What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

J-Channel In Tailcone Has Cracks

D

drewhottub

Active Member
I have a few cracks in a j-channel, near the shop head of some rivets. What makes this special though, is the size of rivets I used.

(I used AN426AD5-5 rivets and 10 out of the 13 rivets, of this size, have cracks in the j-channel metal, right around the shop head).

Please see my below pictures, for more details, AND MY QUESTIONS ON THIS TOPIC, for the VAF community: (click the link)

https://picasaweb.google.com/drewho...authkey=Gv1sRgCJey8vrOvuTY9QE&feat=directlink

Best Regards,

Andrew
RV-10 Builder 41078

[ed. Welcome Andrew! dr]
 
Last edited:
As Mike said, call Van's. My guess is the force required to drive those 5/32 rivets is more than the thin skin and j-channels can take.

-Rob
 
I don't know what Van might say but, to me the rivets look too short. The anvil that forms the shophead should remain Just above the sueface Of the parent metal.

John D.
 
Welcome to VAF!!!!

John, welcome to the good ship VAF:D

Love the name of your town;)

Good to have you here, enjoy!!
 
Here's why I used AN426AD5-5 rivets...

Bob, I used AN426AD5-5 rivets, because I kept messing up.

Basically the chronology of events was:

1. I started out back riveting the J-channels using the AN426AD3-3.5's.
2. I messed up the shop heads, and had to drill them out.
3. I tried the AN426AD3-3.5's again, but noticed that the shop head wasn't engaging very well due to the hole now being slightly oversize.
4. I then drilled a 1/8 inch hole and re-dimpled for 1/8 size rivets, but forgot to deburr. I riveted in AN426AD4-4's, but noticed those tiny little cracks again, near the shop head.
5. So I drilled the AN426AD4-4's out and decided to use a #21 drill to make the hole even larger (to try and get past the cracks).
6. I then deburred, and dimpled the holes up to a 5/32 dimple, and riveted in the AN426AD5-5's.


Also, Here was VAN's response to what I have done.

Without seeing the pictures that I've linked, for you all to see, above; Ken, at VAN's says that the rivet's are fine, and that I should just leave them alone.
Since the cracks are in the j-channel near the shop head, and not in the skin, Ken encouraged me to not worry and to move on.
Ken made it very clear that the skin is what bears most of the loads, and that the flimsy j-channels are just there to make sure that the skin holds
it's shape, so that it can indeed bear the loads successfully.

Also, I have a friend building his Cozy Mark IV in my garage. This friend has his Engineering Mechanics degree from University of Wisconsin at Madison.
He is of the same mindset as Ken at Van's -that the skin bears the loads, and that I don't need to worry.


Still though, I want to get lot's of opinions on this, since it is imperative that I build this airplane correctly.

-Andrew
Builder 41078.
 
Last edited:
Andrew,

Good job on the pix. It looks to me like some of the rivet shank got expanded between the J-stringer and fuse skin. This can happen when the two skins are not held tightly together when riveting. Hard to know the best fix so I'm with the others, call Van's and point out to them the bulge and cracks around the rivet on the J stringers.

In the meantime, build on!
 
Actually the j-channel abuts perfectly to fuse skin...

FYI: I Should have included this in my photo album, but the J-channel abuts perfectly to the Tailcone skin. I'll go home and take a picture of this, and add it to my photo album, but in the mean time, please just know that I have already checked for this failure mode -and all is well! Cheers!

PS: Jerry Cochran, If you're concerned with the height of the shop-head being so short, I think that just had to do with the fact that I may have run the rivet gun too long, on it!
 
Last edited:
Get some univ and cs CherryMax rivets...

They will come in handy and do not swell as much as solids and can be used interchangeably.
 
Here is the solution that VAN's recommended

Please see my "link to the pictures", yet again, because I have added the solution that VAN's recommended.
Essentially the solution was to properly drill, deburr, and dimple an additional length of J-channel to be placed over top of the original J-channel.
Again, please see my newest picture (added 1-March-2011) for more details!

Here is the link to my pictures, again ---> https://picasaweb.google.com/drewho...asCracksAroundOversizedRivets?feat=directlink
(Note: This link was fixed on Tuesday, March 1, 2011 at 10:47a.m CST )

-Andrew
 
Last edited:
That link is broken, but here is the photo.

That was the same solution I was thinking of too.

Phil

P1030252.JPG
 
How did you embed that picture?

Phil,

Thanks for the reply! I fixed the link!

Also, how did you embedd my picture into this string? That is really neat!

-Andrew
 
Long story short you take the URL of your photo and bracket it with
.

Like this:
 
One thing. I noticed that you installed the snap bushings for the rudder cables already. You'll want to leave those out until you actually pull the cables.

The end of the rudder cables will not fit through the bushings and you have to deform them (by squeezing) to get the cable-ends through.

So you have to:

1) Squeeze the bushing into an elongated egg shape.

2) Push the cable through the snap bushing and then through the hole in the aluminum.

3) Then push the bushing into the hole.

It'll save you a little frustration if you go ahead and remove them now while you have really easy access to them.

Phil
 
Phil,

Thanks for that thought. I think either way I'll have to squeeze the cable ends, if want the cable to pass thru those snap bushings.

On a side note, I'm building along side a Cozy Mark IV builder, who happened to have a little extra epoxy. Since his resin doesn't react with the Aluminum or Primer and Top Coat that I used, I went ahead and epoxied the Snap Bushings in.

In other words, there's no getting them out!

Thanks any way, though!

-Andrew
 
Oh no..... They must come out. There is no other way.

Good luck.


drewhottub said:
Phil,
On a side note, I'm building along side a Cozy Mark IV builder, who happened to have a little extra epoxy. Since his resin doesn't react with the Aluminum or Primer and Top Coat that I used, I went ahead and epoxied the Snap Bushings in.

In other words, there's no getting them out!

Thanks any way, though!

-Andrew
Click to expand...
 
Phil,

I do not understand your thought.

I mean the snap bushings must go around the cable at some point.

And to do that the cable end must be put thru the snap bushing?

So no matter where the snap bushing is located this scenario will have to be delt with.


Granted i'm not at that step, nor do I even have the cables in my possesion, so maybe I'll understand better when I get those cables in my garage.

-Andrew
 
.... if the bushing is installed in the hole, the bushing can't be deformed like an egg.

.... without deforming the bushing the spoon shape on the rudder cable ends won't fit through the bushing.

They must to be removed to get them over the cable-ends and onto the cable. There's no other way around it.
 
Ahhh, okay! Now I'm with you!

Thank you very much!!

I'll do, as you've suggested.

I'll get those bushings out! (without damaging the metal, of course)
 
Since they're epoxied into the hole, you can apply some local heat from a heat gun. That will soften the epoxy to the TG point and you will be able to pull them out.

Glad I said something now or you'd be really upset later on when you are laying on your belly and trying to get them out.
 
Phil,

You're an awesome person, for thinking beyond what my mind had yet to even comprehend!

Thank you again!

-Andrew
 
I am far from awesome. But there are a few mistakes I wouldn't repeat if I were building another RV-10. I will let you buy me a Spotted Cow at Oshkosh though. :)
 
There is no need to set those bushings in any type of adhesive or epoxy,,,,and Phil is right that they will have to come out to get the cable ends through. I just ran my rudder cables last week and had to pop all mine out also.:eek:
 
You must log in or register to reply here.
Back
Top