Corrosion Treating the Inside of the Cabanes and Diagonals

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Terry Hand
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Joined: Thu May 18, 2017 2:37 pm

Corrosion Treating the Inside of the Cabanes and Diagonals

Post by Terry Hand » Wed Jan 17, 2018 8:39 am

I have built my cabanes and diagonals, and I chose to use 4130 Chromoly streamlined tubing as opposed to aluminum or wood. I want to corrosion treat the inside of the cabanes and am looking for suggestions. Steve D, I know you mentioned using CorrosionX on your Bonanza. Which version? How would you apply to the inside of the tubes?

Thanks in advance for the suggestions.
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Semper Fi,

Terry Hand
Athens GA

tom kreiner
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Joined: Sat Feb 25, 2017 9:49 am

Re: Corrosion Treating the Inside of the Cabanes and Diagonals

Post by tom kreiner » Wed Jan 17, 2018 5:36 pm

Terry,

The recommended way to address internal corrosion of the tubing is to make sure the ends are sealed, after which small holes will be drilled. Near boiling hot Linseed oil is then pumped into the chamber within, and is "sloshed" throughout. The holes are subsequently plugged with small screws.

This is described in 43.13 Sec. 6, par. 6-42

JamesR
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Joined: Wed Jan 17, 2018 5:32 pm

Re: Corrosion Treating the Inside of the Cabanes and Diagonals

Post by JamesR » Wed Jan 17, 2018 7:02 pm

Some type of galvanization or metal electro plating would provide corrosion protection in all the hard to reach places.

Steve D
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Location: Grand Republic of Texas

Re: Corrosion Treating the Inside of the Cabanes and Diagonals

Post by Steve D » Wed Jan 17, 2018 7:37 pm

Here is what I did on my steel cut down piper cub struts:

I stripped and derusted the outside. (I found wrapping them in aluminum foil while coated with stripper worked best. followed by steel wool.
Then rustoleum self etching primer and White Rustoleum auto paint (rattlecan)

Then I Then put a tiny light inside one end and took a look. Some rust but nothing bad. This plane was kept indoors.

Then I plugged one end (with the threaded attachment)
Bought Boiled Linseed oil (($19 per gallon, I would have preferred raw as it does not harden, but boiled is good also.)
Heated the linseed oil up (in a big pot of water on a outdoor propane burner) to about 150F
Used a funnel and hose to pour it inside each strut. (I put in way more than needed, but it is cheap)
Plugged the holes with my gloved fingers and Rolled the struts all over the axis for about 5 minutes each. You could hear it slosh.
Poured most out, but left some in and leaned them in the corner waiting to go to the airport.

I will "reslosh" before I put them on.

I put the extra back in the gallon can, so now I have 7/8ths of a gallon left. Too bad it cannot be used with Latex paint.

I decided not to do the AD required for a Piper cub. Using a Maule Fabric tester on it for 2 reasons, 1. It beats up a $300 dollar Maule fabric tester and 2. It beats up your strut. This test is where you put graph paper on the bottom end of the strut and punch the strut in each square, thin wall dents. My IA buddy really doesn't like this test. I bought a ultrasonic metal thickness tester and used that. My IA later traded me out of it.

Why linseed oil and not the newer oils? I looked at CorrosionX, LPS, ACF50 and several other products. None seemed to do much more than what the Linseed oil would do. It flows in well and (especially heated, like a thin oil) fills all the little crevices and seals holes. Then it hardens, first as it cools and then more as it ages, to a waxy oxygen barrier. (Raw stays more waxy, Boiled eventually gets hard.) So no more rust production without O2. I can retreat about 8 times, Cheap and predictable results.

That was several years ago. I still have Linseed oil slowly seeping out. BTW If you get linseed oil on your old suburban upholstery It will not come out for love or money!

On most items, If I think I see corrosion somewhere I tend to spray with Corrosion X aviation (Stops corrosion dead), and sometimes follow with LPS 3 (Waxy and water resistant.)

Blue Skies, Steve D

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taildrags
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Re: Corrosion Treating the Inside of the Cabanes and Diagonals

Post by taildrags » Thu Jan 18, 2018 11:14 pm

FWIW, epoxy will generally not adhere to anything with wax in it. Just sayin' in case you think about getting the linseed oil near anything you're going to try to epoxy. Also a reminder that if you're going to lay up fiberglass or epoxy something with threads in it that you don't want to have clogged with epoxy, rather than trying to carefully fidget around the part you don't want to glue shut, just take a candle and melt a bit of wax down into the threads before you do your layup or brush on thinned epoxy (as onto a wood frame before covering). Once the epoxy cures, you can dig out the wax with a dental pick or toothpick and then run a screw into the threads and it's clear.

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