Need an Opinion on Damaged Airframe

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kopanskin

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Good day,

I have acquired an EAA Biplane that I'm trying to get back in the air (no rush) and I removed the leg rests to find a bent tube from the accident. The accident happened on the taxi ramp from a drunk driver running his truck into a wing by "accident" (previous owner). NTSB report explains in further detail. I literally have no experience building/maintaining an aircraft and I planned on becoming more knowledgeable through this project. I have glanced at the publication from the FAA for structural building, but it really isnt quite clear and thats where I have some questions on the process.
Do I need to cut this tube/ re-bend what I can/ then weld a larger diameter tube over the existing (after cuts are made) to reinforce it? Just looking for some opinions on what everybody else would do in this situation.
Thanks!
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Armilite

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It's an Experimental, isn't it? Your the repairman. If it was me, I would cut it out and replace it. In your last photo, look where the Tubes towards the bottom meet, it looks like you may have a Rust/Crack issue there also. It is possible to strighten and put a piece of Tube inside the tube and reweld it up to strenghten it also. I would use a 4"-5" piece inside. Do you know the Tube Spec's?
 

BJC

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It's an Experimental, isn't it? Your the repairman. If it was me, I would cut it out and replace it. In your last photo, look where the Tubes towards the bottom meet, it looks like you may have a Rust/Crack issue there also. It is possible to strighten and put a piece of Tube inside the tube and reweld it up to strenghten it also. I would use a 4"-5" piece inside. Do you know the Tube Spec's?
The OP is not a repairman, in the FAA definition of one authorized to perform an annual condition inspection.

I would replace the tube. For it to have kinked that way, there must be some deformation of one or both longerons. Take a good look at the entire structure, and get a second opinion from your local EAA chapter Technical Counselor.


BJC
 

TFF

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Cut it out and throw it away. Way easier. Repairs of tubing is when you can't cut it out as the easy way. You need to set the fuselage up and really look hard at how straight it is. Chraftsmanship vs accident. Little tweaks in tubes or longerons get fixed. Totally whacked needs to go.
 

Turd Ferguson

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The FAA publication, AC 43.13-1B provides acceptable methods and techniques for repair. They are not the only methods. Should not be a problem to cut the weld, straighten the diagonal, install a sleeve over the damaged tube then reweld the cluster, as you (and AC 43.13) suggest. Will be a lot of torch work and time consuming. Being relatively uncomplicated, I'd just replace both of the tubes with new - cleaner, lighter repair. Did you remove the missing fabric stringer? Is the other stringer (bottom of pic) broken as well?

Doubtful that is isolated damage, in fact it looks like compression damage so there had to be a lot of flexing going on during impact and I can't imagine the longeron(s) is(are) still straight. Ensure the entire section of the fuselage is carefully inspected.
 

THRC12

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Would be something we could fix easily and check out the rest of the structure as well. Not sure how far Goose Creek is from Lincolnton, NC though. Teddy
 

Winginit

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Good day,

I have acquired an EAA Biplane that I'm trying to get back in the air (no rush) and I removed the leg rests to find a bent tube from the accident. The accident happened on the taxi ramp from a drunk driver running his truck into a wing by "accident" (previous owner). NTSB report explains in further detail. I literally have no experience building/maintaining an aircraft and I planned on becoming more knowledgeable through this project. I have glanced at the publication from the FAA for structural building, but it really isnt quite clear and thats where I have some questions on the process.
Do I need to cut this tube/ re-bend what I can/ then weld a larger diameter tube over the existing (after cuts are made) to reinforce it? Just looking for some opinions on what everybody else would do in this situation.




Thanks!
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After studying the pictures, I'm not sure what you have here. Are you sure that the tube kinked and isn't just some kind of poorly made joint right from the original build? I say that because nothing else appears to be out of whack. Usually a joint is the strongest part of the assembly, and you would expect the tube to bow before the joint deformed. As I mentioned, the pictures aren't as clear as seeing it first hand. If it was originally made that way and just cracked, it could be cleaned and rewelded and
maybe a little gussting added. If it was jamed due to an accident, I would expect there would be other parts showing some deformation, but there really doesn't appear to be any. If it is bent from the accident, it may be stressing other parts. I would just cut off/out maybe a 1/2 inch from the deformation and weld a sleeve back in place. Make a larger diameter sleeve about 4 " long and split it in half longways. Shape it for best fit around the irregular V-butt and weld it in place. Having said that, you also need to verify that you don't have misalignment or warping elsewhere before you start the repair. If you get into trying to replace the whole tube, it may become much more difficult because of the other items that may have to be cut loose and then trying to reweld them without sufficient room to position the torch, and things like nearby cables and fuel lines. I would stick with trying to limit the repair to as small an area as possible. If the whole thing NEEDS replacement, then do that. If on the other hand only the affected area needs repair, don't create other difficulties by expanding the repair area.

Question? In photo #2, is the hump just above the crack a deformation or an old weld ?
 
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Turd Ferguson

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After studying the pictures, I'm not sure what you have here. Are you sure that the tube kinked and isn't just some kind of poorly made joint right from the original build? I say that because nothing else appears to be out of whack.
The plane was hit by a truck while it sat on a ramp. The kinked tube is due to compression overload, transmitted from the point of impact through the wing spar and longeron. Repairing the obvious damage is only part of the equation, need thorough inspection to ensure there is not other damage that may not yet be discovered. I would not want to do a lot of work and find out during assembly and rigging that something is so far out of whack it has to be torn back down.
 

proppastie

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whole tube from one side of plane to other on the diagonal needs to be replaced one way or the other... say cut 6" from each side slide fish-mouthed tube over stubs and weld, might have to fish-mouth an added piece to the tube meeting at the center if it is not long enough after cutting.
 

Winginit

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The plane was hit by a truck while it sat on a ramp. The kinked tube is due to compression overload, transmitted from the point of impact through the wing spar and longeron. Repairing the obvious damage is only part of the equation, need thorough inspection to ensure there is not other damage that may not yet be discovered. I would not want to do a lot of work and find out during assembly and rigging that something is so far out of whack it has to be torn back down.
Yes, I agree that he needs to inspect for other damage before doing the repair. From looking at the pictures furnished, I see some questionable conclusions and asked for more information. I'm not sure the original diagonal tube was perfectly straight to begin with or cobbled together at that point. I don't see how that joint could have suffered impact and nothing around it appears to be disturbed. The larger tube at the front where the straight tube connects doesn't appear to be bent. Others may see it more clearly than I do, but from what I can see, I can't be sure. So I asked for a little more information from the OP. Could it be a poorly formed joint that cracked from vibration or stress and was discovered after the accident, or is an actual defect caused by the accident. From the picture, I can't tell. The thing is that if the accident caused this, shouldn't other damage also be apparent ? The wing spar and longeron are not directly attached to this point, so it would seem things between those two items should also be showing the results of compression. Without more information I don't know.
If it proves out that the only damage or problem is at this joint site, then I see no need to expand the repair any further than a simple repair at the affected site. It will be as strong if not stronger than the original. Expanding the area by replacing the whole tube may disturb other unrelated components and create additional problems. Ultimately it is up to the OP to decide how big a project this will become.
 

Turd Ferguson

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The thing is that if the accident caused this, shouldn't other damage also be apparent ?
What do you think happened to the stringer that is broken off about 7" in front of the former under the seat? What about the right side stringer (bottom of picture), it appears to be broken as well right under the diagonal (probably a tab that attaches the stringer to the fuse there...). I doubt it was installed that way.

So there is "other damage," for all I know it could have occurred when during subsequent moving of the airplane. Without specific knowledge, I would strip it down, inspect, repair as needed (and make sure I was happy with the seating position) then build it back up. Big job but when done it will be a neat plane.
 

Winginit

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What do you think happened to the stringer that is broken off about 7" in front of the former under the seat? What about the right side stringer (bottom of picture), it appears to be broken as well right under the diagonal (probably a tab that attaches the stringer to the fuse there...). I doubt it was installed that way.

So there is "other damage," for all I know it could have occurred when during subsequent moving of the airplane. Without specific knowledge, I would strip it down, inspect, repair as needed (and make sure I was happy with the seating position) then build it back up. Big job but when done it will be a neat plane.
What I'm alluding to is that since the location of the damage is under the seat, its possible that some hard landings had an impact in this area prior to the accident. I'm only speculating based on limited ability to analyze the furnished photos. I'm just not jumping to a conclusion, but rather trying to insure that all possibilities are considered. Usually if a component inside other components suffers a bending compressing moment from an outside source, the main members supporting that component will show some displacement. The stringer is wooden and could have been broken at any time given its location under the seat. I'm not saying thats what occurred, only speculating that there are other possibilities and need a little more info from the OP and maybe some more pictures of the surrounding infrastructure. I'd like to see some pictures of the external impact location too.
 

kopanskin

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Thanks for all of the replies!
I have uploaded more pictures after taking a better look at the from the damage. I have marked each photo with a number (#) to better reference. In one of the pictures you can see a little boy, that's my son/helper lol.
It looks like there is more damage than originally thought (bummer). The lower left wing is the wing that was struck, and the wing is definitely damaged (will upload those pics in a few hrs). It looks like he hit the leading edge corner, by the wing tip, in which pushed the wing into the side of the fuselage. I'm already prepared to rebuild the wing, if it is salvageable...
I have a friend who welds for a living and says he could do the welding, and teach me at the same time.
I took some time last night to see if the tube along the fuselage was bent going towards the emphenage, and it only looks bent beside the pilots seat along the left side. One thing I'm concerned about currently is the eyelet mount that the lower wings bolts to (the mount closest to tail section). I haven't pulled back the covering to inspect it further, but will do so.
Ive tried getting a hold of my local EAA chapter but have received no reply. I'm guessing it isn't that active. I will reach out to the next one 30 miles away soon to see if I can get a hold of them. A person to come asses the damage would be very helpful and hopefully they have one.
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kopanskin

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Ill make sure he is up to par first before I let him start welding on my airplane lol. Me and him go way back in the USMC and he went to school for welding, so hopefully he can do it. Ill have him practice on some test pieces first to make sure he can handle it. Any tips you know of, that I should tell him about?
 

BJC

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Rockiedog2

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what does the bushing in pics 8 and 9 do?...with the cracks. that took a real load
 
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Rockiedog2

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it doesn't look used but of course I can't really tell from the pics. I'm wondering why it's cracked like that. it looks like the wall of the bushing is cracked longitudeionally... I haven't seen that before
 
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