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Bent elevator spar

jcarne

Well Known Member
Patron
Updated/fixed? Bent elevator spar

Good day gents, in my infinite dumb-assery I managed to accidentally bent my elevator spar flange a bit. I have an email into Van's on this one but I was wondering what you guys thought on whether I should replace the spar or just bend it back into place. It looks to me that the top flange is bent but I don't believe the main web of the spar is bent, the bottom flange also looks as though it didn't really get bent either. Thanks!

2i7y9om.jpg

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A good opportunity to "counter-flute"! Counter-fluting may not be the best method but that looks like a quick and simple fix.
 
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I'd try to bend it back into place, but unless you can get rid of any, and I mean any out-of-planeness, the spar probably should be replaced. Or it can perhaps be doubled there by adding a doubler.

Either way, this is a critical structural issue and you should contact Van's support.

The aspect that makes it important is that when the spar cap is loaded in bending, the flange is in compression and any deviation from straightness is a potential location for local buckling. Local buckling of a spar cap is a failure mode.

Dave
RV-3B, now on the fuselage
 
Looks fixable from photo

From the photo it looks like it could be bent back into position without issue. However as others have mentioned, get feedback from Vans.
 
Spar

I'd try to bend it back into place, but unless you can get rid of any, and I mean any out-of-planeness, the spar probably should be replaced. Or it can perhaps be doubled there by adding a doubler.

Either way, this is a critical structural issue and you should contact Van's support.

The aspect that makes it important is that when th spar cap is loaded in bending, the flange is in compression and any deviation from straightness is a potential location for local buckling. Local buckling of a spar cap is a failure mode.

Dave
RV-3B, now on the fuselage

I wouldn't even consider it. Replace it. It's not installed yet so a swap is easy.
 
Thanks for the replies guys, I'm pretty keen on replacing it myself even though I'm torqued about it. I don't mind paying the $20 bucks to Van's it's the $31 dollars to UPS that I'm not happy about. This will be the third time I will have to ship a spar and it's getting old, I wish my mistakes were on tiny doublers! haha I'm also curious if Van's will say to add a doubler as one of you mentioned, I have seen them do that before when I thought they wouldn't. I'll keep you posted.
 
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Jereme--
Take a deep breath. Relax. I assure you that it wont be the first pieces you'll have to replace. Everyone does it at least once, some of us more than that :eek:

Tom
 
Jereme--
Take a deep breath. Relax. I assure you that it wont be the first pieces you'll have to replace. Everyone does it at least once, some of us more than that :eek:

Tom


I stopped looking at my pile of mistakes with shame and started looking at them as lab experiments that led to the proper outcome. I will be ordering angle today that I need more of. I am sure that the last thing I ever do on this build, before flying, will be waiting for USPS to deliver a replacement for something I goofed up on.
 
Try bending it back with hand seamers, avoiding the edges of the dimpled hole. If you can get it close, take your squeezers and redimple the hole. The dimple die will reform the area around the hole. As an experienced sheet metal guy, I would have that fixed in about two minutes. If you mess it up further trying to fix it, you will have learned a bit more and then you can order a new part.
This really isn't that bad and is easily fixable in my opinion.
 
Try bending it back with hand seamers, avoiding the edges of the dimpled hole. If you can get it close, take your squeezers and redimple the hole. The dimple die will reform the area around the hole. As an experienced sheet metal guy, I would have that fixed in about two minutes. If you mess it up further trying to fix it, you will have learned a bit more and then you can order a new part.
This really isn't that bad and is easily fixable in my opinion.

+1 a little "shrinking" and you have it. Or - - you will have some extra material to make stuff for the remainder of the build. For perspective, I bought a top forward fuse skin just for use as a template. Shipping alone was $75, so you are getting off easy.

After all, building the empennage is still in the "training" category (like all of the first build).
 
Order snail mail. There's always something to do while you wait.

This. Shipping by regular mail to Winnipeg in Canada doesn't even take too long -- maybe a couple of weeks at most. And most of the delay is the border crossing. You're in Wyoming? I'll bet that won't take more than a couple of days.

Yes, there's always something else to do!

Cheers,
 
Shipping

This. Shipping by regular mail to Winnipeg in Canada doesn't even take too long -- maybe a couple of weeks at most. And most of the delay is the border crossing. You're in Wyoming? I'll bet that won't take more than a couple of days.

Yes, there's always something else to do!

Cheers,

Ooops. Sorry, I missed that.
I live in the mountains so it adds a day or two.
Lots of mistakes. They get retasked as new useful stuff. Flap spars made a really nice adjustable plans rack. Mistakes are just opportunities to design new projects!
 
By the picture, that doesn't look like too big of deal. Try repairing as the others have mentioned. If its not to your liking, then order parts.

I imagine Vans will tell you to build on but I may be wrong. I would think a lot of the load is carried by the skin and not just the spar and by the picture, I'm not so sure that the integrity of your spar has been compromised. Damage looks to be only on the flange from what I can tell.
 
Thanks for all the great replies guys. As many of you suspected here is the reply from Van's:

"I don?t see any reason that bending this back would compromise the spar, no deformation in the bend radios or the web of the spar. Flatten and build on."

I will try to flatten the bend and see how it goes. If I can get it back to straight which shouldn't be too big a problem I will carry on. The thing that makes me feel a bit better about this is not only is it a small bend but it is right between the two rod ends.
 
Well I think I have a fix I am happy with, what say you? I gave my dad a call to help me out with this one as he has been working with sheet metal for 30 years more than my 4 (he does HVAC). The first picture below shows how the bend in the flange was tweaking the spar forward. The ruler is placed on the bottom portion of the spar. (notice the gap on the left between ruler and spar)

2iu5fk1.jpg


The following picture shows the ruler on the top portion of the spar where the bend was at it's worst. This pictures shows a bit of deflection but definitely not plastic deformation as you will see in the picture after this one. (this forward bend of the spar will happen when the flange is bent)

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This next picture is the same top view and top of the spar after the fix has been made. You can still see a very small sliver of light but I believe that it is due to some deformation caused by riveting the doublers as it also shows on my other non-damaged spar. (left elevator)

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The following picture shows the spar from the front after the fix has been made. Can you tell where the bend was?

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In the next picture the drill bit shows where the bend was.

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And the final picture shows the spar as it nests with the skin.

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So what do you guys think of the fix? I am pretty happy with it and think that it is still a safe spar especially considering that the bend was between two hinges.
 
Nice work; build on! (however, we may need a word or two about your primer choice... ;-)
 
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