need your experience

[Richard31]

Hi team,

I am interesting in a 2nd hand kitfox from 1996. i visit the airplane last week end and i take 2 pictures of something strange regarding the left root rib. here attach the pictures. have you already see this detachment of the bonded joints between wing ribs and spars ?. thanks for your help. does it exist a way to resolve the issue or does it means something more critical.

regards and thanks for your help !

[avidflyer]

At first glance, I wonder if the wing was swung into the overhang on the skylight part of the windscreen? Is there a wrinkle in the fabric by that rib? It's handy that there isn't a fuel tank in that wing, can you see if the other ribs are loose as well? If you were to decide to install a wing tank, it would be fairly easy to remove and replace that rib then when you had the fabric pulled back. JImChuk

[Dave S]

Richard,

There are probably several ways this could have happened - inadequate preparation on assembly, trailering the plane with the wings folded if the wings were not braced; and, there is one question (but not an answer) related to flox vs microbaloons per service bulletin 7 which relates to kits shipped around 1991.

http://www.kitfoxaircraft.com/images...etins/SB-7.pdf

No matter the cause, looks like further investigation is in order to determine if other ribs are separated and how extensive the problem may be and what might be necessary to effect a repair.

[avidflyer]

Dave, did you ever hear of any follow up information to that link you posted? JImChuk

[Dave S]

Jim,

As far as I know - the original SB 7 was the only information posted by the previous kit manufacturer ownership - I don't think there was any follow-up.

I am thinking somewhere there was some list discussion - and it would have been back a while; but, that may have been on the old Matronics list.

Sorry

[Bluebird19kf]

Pretty sure I read a follow up to that SB and it basically said that either flox or microballoons were fine to use.

[Guy Buchanan]

Doesn't look like the root rib braces are installed correctly. There are supposed to be some internal aluminum tube braces coming from the front and rear spars to the root rib top and bottom to make sure the fabric tension doesn't bend the root rib. Are they there? Are the root ribs straight fore and aft?

You've got some repair work on your hands there. First you'll have to stabilize the rib with some temporary braces, then grind all the existing epoxy off the forward and aft attachments, then prep the wood and aluminum for epoxy, then epoxy the forward rib break, then straighten the root rib using additional permanent internal braces, then epoxy the rib to the spars, then do cosmetic clean-up.

The big problem will be if the builder didn't install the braces, then bowed the heck out of the root rib during fabric shrink. You'll never be able to straighten it and will have to re-cover the root bay or the entire wing. (Probably just the root bay.)

PS. Check both sides. Probably the same inherent problem.

[avidflyer]

In the first picture, it looks like there are 2 aluminum tubes attached to the rear spar, maybe about a foot in. I figured they were the rear braces for the butt rib. Would have been nice to see the complete end of the wing to see if there were any pop rivets showing that would have been holding those braces in place on the rib. Fabric does pull pretty hard when shrunk, no doubt about it. JImChuk

[jiott]

Those braces visible in the picture look like the spar cross bracing tubes; they don't support the center of the rib against the pull of the fabric. What Guy is asking is are there additional support tubes not visible in the photo that go to the center of the rib, similar to what is done on the opposite wing tip end. With a fuel tank in the root bay we put small wood blocks from the tank side wall to the rib for support, but with no tank and if no support tubes, that could easily explain the damage that we see.

[Esser]

It is a concern and you could have a whole wing repair on your hand. I would offer him what ever for the plane he is asking minus 4 or 5 thousand if you are willing to repair it