Cracks in E-903 Tip Rib during Dimpling and riveting - Seeking Advice

[Scyboz Michel]

Hello fellow forum members,

I hope this message finds you well. I am currently working on my RV14 project, specifically on the E-903 Tip Rib from the elevator. Unfortunately, I've encountered a concerning issue during the dimpling process.

When attempting to dimple the E-903 Tip Rib, I noticed cracks appearing. I've double-checked my tools, technique, and followed the instructions meticulously, but the problem persists. I am reaching out to the community to seek advice and guidance on how to address this issue effectively.

The flanges seem to be factory-bent, running on from the holes, which probably caused the crack

(See attached pics)

If anyone has faced a similar problem or has insights on how to prevent cracks during dimpling on this specific part, I would greatly appreciate your input. Additionally, if there are recommended modifications or alternative approaches that have proven successful, I am open to exploring those options.

Thank you in advance for your assistance. Your expertise and shared experiences are invaluable, and I look forward to your responses.

Best regards,

 

[deMan]

LCP?

I’m pretty sure E-903 is in the LCP list. Was yours laser cut or punched? If it’s laser cut, that’s your answer as to why it cracked.
If not, this will be an interesting thread.
-Lars

 

[Dr_Dave_MT]

Both E-903 and E-904 are on the LCP List Rev-7 although the first date of anomaly is different for each part.

 

[Scyboz Michel]

The empennage kit was dispatched by Van's on March 22, predating the LCP problem.

 

[PaulvS]

Hi Michel,
The dimples look elongated and possibly not evenly formed, although it is hard to see from the photo. Does the female dimple die have one side ground flat so that it can clear the flange adequately? Or possibly the squeezer is not sitting flat because of the narrow gap in the thin end of the rib.
Also, it looks like the blue vinyl is still on the skin. That should not cause the cracking problem, but it should be removed in case it has been left on?

 

[Scyboz Michel]

On the rib there is a kind of flute just in line with the drilling. This makes the dimple irregular and this makes aluminum more prone to cracking.


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[rvbuilder2002]

On the rib there is a kind of flute just in line with the drilling. This makes the dimple irregular and this makes aluminum more prone to cracking.


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What made the flute in the flange at the cracked dimple locations?
A standard kit part does not have flutes in it like shown in your photo.

 

[Bavafa]

What made the flute in the flange at the cracked dimple locations?
A standard kit part does not have flutes in it like shown in your photo.

And I would expect the flute to be for the entire flange and not just that short part to the drilled hole. From what it looks in the picture this does not look like a flute, perhaps other deformation?!?!?!?

 

[georgemohr]

Agree with all above, something is not right with that rib. There should be no flutes on a straight surface flange.

 

[Scyboz Michel]

Agree with all above, something is not right with that rib. There should be no flutes on a straight surface flange.

Yes totally agree. Both elevators Ribs E-903 have the same “flute”…
You can see it on the following picture:

 

[PaulvS]

It appears that the factory makes those dimples so the builder does not need to dimple them.

See this thread:
https://vansairforce.net/community/showthread.php?t=213310

And the picture of the part in the Van's store, showing the dimples:
https://store.vansaircraft.com/e-903-elevator-tip-rib-e-903.html

The problem though is that the factory "dimples" in your part do not look like they were formed normally and are elongated rather than round. So it is probably going to be best to contact Van's support and potentially replace the tip ribs.

Sometimes the plan instructions do not match the parts, otherwise there should be a note to say they are already dimpled.