Corrosion within the laminate

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perossichi
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Re: Corrosion within the laminate

Post by perossichi »

This thread is paranoia inducing!

Checked my 2002, screws don’t look rusted or corroded, no sign of blistering, passed tapping test.I must be lucky.

Btw, sometime back there was a thread about small “poxes” or tiny raised bumps in a regular pattern on some diamond wings. I had a little of that on my right wing and top of horizontal stabilizer. With some polishing and perhaps, prolonged hot and dry conditions this has mostly gone away.
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Re: Corrosion within the laminate

Post by astaib »

Hi,

On the IPC, the screws that we are talking about look upside down? Or it is me?

I just ordered 12 screws DIN965 M3x12 A2, I hope that they will fir to replace my rusted ones.

Thanks.

Arnaud.
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Re: Corrosion within the laminate

Post by Steve »

Arnaud:

Looking at the photo you show, I don't think that you can replace the screws without pulling the wing (at least a few inches). I thought that the screws went into nut plates, so they could be removed without internal access. The diagram and your photo show that the screws have washers and nuts, so you would need access to the inside to replace them.

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Re: Corrosion within the laminate

Post by Rick »

I thought the 3 wing screws went into a nut plate, too. I wonder if they changed this design after 2001? Either way, though, I agree with Arnaud - the screws look upside down in the IPC drawing. Clearly, the screw heads should be on the outside of the wing, not the nuts!
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Re: Corrosion within the laminate

Post by astaib »

Steve wrote: Fri Sep 25, 2020 1:28 pm Arnaud:

Looking at the photo you show, I don't think that you can replace the screws without pulling the wing (at least a few inches). I thought that the screws went into nut plates, so they could be removed without internal access. The diagram and your photo show that the screws have washers and nuts, so you would need access to the inside to replace them.

Steve
Hi Steve,

From the drawing I agree that it is not possible to change without pulling out the wings, but from the picture (this is the wing of my plane), it looks that I can change the screws easily, don't you think? I think that the collar "inside" the wing are fixed to the plate.

i hope that I get the right screws, because M3 seems small to me.

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Re: Corrosion within the laminate

Post by astaib »

Rick wrote: Fri Sep 25, 2020 1:37 pm I thought the 3 wing screws went into a nut plate, too. I wonder if they changed this design after 2001? Either way, though, I agree with Arnaud - the screws look upside down in the IPC drawing. Clearly, the screw heads should be on the outside of the wing, not the nuts!
Hi Rick,

From the picture of my wing and from my observation (I see the head of the screws under the t-profil rubber), the screws and IPC are upsdie down!

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Re: Corrosion within the laminate

Post by Steve »

Arnaud:

Although the resolution is not great, I believe that your picture shows standard nuts, not nutplates. Nutplates would be riveted to the underlying metal strap, and be thinner in outside diameter than the nuts in your photo. The other thing which speaks against nut plates is that they would only be used when typical disassembly of the part in question would not allow or require access to the back side. Replacing or servicing the conduit would require removal of the wing anyway. I don't think that Diamond anticipated the need to replace the screws only for corrosion control (or they would have used a better design). I agree that the diagram in the IPC is incorrect as to orientation.

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Re: Corrosion within the laminate

Post by astaib »

Hi!

Because it is Sunday and because it is raining, I decided to change all these screws because I ordered 15 of them.

First I’m surprised because the M3 screws listed in the IPC are too small (as I was expecting ...).

But because I was there I inspected closely and removed the film that was covering them.

First I tell you that it is a bad idea to have film covering these screws, because humidity was there. Then I tried to removed the screws: those on the intrados are impossible to remove (because of rust I guess), those on the extrados are moving (no appearance of rust) but the nuts seem not to be attached on the plate, so the screws are impossible to remove without removing the wings.

BUT, what I don’t like is that because I looked from very close with a powerful led light, I see something that might be a sign of blistering. But to be honest it looks like bubbling of the painting more that the laminate.
Here is a picture (cannot make a better one), what do you think:
71E50245-1F0F-4BD0-935C-663325C1C1EB.jpeg
I made a tap test, indeed it is not making the same noise because it is closer to the edge, and it’s not sounding like “empty box”.

Here is a picture of the other intrados, screws are rusted but no sign of blistering:
CB17D4BB-2C05-4035-A495-E6B6BD1F9BAB.jpeg
The aspect is bad because painting is worn at this place, previous owner has put silicone to hold the t-profile, and to remove the silicone, he removed the painting too...

All in all, I don’t know what to do, because I don’t like to let rusting screws in place. What do you recommend?
Is it more easy to only remove the wings for some centimeter in order to cut the rusting screws, replace them and inspect the suspicion of delamination.

Arnaud.
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Re: Corrosion within the laminate

Post by Rich »

Arnaud, There is a small gap between the wing and its root and you might be able to examine the inside portion for corrosion. with an endoscope. If there isn't a problem inside the wing, I would try using polishing compound, by hand (finger, actually) on a rag and remove the surface rust. Use a plastic toothpick and do the same in the Philips grooves. These screws are not holding major structures in place and may be OK.

I thought for about 2 seconds about putting some glider tape over these but realized it would only serve to trap moisture in there (an little-known law of the universe). Instead I make sure when I wax the airplane these get included. Something like clear nail polish might be a way to go, as well.
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Re: Corrosion within the laminate

Post by astaib »

Rich wrote: Sun Sep 27, 2020 2:39 pm Arnaud, There is a small gap between the wing and its root and you might be able to examine the inside portion for corrosion. with an endoscope. If there isn't a problem inside the wing, I would try using polishing compound, by hand (finger, actually) on a rag and remove the surface rust. Use a plastic toothpick and do the same in the Philips grooves. These screws are not holding major structures in place and may be OK.

I thought for about 2 seconds about putting some glider tape over these but realized it would only serve to trap moisture in there (an little-known law of the universe). Instead I make sure when I wax the airplane these get included. Something like clear nail polish might be a way to go, as well.
Hi Rich,

Thank you, so I will remove the T profile and inspect with an endoscope. But from what I understood, the suspected corrosion of this problem is inside the laminate on the metallic part ? Impossible to see it, isn’t it?

Arnaud.
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