminds me of a dented Continental "oil sump" once repaired by bolting a plate onto the large attach hole, screwing one of those expanding automotive soft plugs into the filler neck, and then applying about 40 psi of air pressure (regulated). A fine heat pattern from a torch warmed the metal in a circular pattern and the dent slowly pushed out to the original shape. Of course the metal needed to be cleaned, etched, primed and painted to make it a repair good enough for your white glove inspection.
Disclaimer - Not to be preformed by anyone not familiar with oxy-acet welding or those in a rush. If memory is correct, this was an all day job.
Perhaps the above mentioned strut could be salvaged safely with a comparable application of heat and air pressure?
N96175

[Rex Havis]

Re: Need Help repairing strut

I have replaced my struts with new ones. It Appears that I have three good struts and one that questionable. If you are intrested and will let me know which one you need, I'll check to see if its one of the good ones. I'll sell at a good price. Rex

[mulwyk]

Re: Need Help repairing strut

I sent you a private message about the struts, Rex.