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FWD LH wing spar/fuselage attach holes

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Posted

Hopefully the pictures posted. I have a problem, the fwd. wing spar attach point holes were not drilled correctly and don’t line up perfectly with fuselage attach point. The fwd. spar holes are approx. 1/8 of an inch aft of the fuselage attach point. I can’t get the pin to drop through. My plan is to remove and weld a new attach point on the fuselage, I figure this will be the easiest and safest fix. I'd remove the current fuselage attach tube and weld a new tube in 1/8 aft, using the same holes, no splicing of tubes. What do you think? Does my corrective action sound good?

 

 

 

 

IMG_0102.pdf IMG_0106.pdf

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Posted

Some other folks have had to bend the tube to align and correct this problem

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Posted

The tube is so short and stout I wasn’t sure how I would be able to bend it.

I'll have to put some thought into that. I'd rather do that than weld it. Thanks for the impute.

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Posted (edited)

Your idea of rewelding might work best - use mild steel vertical tube and ream after welding - don't quench. 

OR, measure - put a torch on it - bend it - measure - don't quench.  Get it close as possible - use round file on wing spar to finish fit if need be - fore and aft not that critical - need tight fit right / left - this way could change wing angle, but maybe not enough to matter.

EDMO

Edited by Ed In Missouri

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Posted

I bent mine, heated with a torch to cherry red then bent with a 1.5" by 4' pipe with a tee handle on one end and a slot cut in the other to fit over the pin tube.  Just do a little at a time and check in between.  I build a checking jig first out of square tube with bolts welded to it that fit the wing holes.  Get long enough bolts, drp them into the wing pin holes and space them above the wing until the heads touch the square tube, then weld the heads.  Then you can use the jig to check your bending and tube alignment instead of the wing itself.

post-75-0-92667000-1396420669.jpg

post-75-0-91555900-1396420731.jpg

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Posted

Excellent idea, I like the jig part. I see you have gussets on the bottom, I may do that for piece of mind. Thanks!

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Posted

just to give a different option you could make as small bushing weld it to the steel reinforcement plates, enlarge the hole in the aluminum preferably with a file keeping it a nice tight fit for the bushing to go through and put it all back together. I hope this made since??? please see attached crappy picture for reference

post-352-0-71759300-1396448730_thumb.png

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Posted

Great Idea!  At one time, green sky adventures made a reinforcing "ring"  it was a machined steel bushing that was used in place of the two riveted "tangs".  just a thin pipe that slid inside the spar to add that reinforcement all the way around the tube.  This was done to fix sloppy bolt holes, or for the guys that went to heavier engines and wanted to sweep the wings forward.  If you have a lathe or a machine shop close by, it wouldn't take much to turn down some pipe to slip inside the spar so you could line the holes up perfectly.  At that point the holes in the spar for the pins become a mute point and you could over size them so the pin would drop in, yet be held in the correct position with the "liner"

 

:BC:

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Posted

I really like the idea of the insert for the spar. I noticed the other day when I had to partially fold the wings back that the right wing forward spar had an oversized hole in the top of it. Basically it's like there were two holes drilled next to each other. I presume to correct almost the same issue you have. I was wondering what, if anything was needed to fix it. The wing fits tight and doesn't move in any direction but I still don't like having an area that may have increased stress on it due to not capturing the pin correctly.

 

It seems to me that the tab with a drop in bushing would solve the problem nicely in both of our cases, plus as a bonus would keep the aluminum from ever being able to wallow out. Thanks for the great idea High Country!

 

Just curious thought about riveting it in. Is there anything about not putting in rivets on top or bottom of the spar for strength issues? I know I don't want any holes in it but I'm wondering about strength with rivets?

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Posted

The little reinforcing tabs are already supposed to be riveted in as well as hysol so no worries there the rivet holes are a non issue. also you can just file out the hole bigger with a small round file, I used a chain saw file, to fit the bushing how/where you want it and then just hysol it in, if its a tight fit the stress is being exerted into the spar and reinforcement material anyways so the hyhsol is mainly just holding it into place when wings are folded back. make it extend up through the top if you want and add more hysol or a second steel strap. this would eliminate the need to remove the current plates.

 

-Robert-

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Posted (edited)

Not a good idea to drill holes in the vertical position on the spar - However, with the steel reinforcement there should be no stress on the tube .   I don't see any need to drill there when you can offset two rows on each side of top and bottom.

Yes Leni - I had totally forgotten about the steel tube insert that was a fix listed a long time ago - makes sense to me!   And, this should be glued in as well as SS riveted.

EDMO

NOTE:  If you put a steel tube insert into the spar, don't square the end toward the wingtip - this should be more of a V-shape and rounded to prevent a total round stress point.

Edited by Ed In Missouri

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Posted

just to give a different option you could make as small bushing weld it to the steel reinforcement plates, enlarge the hole in the aluminum preferably with a file keeping it a nice tight fit for the bushing to go through and put it all back together. I hope this made since??? please see attached crappy picture for reference

I do understand your fix High Country, it’s a good idea. I’m going to have to check to see if the fuel tank attachment area covers the rivet holes for the reinforcement plate. I’m glad I finally chimed in on this web site, the knowledge on the Avid is impressive. It’s much appreciated, thanks all.

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Posted

Ed,

Are you talking about an insert going horizontally into the spar or vertically into the spar pin hole that needs to be V'ed? I'm not sure I understand.

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Posted (edited)

Kenneth,

       It is a horizontal tube inside the spar that replaces the inserts for the attach pin - I cant describe it very well, but you want the end toward the wingtips to be a sort of rounded fishtail instead of a square cut.

       A short piece of 4130 or mild steel tube that is a slip-fit to epoxy / rivet to the spar, and should be painted on the inside.

ED

Edited by Ed In Missouri

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Posted

I'm fairly sure my wings already have that done to them. Just that the right one wasn't properly drilled the first time so the hole was enlarged. Thus the idea of inserting bushings to take the stress off and fix the oversized hole all at the same time.

 

That did clear it up. Thanks

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Posted (edited)

If you remove the inserts and put the tube in place of them, you can just drill the tube thru the same holes as the original - might have to go to next size rivets if you have enlarged the holes.   Drill a 1/4" hole which you 'think' will match the attach fitting, and start enlarging it with a round file to get it to match - you can get one side close and then finish by drilling and reaming all the way thru. 

Be sure your wings are square or equal as well as the dihedral.

EDMO

Edited by Ed In Missouri

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Posted

Now I understand what you're saying. I didn't think about removing and replacing the inner tube to redrill. I think the easier solution is a small bushing though. Not sure how easy it would be to pull the tube out of the spar. Good thought though. I'll have to look at it closer and see if I really need to do anything, but this thread gives me some ideas.

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