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J-Stiffeners: doubler ok???

dustin_96

Member
Ok bonehead move: I mis-drilled the lower stiffener for the right wing. The left one was done correctly but I didn't tape off the correct holes on the right wing.

Is it acceptable to use some extra stiffener material to create a doubler?
 

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Offhand I would say that is is OK to create a doubler, as long as the doubler includes the bend, and at least one hole on either side of the missdrilled hole, but best to check with Vans support.
 
Repairs

They are cheap, why build a plane that has repaired parts in it before it even flys?

I've "repaired" several parts during construction, including for kit parts that did not fit and drawings that were unclear as well as my own boo-boos. This was standard expected practice for early kits and there's nothing wrong with making a repair if it is done properly.
J stiffeners are cheap but the shipping will be the killer because of the length. So I believe it's worth ordering extra stiffeners, as well as angle stock, to be included in a shipment when ordering a kit.
As for this specific repair, I think a doubler would be fine and AC43.13 has enough guidance for how to do it.
 
You could also just make a new stiffener if you have the metal. My kits have always come with some aluminum strips that I think they called “trim bundle”, and were (are) 3 or 4 feet long. Just bend it in your store bought, or home brewed bending brake, trim to correct width and you’re done. A 2 X 6 bending brake should have the perfect 1/4” bend radius on it’s edge.
 
Plan

Just as a matter of clarification I ordered replacement parts soon after discovering the issue. I just thought I would put the question out to the group to help me gauge if it is worth waiting for the replacement parts and paying the cost or to just put doublers on to repair it and go on down the road.

Thank you for everyone's responses.

I'll figure out something else to work on while I wait. :)
 
They are cheap, why build a plane that has repaired parts in it before it even flys?


I inspect and take delivery of several new aircraft from Airbus and Boeing at my day job. Both manufactures do this on a regular bases dependent on the specific issue...So not uncommon.

However, in this case, I think you have a point. Part is cheap and easy to acquire. Becomes personal preference here.
 
I've "repaired" several parts during construction, including for kit parts that did not fit and drawings that were unclear as well as my own boo-boos. This was standard expected practice for early kits and there's nothing wrong with making a repair if it is done properly.
J stiffeners are cheap but the shipping will be the killer because of the length. So I believe it's worth ordering extra stiffeners, as well as angle stock, to be included in a shipment when ordering a kit.
As for this specific repair, I think a doubler would be fine and AC43.13 has enough guidance for how to do it.

Strongly agree.

If you can get replacements cheap enough and fast enough then do so.

Otherwise a Vans approved and legal fix is totally fine. A certain YouTube builder has recently posted a similar issue with the J channel and the fix they did.

Note, their fix may be different and may not suit your purpose etc etc. But the principle is the same. If you can make a safe repair based on engineering advice from the manufacturer why would that not be acceptable?
 
I used the wrong length raw stock (two cut from two 6 ft. pieces instead of both cut from one 8 ft. piece) to make my short wing J-stiffeners and decided to order new stock. Vans sent me a couple of 6 ft. J's ($13/each) within 10 days and the shipping was reasonable from Aurora to California, around $23 I think. They were delivered in a 1 1/2 in. PVC pipe. Total price was around $55 or so. This was about 3 weeks ago.

If you chose to repair, then you'd need to use a doubler that captures at least two fasteners on either side. The doubler needs to be at least as thick as the parent material, or preferably the next gauge size up. The holes are too close together to have any structural load carrying capability. Since this is the lower stiffener it's going to be carrying predominately tension load. The closer it is to the wing root, the greater the wing bending moment which may or may not translate into higher stress in the stiffener. You need to watch for interference issues in the ribs with the double if it runs through a rib.

Since you don't need those J's until you rivet the wing skins on, I think it makes more sense to get new stock. You'll just have to delay installing the nutplates on that spar until you get the new pieces and drill them properly.
 
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J stiffeners are cheap but the shipping will be the killer because of the length. So I believe it's worth ordering extra stiffeners, as well as angle stock, to be included in a shipment when ordering a kit.
Van's ships J stiffeners and other long skinny parts in PVC pipe, and the shipping cost is actually surprisingly reasonable. (Ask me how I know ;)) And I agree that ordering spare J stiffeners is a good idea. (Ask me how I know ;))
 
To put a bow on this thread, I made the mistake on Sunday afternoon and ordered the replacements that evening. I just received notice that they have shipped! That's three business days (that happen to be the week after osh)!!! I'm very impressed.

Cannot wait to fly this thing!
 
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