Corrosion within the laminate

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Gary
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Re: Corrosion within the laminate

Post by Gary »

Kai wrote: I don't know on what this is based. Maybe that's the average time until the wings fall off :shock:

I will ask them again in a few weeks when I am there to get the annual done and report back.
The big question is when you should do the repair if corrosion develops. If it can be repaired relatively inexpensively early then it would make sense to do this. If the repair cost is about the same early or late then you should probably wait as long as possible to have it repaired. It would be good if some knowledgeable person could give some guidelines.
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Charles
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Re: Corrosion within the laminate

Post by Charles »

Based on the e-mail I got from Diamond about this and which I pasted in the first post of this thread, it seems that if you wait too long, the grounding strip might need to be replaced in its entirety, which would make this a much bigger repair than a localized buffing.

Still, it would be nice to know how long one can wait without risking having to replace the grounding strip.
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Gary
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Re: Corrosion within the laminate

Post by Gary »

Midwest Avtech in Peru Illinois (about 60 miles SW of Chicago) owns a 2003 DA40 used for pipeline patrol with about 6,000 hours. Their DA40 developed corrosion on the underside of both wings and made the repairs themselves using information supplied by Diamond. They are a Diamond Service Center and have been recommended by a couple of DA40 owners. If you have this problem and live in the vicinity you might consider giving them a call.
http://www.midwestavtech.com/services.htm
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Lance Murray
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Re: Corrosion within the laminate

Post by Lance Murray »

I just can't see how this strip can be corrosion proofed without removing it in it's entirety. If you only buff and protect the area that gets exposed then you have only partially treated the strip. The rest of the strip is still susceptible to corrosion. To do this properly one would need to replace the entire strip of metal otherwise we are just doing a band-aid fix until a later date when the corrosion will return.

I will be doing the band-aid fix myself under supervision. I will try to take pictures and write a report.
Gary wrote:
Kai wrote: I don't know on what this is based. Maybe that's the average time until the wings fall off :shock:

I will ask them again in a few weeks when I am there to get the annual done and report back.
The big question is when you should do the repair if corrosion develops. If it can be repaired relatively inexpensively early then it would make sense to do this. If the repair cost is about the same early or late then you should probably wait as long as possible to have it repaired. It would be good if some knowledgeable person could give some guidelines.
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Gary
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Re: Corrosion within the laminate

Post by Gary »

Lance Murray wrote:I just can't see how this strip can be corrosion proofed without removing it in it's entirety. If you only buff and protect the area that gets exposed then you have only partially treated the strip. The rest of the strip is still susceptible to corrosion. To do this properly one would need to replace the entire strip of metal otherwise we are just doing a band-aid fix until a later date when the corrosion will return.
I will be doing the band-aid fix myself under supervision. I will try to take pictures and write a report.
The shop I spoke with told me there is no way to corrosion proof the metal strip that is embedded in the composite. You just have to repair it when it corrodes.
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Re: Corrosion within the laminate

Post by Erik »

I am really surprised that Diamond used corroding materials in this hard to get to high cost to fix location. I believe that if they had used titanium hardware and bands for example, that it would be immune to this problem. I have 3 different titanium bikes and I can say it is a wonderful material for many reasons (corrosion proof, light like aluminum, strong like steel and more compliant/shock absorbent than either), not least of which is that it does not even need to be painted. You can sweat on it, ride it on salty roads and after a decade not even a hint of corrosion. You might say it is an expensive material, and it is, but for these small fixtures it would not require a great deal of material and cost for DAA to do this thing right - moving forward on new airplanes. Anyway the material is not too expensive to make bicycles and so why not airplanes? My watch by the way is has a titanium case and it only cost $100.
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Re: Corrosion within the laminate

Post by Charles »

I believe the conductive material used in the laminate is copper and that's the part that corrodes. I agree that the mechanical properties of titanium are far superior to those of copper but the material was most likely chosen for its electrical properties, not its mechanical properties. From that standpoint, copper, with about 20 times the conductivity of titanium, is far superior.

Gold is almost as good a conductor as copper and doesn't corrode though. :D
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Re: Corrosion within the laminate

Post by Erik »

Charles wrote:I believe the conductive material used in the laminate is copper and that's the part that corrodes. I agree that the mechanical properties of titanium are far superior to those of copper but the material was most likely chosen for its electrical properties, not its mechanical properties. From that standpoint, copper, with about 20 times the conductivity of titanium, is far superior.

Gold is almost as good a conductor as copper and doesn't corrode though. :D
Oh well re Ti - forgot why it was there for electrical conductivity, but yahoo re Au! Au indeed is a good conductor and not reactive.
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Jean
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Re: Corrosion within the laminate

Post by Jean »

Erik wrote:
Charles wrote:I believe the conductive material used in the laminate is copper and that's the part that corrodes. I agree that the mechanical properties of titanium are far superior to those of copper but the material was most likely chosen for its electrical properties, not its mechanical properties. From that standpoint, copper, with about 20 times the conductivity of titanium, is far superior.

Gold is almost as good a conductor as copper and doesn't corrode though. :D
Oh well re Ti - forgot why it was there for electrical conductivity, but yahoo re Au! Au indeed is a good conductor and not reactive.
Specific weights:
Au 19.3
Cu 8.9
Ti 4.5
Al 2.7
Why are so many planes made from Aluminium ?? :scratch:
40.446, G1000, KAP 140, Hartzell Metal
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Re: Corrosion within the laminate

Post by Erik »

I'll take Gold then.

Besides the specific weight there must be a strength to weight ratio when it comes building airplanes and Ti ranks very well. Steel rates surprisingly well which is why Steel is still amongst the favorable bicycle building materials, and AL is also pretty good although it takes relatively thicker structures when working with AL. Al also has a nasty habit of just fracturing and sudden failure when compared with Steel or Ti. But the metal in the Diamond wings is not structural as I was reminded it is only there for conductance. This makes me wonder - maybe they could somehow coat some metal like Copper with a non reactive but conductive metal like gold. Just a little bit. Go ahead and fire away and my silliness since I am not a chemist and I am sure it shows.
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