Older kit - corrosion?

Hello VAF!

I recently bought a tail kit that a builder had purchased way back in 2002, and essentially never started. Most of the metal was still covered in the blue plastic, and when removed looked great. But there were 3 ribs for the VS that were previously devinyled by him. These looked fairly dull, and I am concerned about corrosion. See below, this is the worst example:



My plan was going to be:
-Use a maroon scotch brite pad to buff out these darker spots, then clean and prime to prevent further corrosion.

Does this sound reasonable?

samiamPA said:

Hello VAF!

I recently bought a tail kit that a builder had purchased way back in 2002, and essentially never started. Most of the metal was still covered in the blue plastic, and when removed looked great. But there were 3 ribs for the VS that were previously devinyled by him. These looked fairly dull, and I am concerned about corrosion. See below, this is the worst example:

My plan was going to be:
-Use a maroon scotch brite pad to buff out these darker spots, then clean and prime to prevent further corrosion.

Does this sound reasonable?

Click to expand...

Yes...that doesn't look too bad to me.

Most of the formed parts that come from the factory have that dule appearance. Ribs don't typically have vinyl wrap on them.

Yep, looks normal to me. Still building a kit from 2002ish. Prime or not - your choice. Actually, if I was to do again and wanted corrosion protection. Alodine tank dip is pretty easy, fast for protection.

Welcome

Welcome Sam.
Your plan is good. I did the same. My empennage was several years old too.
Order the Horizontal Stab Service Bulletin. You might as well install it now.
Check out my blog, "empennage" page. Scroll to the bottom. I tried to document the assembly of the HS when I rebuilt it.

I dont see any corrosion on that part. Corrosion on aluminum looks normally like a white powder residue on the surface. Just scuff it with a scotchbrite pad and prime.
Regards
Arie

Thanks to everyone for letting me tap into your collective experience, and dealing with my newbie questions!

Arie said:

I dont see any corrosion on that part. Corrosion on aluminum looks normally like a white powder residue on the surface. Just scuff it with a scotchbrite pad and prime.
Regards
Arie

Click to expand...

This is what I thought--I wasn't sure about the brownish discoloration. Just trying to be as safe as possible though and learn from those with experience.

Not Corrosion

Most parts with formed flanges (ribs, bulkheads) are formed in the soft or 'O' temper condition. Then they are heat treated to the final such as 2024-T3. Your rib looks like normal heat treat coloring. If you are not going to primer it, leave it alone. The alclad surface isn't very thick and if you go heavy on the scotchbrite, you can reduced the alclad thickness and thus the corrosion resistance.