Spiderweb cracking on the forward spar

avtrix · Post by **avtrix** » Mon Jun 12, 2006 2:26 pm

I wish I had a picture to show you all exactly what I'm referring to, but I don't at this point.

I'm wondering if anyone else has seen this phenomenon and what (if anything) you think I should do about it. It's so subtle that I didn't even notice it at first, but upon closer examination after attaching the tank-attach platenuts on the forward spar I noticed hairline cracks around nearly every rivet. They're in a "starburst" pattern and they appeared after squeezing the rivets - not during countersinking. I can see it best when shining a flashlight on them.

Is this just the anodizing or something more serious?

prestwich · Post by **prestwich** » Mon Jun 12, 2006 3:11 pm

I'd say it's the anodizing, which wouldn't be a problem structurally now, but which could hasten corrosion. I'm not priming anything, so I personally wouldn't worry about it if it were my airplane. (I'm going to use the ACF-50 instead.)

Anodizing is controlled corrosion, aka rust, aka oxidation. Aluminum oxide is about the hardest stuff on the planet. Hard means brittle. Aluminum, on the other hand, is pretty soft. So, I'd say you're seeing anodize cracking, not metal.

cjensen · Post by **cjensen** » Mon Jun 12, 2006 3:36 pm

Mine did the same thing. Don't worry about it, it's just the anodizing showing a little cracking. Like p-wich said, it's very brittle, and scratches off easily if your not careful too.

JohnR · Post by **JohnR** » Mon Jun 12, 2006 4:05 pm

I agree with the above. Mine did it also. I believe it is expected.