Kitfox iv wing repair

[Dusty]

I am in a position of needing to repair my port wing on a model 4 1200 damaged in an engine failure, ditching event
The good folks at kitfox can supply the parts, 2 spars /inserts and aileron etc.
We intend to remove the Spars and insert the new ones. Preference would be for a quick build wing but the freight to New Zealand for such a large item is eye watering.
Any hints and suggestions for spar replacement welcome.
I will also inquire about replacing both my ailerons with the later asymmetric style vs the symmetrical it currently has. Has anyone done this and is there any benefit to be had.
Cheers
Dusty

[taff]

I'm thinking a small wood chisel to get the bulk of the adhesive off and then thread a wire (safety wire) to slowly cut through between the rib and the aluminum?
Use it like tooth floss.

How about the fuel tank? This is going to be a tough one.
What is the adhesive holding that in. If it's the soft rubbery stuff, maybe the wire to slowly saw through this?
Are you going to order ribs as well?

[avidflyer]

The spars are 6160 2 1/2" OD aluminum tube with a .065" thick wall. I would think that could be bought in NZ or Australia. To get the spar and wood ribs seperated, I would imagine it would be best to cut the spars in pieces, so you are only dealing with one rib at a time. If you only have a 1" long piece of spar in the rib, you should be able to cut it in quarters and peal it off of the epoxy with some heat applied to the aluminum. Then use a dremmel or similar cutter to remove the epoxy. Front spar will come off easier, but I can't imagine pulling out the rear spar in one piece. And if you are replacing it anyway, it must be junk.... JImChuk

[efwd]

I would seriously consider just ordering the wing kit. Your already getting spars. I think building a new wing from new parts will be so much less annoying than trying to salvage parts. Shipping should be much more reasonable with the ribs in a box vs. the assembled wing.

[jiott]

I second Eddie's comment.

[alexM]

I know that with the wings on my Citabria it was technically possible to detach the ribs and slide the spars out. Although that is a gross oversimplification there are a lot of parts that can stay attached to each other in the process and it will still look like a wing sitting on the table.

I don't think you'll find the Kitfox wings to be the same at all. You can't get the ribs off without drilling out/de-bonding the drag/anti-drag tubes and at that point you're left with a pile of ribs held together by the trailing edge pieces.

Do you know when your wings were built? I ask because the adhesive used matters here.

My project came with new spars and internal extrusions. The plan of the previous builder, and the one I started with, was to get those ribs loose and re-use them on the new spars. You can get structural adhesive to let go with a heat gun or by sticking it in an oven if the part is small enough. I learned quickly that the old 3M structural adhesive needs WAY more heat to break loose than the EA9460 Hysol we use now. By the time the 3M stuff even started to give up the wood was starting to scorch. I quickly realized that by the time I perfected the technique I would have 100+ hours in salvaging ribs and I would still have lost some because they'd be burnt.

I had just typed up a part where I suggested chopping the spars near the ribs as someone else had suggested above. The long spars serve as a heat sink to draw heat away from where you're working, so by cutting the spars into short pieces you could toss the ribs into an oven one by one. Working carefully you'd have way less risk of burning the wood.

But that won't work because the rib cap strips are also bonded with structural adhesive! This stuff is thermoset resin so once it is heated to the stage it gets rubbery it does not recover. It's done. Finito. Even if the cap strips were retained by the staples and they "looked fine", the adhesive would be compromised. I've read where people say you can heat up structural adhesive to reposition a crooked part. That is mythology. Yes, you can reposition the part but the glue is permanently compromised and this is true of any two part adhesive. The only way you might get lucky here is if the ribs were made using the old 3M adhesive but the builder used EA9460 to assemble. You've got nothing to lose in testing a rib with a heat gun to see how it goes.

I'm going to suggest you do what I did and order new ribs. The shipping that is killing you is that long crate with the spars. A plan B might be to source the spar tubes locally and order the internal extrusions from Kitfox. That would be a 6' crate instead of 13'. The difference in shipping might pay for those ribs.

[Eric Page]

I'll second Alex's comment about the old 3M Scotch-Weld being impossible to remove. My Series 5 came with a dented elevator push-pull tube, so I needed to fabricate a new one. I tried to remove the machined end fittings from the old tube to re-use, but even with a propane torch the Scotch-Weld would not release. I boogered the fittings up so badly in the attempt that I ended up ordering new ones from Kitfox.

[taff]

I remember;
Installing the I beams inside the wing spars. The instructions made sure that no rough contaminate (grit and stuff) entered the spar when sliding the I beam into the opening.
For fear of damaging the aluminum, causing stresses.

If you drill to remove the rivets, there would be so much burr that trying to tap and push the I beams out would be about impossible.

I second the others and suggest the full monty, in bits to save on package size. Would it save on freight ?

If you don't have the instructions and drawings on assembly, you will need them.

[Dusty]

Thanks for the replies
I assume hysol (1994 kit) ,chopping the Spars individually and replacing one at a time may be an option. I will get 2 spars and inserts from kitfox.
My rear spar maybe OK we wont know untill the bent front spar is removed or temporarily straightened.

Any specialist aluminum has to come from overseas and I am happy to support kitfox.
My aileron doesn't look right so will be replaced and the Spars can be boxed together.

The wreck has just been released by my insurance so I am still assesing.
I will get a price for ribs etc if cutting doesn't look feasable

Any ideas on using the later style ailerons?

[DesertFox4]

Dusty, Per the New style flapperons, I’d stay with the symmetrical ones. They should preserve your lighter feel and quicker roll rate.
First time I flew the asymmetrical flapperons, I really noticed the higher control loading in the roll axis especially after years in the model 4s.
Now, after years in the newer models, I’ve become accustomed to the feel of the asymmetrical flapperons and have zero complaints.
Just not quite as “sporty” in roll.

[alexM]

I second the others and suggest the full monty, in bits to save on package size. Would it save on freight ?

Shipping to Australia is INSANELY expensive and I imagine New Zealand is the same. One of my side activities is designing and prototyping motorcycle parts, which eventually get built by others. Shipping a motorcycle engine sump guard to Australia was $450 USD. They guy insisted he wanted one of my prototype units which I valued at about $200. It shipped in a box that was 12x18x10 and weighed about five pounds all up. I quoted DHL, UPS, FedEx and USPS. USPS was the cheapest by a long ways at that $450 price .

Second craziest shipping costs are to Canada. Also shipping a couple of very small motorcycle parts recently (windshield spacers made of UHMW) it was about $15 USD to Belgium and the UK and over $50 to the middle of Canada. The quickest to arrive was Belgium. The last arrived weeks later in the UK.

A spar crate to NZ? Has to be eye watering.

[Eric Page]

I assume hysol (1994 kit)...
My Series 5 dates from April 1995 and used Scotch-Weld, so the change to Hysol was definitely after my kit was produced.

[taff]

I just had a brain gush!

Your insured for that repair.
To repair, the aircraft needs parts.
To acquire the parts you maybe need the insurance to settle also for shipment of parts.

What's the point of insurance, if your paying an expensive portion of the repair. That should be built in to the claim? Or negotiable.
Think of any repair shop. They provide the insurance co. a price/cost for doing the repair. If they need parts, Piper, Cessna or Kitfox. the shipping is included into the total repair estimate.

Maybe this could work?

[avidflyer]

Dont want to speak for someone else, but say you are insured for $30000 hull coverage. Insurance company says to themselves it will cost more then that to hire someone to repair the plane. They take the cheaper route, and pay you the $30,000. They let you buy back the plane for what ever is agreed to. For instance, say it's $5000. All you have left to repair the plane is $25,000 now. The question then becomes, how do you do that without breaking the bank ($25,000) JImChuk

[Maverick]

Something else you might consider is to build your new ribs yourself. If you can obtain the plywood you could salvage one of the ribs from your old wing and create an aluminum template of the wing from it and then use it to router out all the ribs you need. Getting the plywood shipped (if you need to) might be easier if it is cut down to smaller size sheets since package size has a lot to do with shipping cost. It also would give you some options for the wood type, i.e. a five layer marine grade plywood could work. EAA has a great book on building with wood that has info on selecting wood that can be used in lieu of birch or spruce. When I built my first homebuilt from scratch I used Douglas Fir marine grade plywood for the ribs and Douglas Fir planks that met the EAA criteria for the spars. I bought all of it locally. When I made my ribs, after getting my template made I made a set of 24 ribs in a day.

https://www.eaa.org/shop/product-detail?i=941&pi=926&pr=2516729

I don't know about governmental restrictions there so this might not even be an option but if so this could save you a lot of time and money. However, if you are ordering spars, I would just order the entire wing kit less anything else that comes with it that you might not need like struts.

I wonder if this would help get the fuel tanks out? DesertFox4 turned me onto this for cutting PVC and I wonder if it could somehow be used to cut through the stuff holding the wing tank to the spar.
https://www.amazon.com/General-Tools-858-Stainless-Serrated/dp/B002FYUNGA/ref=asc_df_B002FYUNGA/?tag=hyprod-20&linkCode=df0&hvadid=309832851244&hvpos=&hvnetw=g&hvrand=7071836857136207344&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030004&hvtargid=pla-420978968769&psc=1&tag=&ref=&adgrpid=64417494871&hvpone=&hvptwo=&hvadid=309832851244&hvpos=&hvnetw=g&hvrand=7071836857136207344&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9030004&hvtargid=pla-420978968769
Maverick

[Jim2Fly]

Murle Williams suggests removing hysol by softening with a heat gun.

[efwd]

If I were to try this I would cut the spars into segments and try heating the spar from inside exclusively as to avoid burning the wood. My heat gun (Steinel) can be turned up to temps adequate for soldering, 1200F. Expensive but You will save a gob of time once your proper temp is determined to release the Hysol. Having a digital temp control makes putting Oratex on a much easier process, that is how I came into this gun.

[TJay]

The spars are 6160 2 1/2" OD aluminum tube with a .065" thick wall. I would think that could be bought in NZ or Australia. To get the spar and wood ribs seperated, I would imagine it would be best to cut the spars in pieces, so you are only dealing with one rib at a time. If you only have a 1" long piece of spar in the rib, you should be able to cut it in quarters and peal it off of the epoxy with some heat applied to the aluminum. Then use a dremmel or similar cutter to remove the epoxy. Front spar will come off easier, but I can't imagine pulling out the rear spar in one piece. And if you are replacing it anyway, it must be junk.... JImChuk

Don't forget they are Drawn Tubes if your sourcing them else where

[David47]

Thanks for the replies
I assume hysol (1994 kit) ,chopping the Spars individually and replacing one at a time may be an option. I will get 2 spars and inserts from kitfox.
My rear spar maybe OK we wont know untill the bent front spar is removed or temporarily straightened.

Any specialist aluminum has to come from overseas and I am happy to support kitfox.


Strongly recommend you buy the spars from Kitfox. Aluminium suppliers here in Australia only supply in 12 ft lengths and if your KF5 has the same wing as the KF7 then suppliers other than Kitfox won't get you the length you need. I know this because I had an "incident" on my KF7 wing build and ordered locally - Kaiser manufactured in the USA. I had to design an extension to the outer section for an extra 18". Also, as already suggested by Jim Chuk, a heat gun will soften Hysol if that's what was used. Any other adhesive used in the original build - don't know.

[Dusty]

I have ordered the Spars and inserts from kitfox so I can be assured of the quality.
I have also ordered the rivets from kitfox.

Using a heat gun on the inside of the old spars makes easy work of removing the old glue. The fuel tank is held in with a mixture of structural adhesive and soft caulking glue.
I haven't progressed much with the wings until the parts arrive as the wing will be very fragile to move if I get too far ahead of myself. Overall this doesn't appear to be too big a job but I am using the waiting time (4-6 months) to learn what I can regarding rigging etc.