Unibit Screw-up

[Bugsy]

Drilling conduit holes in the wings. Had a Unibit drill go stupid on me. The drill twisted the metal and tore 2 cracks on the left and right of this hole.

The rivet holes are there because I decided to put a doubler plate on both sides.

1st I stop drilled the cracks.

Then deburred the rough edges.

Then made a doubler plate on both side of this mess.

Yes the finished side of the rivet is on the inspection plate side.

Question to the experts on this forum. Have I done a good job fixing up this area? It seems stronger than before. I cant image anything else to beef it up.

 

[Rupester]

Looks good. I would be very comfortable with that fix.

 

[lorne green]

I'm no A&P but

I'm sorry that the unibit had a mine of it's own! The repair looks professional, well done. For drilling out the rest of your conduit hole let me suggest that you increase the drill RPM to maximum.
I see you prime with SEM/Napa 2770. Quick and Durable.

 

[Captain Avgas]

Question to the experts on this forum. Have I done a good job fixing up this area? It seems stronger than before. I cant image anything else to beef it up.

Being "stronger than before" is often a very bad thing. The stiffer reinforcement element can result in very high stress concentrations in the single layer of material around the perimeter of the doubler. That could result in long term fatigue problems. In your case you seem to have a doubler plate on both sides of the repair. And the rivet spacing may not be optimum.

Also, in looking at the holes you have drilled for the repair rivets I note that they are all BADLY elongated...and you seem to have driven the drill chuck into the metal and badly damaged it as the drill broke through. None of this is good in such a critical location.

These type of repairs cannot be done on an "intuitive" basis by builders with no engineering background. I think you should have asked Vans for their advice. At the very least you should be adopting principles as laid down in AC43.13 (AIRCRAFT INSPECTION REPAIR & ALTERATIONS).

I recommend replacing the rib if it is at all possible to gain access for rivetting at this stage. I see you have a QB and sometimes QB builders are less keen to replace elements because they did not instal them in the first place so they lack knowledge. But it may be no big deal to replace that rib.

At any rate, don't take any notice of anyone on this website (including me!). Send the photos to Vans and get advice you KNOW you can rely on. You should specifically indicate that you have two doubler plates and you also have elongated holes.

 

[newtech]

Being "stronger than before" is often a very bad thing. The stiffer reinforcement element can result in very high stress concentrations in the single layer of material [snip] These type of repairs cannot be done on an "intuitive" basis by builders with no engineering background.

Everything you say is very true but this is a little harsh, for what is really just a cosmetic repair, don't you think?

I think you should have asked Vans for their advice. At the very least you should be adopting principles as laid down in AC43.13 (AIRCRAFT INSPECTION REPAIR & ALTERATIONS).

Good suggestion, can't argue with this. I think the repair as illustrated is within the spirit of AC43.13 .

I recommend replacing the rib if it is at all possible to gain access for rivetting at this stage. I see you have a QB and sometimes QB builders are less keen to replace elements because they did not instal them in the first place so they lack knowledge. But it may be no big deal to replace that rib.

The fix isn't structural, why run the risk of doing more damage by replacing the entire rib? For peace of mind go ahead and email Van's with your photos and let us know what they say.

 

[Captain Avgas]

Everything you say is very true but this is a little harsh, for what is really just a cosmetic repair, don't you think?

I'm not being harsh at all. I'm just stating some facts so that there is no misconception here.

Vans RVs use a monocoque construction. The wing skins are load bearing. And the wing ribs transmit loads from the skins to the front and rear spars.

Thus the wing ribs are structural....and therefore any repairs to the wing ribs are structural repairs.

In fact if truth be known there is NOTHING in an RV wing that is not structural in the strictest sense of the word (except PERHAPS the composite wing tips...but even that could be argued).

To suggest that any repair to a wing rib on any RV is "cosmetic" is promoting a very dangerous myth that might lead other builders to adopt unsafe building practices.

 

[jsharkey]

Drilling conduit holes in the wings. Had a Unibit drill go stupid on me. The drill twisted the metal and tore 2 cracks on the left and right of this hole.

The rivet holes are there because I decided to put a doubler plate on both sides.

1st I stop drilled the cracks.

Then deburred the rough edges.

Then made a doubler plate on both side of this mess.

Yes the finished side of the rivet is on the inspection plate side.

Question to the experts on this forum. Have I done a good job fixing up this area? It seems stronger than before. I cant image anything else to beef it up.

It's worth checking with Van's but it looks fine - "Clyde Built" as they say from the ship building area where I come from.

Jim Sharkey

 

[Bugsy]

Vans said Repair is Good to Go

Just got off the phone with Bruce at Vans. He took a look and said my repair was overkill, I could have used pop rivets and been fine. He liked the repair, which makes me feel a whole lot better.

The location of the conduit hole was selected because it isnt a critical structural point.

I do appreciate all the input, made me make the call to vans and also think through these issues when the pop up. I appreciate the banter.

Sure is nice to know that Vans designed an aircraft that is so well thought out.