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Oiling Fuselage Tubes

Also I think the Stitts oil is supposed to seal up any pinholes in the weld.
 
TrentF said:
Also I think the Stitts oil is supposed to seal up any pinholes in the weld.

Haven't been that lucky. Find slight pinholes in 60 year old factory frames. There are self plugging 1/8" rivets for this purpose. Coat the inside and then drain the excess. Makes a real mess when you start covering if it finds a way out.
 
Corrosion proofing inside the tubes?

What do the cub kits do about corrosion proofing in the tubes? None of the websites talk about it. I bring it up because a friend has had corrosion issues in the lower longerons of a Cub clone, where the floorboards attach.

So I guess there are two questions here: Is corrosion a real problem in modern Cubs which, like my friend’s, have never been on floats, never landed on a sandbar, and never been within 500 miles of salt water? And what do the kit manufacturers do to prevent corrosion, particularly inside the tubes?

I don’t really want to get into details of his problem, as it isn’t my story to tell. This was just a Christmas party conversation. For all I know it’s total fiction. YMMV and other disclaimers........
 
What do the cub kits do about corrosion proofing in the tubes? None of the websites talk about it. I bring it up because a friend has had corrosion issues in the lower longerons of a Cub clone, where the floorboards attach.

So I guess there are two questions here: Is corrosion a real problem in modern Cubs which, like my friend’s, have never been on floats, never landed on a sandbar, and never been within 500 miles of salt water? And what do the kit manufacturers do to prevent corrosion, particularly inside the tubes?

I don’t really want to get into details of his problem, as it isn’t my story to tell. This was just a Christmas party conversation. For all I know it’s total fiction. YMMV and other disclaimers........

StuBon, I merged several old threads on the same subject. Wicks and Spruce has the closed end rivets and tube oil.

http://aircraftproducts.wicksaircraft.com/item/all-categories/blind-rivet/ad41h

http://www.aircraftspruce.com/catalog/cspages/ad-41hclosedendpoprivet.php?clickkey=43840
 
What do the cub kits do about corrosion proofing in the tubes? None of the websites talk about it. I bring it up because a friend has had corrosion issues in the lower longerons of a Cub clone, where the floorboards attach.

So I guess there are two questions here: Is corrosion a real problem in modern Cubs which, like my friend’s, have never been on floats, never landed on a sandbar, and never been within 500 miles of salt water? And what do the kit manufacturers do to prevent corrosion, particularly inside the tubes?

I don’t really want to get into details of his problem, as it isn’t my story to tell. This was just a Christmas party conversation. For all I know it’s total fiction. YMMV and other disclaimers........

I've bought two brand new airframes in the past 10 years, one certified, one experimental, and neither had tube oil added. The comment I've heard is that this new chromoly tubing is pretty oily when the airframes are put together so there's already an oil coating in there. I can't speak to the benefits or waste of time of adding more oil but I didn't add any.

Your friend's floor should attach to tabs welded to the tubes. He shouldn't have any perforations in the tubes themselves. I don't understand the description of lower longeron corrosion from attaching the floor. Certainly not internal corrosion.
 
Stubob

I guess the question would be......was the corrosion from the inside out, or from the outside in? Was the corrosion - where the floor boards are- caused by the floorboards, ie from the outside? That is the source of 90% (a guess) of most issues. It would be pretty rare for it to be from the inside out unless water got trapped in the tube some how. I hope I'm communicating this. I think the vast majority of corrosion/rust issues are from the outside - not inside.

Bill
 
Having repaired a lot of fuselage the only time I have seen internal corrosion was when there was a crack or hole in the tube somewhere allowing moisture or humid air in. See way more external corrosion from dirt and debris on the outside of the tubing. When I cut into my 1949 Clipper fuselage because of external pitting the inside of the tubes were still oily.
 
Your friend's floor should attach to tabs welded to the tubes. He shouldn't have any perforations in the tubes themselves. I don't understand the description of lower longeron corrosion from attaching the floor. Certainly not internal corrosion.
At least one popular kit attaches the floorboards with screws into the tubes rather than tabs. I didn’t think to ask about outside-in vs inside-out.
 
only put oil in one fuselage at rebuild, welded fill holes shut... but it still found spots to leak out when it was in the powder coat oven... the powder coating guy was not impressed by the mess and smell in his fuselage oven...

put it in another after it got sunk

rest have been dry
 
I hate to ask, but that is so egregious, are you sure that is per the kit manufacturer and not just what this builder did? Sometimes builders are pretty inexperienced and will do goofy stuff (like me) but if that is truly the way the kit is built......holy cow....thats bad.

Bill
 
It’s an S-LSA, so the factory drilled the holes.

The consensus seems to be that I shouldn’t expect the tubes to be corrosion-proofed inside, and the floorboards should be secured to tabs or glued on or something that doesn’t involve holes in the tubes. Is that about right?
 
It’s an S-LSA, so the factory drilled the holes.

The consensus seems to be that I shouldn’t expect the tubes to be corrosion-proofed inside, and the floorboards should be secured to tabs or glued on or something that doesn’t involve holes in the tubes. Is that about right?


clarify please, drilled in the LONGERONS? or just cross tubes?? begging for cracks...
 
When I was building my Cub I had a junction we found that hadn't been welded closed yet. So as a precaution I put some crawling oil in. Boy was I sorry. I later I drilled a couple of very small holes in the tube just behind the sliding window for the trim to pin the rest of the trim in. I had long ago quit thinking about my corrosion worries. Long story short.. I later started covering the fuse, the oil very slowly but seeped down the tube and into the C window channel as I started to rotate the fuse. The cleaning dog fight was on. I finally overcame it after several days of repeat cleaning. Should've listen completely to the advice Bill gave me in the first place. I hope posting these mistake will help somebody else not make the same. Merry Christmas Friends!
 
When I was building my Cub I had a junction we found that hadn't been welded closed yet. So as a precaution I put some crawling oil in. Boy was I sorry. I later I drilled a couple of very small holes in the tube just behind the sliding window for the trim to pin the rest of the trim in. I had long ago quit thinking about my corrosion worries. Long story short.. I later started covering the fuse, the oil very slowly but seeped down the tube and into the C window channel as I started to rotate the fuse. The cleaning dog fight was on. I finally overcame it after several days of repeat cleaning. Should've listen completely to the advice Bill gave me in the first place. I hope posting these mistake will help somebody else not make the same. Merry Christmas Friends!

Would Corrosion-X have been better?
 
Personally I would not bother oiling tubes for several reasons.

1) Factory production aircraft don't do it and if they did, they would mention it and probably list a surcharge due to the extra p.i.a factor

2) as mentioned above. coating/ painting issues.. Not worth the hassle
3) Again Hassle, added labor and time. besides most of the "stories about the benefits are somewhat anecdotal, Just like the when we heard of Mig welding airframes were verboten as they would crack. There was this story some years back of some airframes of a future Lsa that had been Mig welded and fell apart from massive cracking. There was no evidence, just a story. As we know now, there are many manufactures that use the simple Mig welding process to stick their fuselages together with NO post treatment and they survive just fine.
4) You'll probably be too old to care, or dead by the time, if any it becomes an issue.

If your building ,make sure a competent welder does the job, and his welds are consistent in all positions and If your still concerned, slop on some extra fabric glue over the welds as you cover. no reason to make a mountain out of a mole hill.
 
Air Tractor drills a hole at every cluster with a bung at the firewall. They pressurize the fuselage with hot linseed oil and then after it cools they drain the excess out. The welders have to go back and fix any pin holes that show up.

Don't drill holes in tubes. Piper drilled the U channels not the tubes for interior trim and door welting along with the D window trim on right side. The last two Super Cubs I have rebuilt (1979 and 1982) had the holes drilled in the middle of the tube instead of the edge of the U channel. I think Piper was lossing their experienced help.
 
adding tube seal ??

About what size hole do you drill in the tubing to add oil to the tubing?
What do you do to seal that hole?
Thanks
 
Seal the hole with a closed end pop rivet. Drill the hole to match. 1/8” or so works
 
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  1. I usually avoid oiling tubes.... only had one owner demand it...
  2. If you are going to have it powder coated, you must wait till after baking ... or it will piss out, or deform things(like lift struts turn back into semi round tube if you don't drill a hole and drain them and leave them vented(sealed newer struts)
  3. did I mention i hate oiling tubes ;-)
 
Well, I oiled my longerons. Drilled 1/8 inch hole, put the amount per instructions on the Poly Fiber Tube Seal can. I used pop rivets dipped in JB weld with another layer of JB weld over the head of the rivet to seal. haven't seen a drop of oil anywhere WHEEeeeeewwww !!! :) Thanks for the input.
 
Why oil if the parts are sealed properly? I did that to my PA-11 but by then whatever decades old corrosion present had already happened. Pressurize the tubing and seal the air leaks would be my next fix.

Gary
 
I've scrounged tubing from derelict fuselages which have been left outside in the salt air for years. The only places where I've found any rust was near where there was an opening or break in the tube. All the rest was still like new inside. Even the outside was still good. That old zinc chromate did a good job. Conclusion, if you can keep the tubing sealed, it will remain in good condition.
 
A question might be: Are fuselages typically open somewhere or sealed? If open where would we look for leaks to seal if that can be done?

Gary
 
Older J3 fuselages have holes drilled in the bottom of the lower longerons just forward of the tail post, later ones don't. Everything else I have seen is sealed up unless someone drilled a hole somewhere for some unknown reason. Super Cubs have 3 screws into the door tube to hold the interior panel under the door. I weld these up on a rebuild and weld attach tabs there. Also on the 79 thru 82 model Super Cubs I have worked on Piper drilled into the tubes around the door frame to install the welting to seal the door where on earlier models this holes were only drilled into the U channel that is stitch welded to the door frame tubes. Haven't seen an issue as of yet but I have welded the holes up and drilled the U channel on the ones I have recovered.
 
Thanks Steve for your post on fuselage openings. My PA-11 had two drilled as you describe and we sealed them.

Another question: Where are the typical spots subject to external corrosion and eventual holes? I was told one was at the rear left window area. Of course longerons but maybe there's some common spots to examine.

Gary
 
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