Broken Flaperon mount?

31 posts in this topic

Posted

Sadly on my first pre-flight I found a broken flapperon mounting point above the anti flutter counter balance.  It looks to have been repaired before. image.thumb.jpeg.67384d52f51656dfdfed5b4 I have read of several ways to repair it my question is what fabric system system was being used or recommended by avid in 1990.  That is what the aircraft logbooks say they used what the factory manual recommended. 

 

Thanks in advance

 

Jamie

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Posted

Are you sure that the rib is cracked and not just the paint?  Can you physically move the rib tail up and down?  JImChuk

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Posted

Unfortunately it is cracked through and moves

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Posted

That's not good then.  I have fixed some broken rib tails on my latest Avid Flyer rebuild.  Just now, I can't seem to find the post I made describing it.  I'll dig some more.  I cut a bunch of replacement rib tails from the 1/4" plywood I got from Aircraft Spruce, and have quite a few I haven't used.  It is going to require that you cut into the fabric quite a bit to fix your wing though.  JImChuk

 

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Posted

Here is a link to the messages I posted on how I fixed my rib tails.  JImChuk

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Posted (edited)

Since no one on the Avid side answered about the finish on your 1990's bird, I am guessing that Poly products was used on it the same as Kitfox used.  I spliced my broken ribs about the same way Jim did, except that I sandwiched .060 aluminum on the wood rib, all the way from spar to end of the tails, (glued with Hysol 9460 and riveted).   EDMO

Edited by EDMO

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Posted

Looking at the rib tail, makes me wonder what the reason for the breakage is. Does the flaperon move smoothly through its full range of travel with no binding or movement in that spot? Someone chinning themselves on the weight? Fixing the rib shouldn't be too big a job, wondering if it's going to break again, something else.

Jack

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Posted

Edmo 

 think I will try to sandwich it as well.  How long ago did you do your repair and any issues since?  If I use a poly system solvent to peel back the tape can it cause any damage if it isn't a poly system product?

 

jack.  It moves smoothly throughout its range of travel.  All I can figure was hangar damage. Repaired poorly and maybe stressed by trailering. 

 

I hope it doesn't break again   One with rot caused a crash in the Midwest.  I think the guy ended up in a river I think   

Thanks guys

 

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Posted

It looks like your rib tail was repaired once already.  Are all the rib tails 3 layers of plywood like this one, or just this one?   Normal rib tails are just one layer of 1/4" plywood.  To take the paint off, use MEK for starters.  That is what poly fiber recommends for paint removal.  It works on ceconite also, but not as well.  Was just looking in my MK IV Avid manual, and it talks about using Super Seam glue to attach the fabric. Then it talks about using nitrate dope to attach the tapes.   That I believe is the ceconite process.  Poly fiber uses Poly tac for glue and poly brush for installing tapes.  JImChuk

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Posted (edited)

Machinist, (and IR12)!

My wings and plane haven't been finished or flown since the repairs were made, but I think the rib tails have to be stronger than the originals - I did this to all of the hanger ribs, good ones too.  Kitfox SB showed a similar strengthening to comply with British standards, but I think they used .025 aluminum, maybe with a 1/2" 90 degree angle bent at the top, and about 8 rivets, I think.              I didn't bend the .060 aluminum for mine.   Jim Chuk has flown his repaired ribs. 

My Kitfox 4 manual says it used 1.8 oz. Ceconite fabric, but Stits (now Poly) process for finishing, but not to shrink according to Stits because the fabric is different.  Hope this helps.  EDMO

Edited by EDMO

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Posted

Actually, I have yet to fly the Avid with the repaired rib tails.  :-)  JImChuk

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Posted (edited)

Yes Jim - I am corrected - It still looks like a good repair - Guess you are having too much fun with the long-wing Kitfox! :BC:  EDMO

Edited by EDMO

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Posted

Does anyone have a STOL wing open they could take measurements of the triangle to the tail of the flapperon so I can cut some aluminum to fit in and sand which my splice.  My plane is an hour away and was hoping to get the aluminum cut before I get there.    I think I will reinforce both sides where the counter balance is. 

 

Thanks

 

jamie

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Posted

This is what a rib looks like.  Where are you going to put the aluminum?  It looks like you have doublers of plywood already added onto the rib tail.  JImChuk

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Posted

Jim,  I think he was going to make a new tail and insert it like you showed in earlier photos, and aluminum sandwich from spar to tip?  EDMO

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Posted (edited)

My plan is to cut out the damaged wood and put in new wood and sandwich that with aluminum

 

jim

edmo is exactly right that is my plan 

Edited by THE MACHINIST

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Posted

My plan is to cut out the damaged wood and put in new wood and sandwich that with aluminum

 

jim

edmo is exactly right that is my plan 

So - you need a full-sized drawing of the wood rib without capstrips from spar to tip - I only have some Kitfox short ribs.   EDMO

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Posted (edited)

Where are you located Jamie?  I have a bunch of extra pieces cut from 1/4" aircraft plywood.  (7 ply at least)  I could send you a set like I put on my ribs.  (Center piece, plus 2 scabs, one for each side).  Go back and look at my rib repair if you like in the 'Broken rib tail repair' post.  I made a jig to cut the angels on a table saw, and so cut a bunch of sets.  I have more wings to repair, but it wont be for  a while.  I could easily free hand one or two more sets.  JImChuk

PS  Just went back and reread the broken rib tail repair post, and I see it was 12 ply plywood I used. 

Edited by 1avidflyer

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Posted

Jim

 

thanks

 

I called you back but it rang and rang

is there any substitute for hysol 9460 that I could buy at Home Depot or Lowes?   I can't find hysol locally and was hoping to do the repair this weekend. 

 

Thanks

 

jamie

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Posted

Hi Jamie, maybe you dialed it wrong or something, I've been home all evening.  Sorry I missed you.  Try me again tomorrow.  I'll be around from about 7:00 AM your time.   Not sure I would recommend some other type of epoxy than the Hysol or Scotchsweld 2216.  As far as I know, that's been what Avid and Kitfox have recommended or supplied with their kits.  JB weld might work, but I'm not so confident of it that I would want to trust my life on it.  I just don't know one way or the other.   And not to be to blunt, but that could be what you are doing.  If the flaperon falls off in flight, it will get bad real fast.  Maybe it's just as good as Hysol, but I don't know that myself.  If you are careful and do it right, it will be a way better than getting in a rush and then "hopefully" living to regret it.  Like I said before, looks like the rib was patched already.  It didn't break for no reason.,  Maybe it got hit real hard, maybe it's rotten, or maybe something else.  Whatever the case, you will be better off and much safer if you don't get in a rush, but fix it right.   And maybe you can fix it right in a short time, but the main thing is FIX IT RIGHT :-)  Call me in the morning if you like.  JImChuk  218-254-2404

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Posted (edited)

I think you can order Hysol 9460 in a smaller tube - Spruce, Wicks, Kitfox?  The last time I bought the 2 quart cans kit from Kitfox it was about $135 shipped.   I believe Joey used E-50(??) for a non-structural repair.  Spruce sells 9430 in small amounts, and I think it might be OK, but I don't know if I would use it for a flaperon hanger rib repair unless I read more specs on it - I think big difference is 4:1 or some mix, while 9460 is 1:1 mix.  I haven't used 2216, but Avid and Kitfox used it before changing to 9460.   JB Weld cracked when I repaired some aluminum with it.  ???   I agree with what Jim said in post above.   EDMO

Edited by EDMO

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Posted

There are a lot of different things that fall under the "JB weld" brand.  Some may or may not be suitable.

As I understand it, you plan to glue in new wood and then reinforce the joint with aluminum? Bonding aluminum to wood really should be done with proper adhesives and preparation - you have issues with different thermal expansion rates and corrosion at the aluminum / adhesive boundary. I would stick to a product that is known to work.  If you wanted to do a wood to wood repair then something like a West System epoxy from your local marine supply could be expected to work, but I wouldn't trust it for the wood / aluminum interface.

 

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Posted

When I broke my end rib tail off during an off road excursion I used a piece of the cap strip on each side, a few bamboo BBQ skewers and Gorilla glue to fix it.  That was over a year ago and its still going strong.  I also used gorilla glue when I originally replaced all the rib tails on mine in 09.  I did several tests using T-88 epoxy, 30 minute hobby epoxy and gorilla glue on the plywood and the gorilla glue outperformed them all by a wide margin!

Attached are the pics I took right after I got back from the trip.  I have since cleaned it up a little, sanded them down and painted it.  The new bushing material for the end of the flaperon was a spout off an old gas can.  I cut it to length then had to sand down the OD so it would slide inside the hanger but it worked perfectly.

 

 

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broken hinge small.jpg

gas can small.jpg

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Posted

I guess I will order the hysol what size do you think I need to repair both sides with the counter balance (one on each wing) by sandwiching aluminum on both sides?

 

thanks

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Posted (edited)

I guess I will order the hysol what size do you think I need to repair both sides with the counter balance (one on each wing) by sandwiching aluminum on both sides?

 

thanks

I don't even know how big a 50 sillyleter tube is!  Does this make 100 ml when mixed 1:1?  250 sillyleters is about 1/2 pint.  Be sure and order some microballoons  to mix with it to insure that the aluminum is isolated from the wood to prevent corrosion - (or, am I thinking about steel to aluminum on that?)  (oh well, guess they are good on a sandwich!) 1/2" long Stainless pop rivets should work, but I used aluminum.   EdMO

Edited by EDMO

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