On Apr 20, 4:44*pm, wrote:

Bad idea - The Blanik wing skin alloy is the same soviet era material
used on early MIG's. Not even close to 2024, probably stronger than
7075-T6, and anodized, not clad.

I'd like to see some data on that, can you point me towards a citation
or resource?

Regardless, it's easy enough to test; just snip out a coupon and pull
it to failure. I've done similar tests many times and often posted the
results to YouTube. There's a broken Blanik between my work and home;
I might try and get a pull coupon off of it to compare with 7075-T6,
2024-T3, and 6061-T6.

Assuming you can identify the major alloying elements of the factory
skins, how will you determine the aging tempering process used, and
show compliance/conformance with the design material properties as
required by the FAR's? *

Once you've demonstrated that the strength of the replacement is equal
or better that of the original material, most of the other stuff is
pretty much irrelevant. The alloying and temper will mostly affect the
yield and ultimate strength respectively, and you would already have
demonstrated that.

Of course if the replacement alloy is drastically different than the
original there could possibly be a galvanic issue between the original
and replacement material. But in my direct experience, that's more an
issue of taking appropriate anti-corrosion measures and monitoring the
repair in subsequent inspections.

Anyhow, what you really need to do is demonstrate to an A&P or IA's
satisfaction that the substitute material is of equal or better
strength than the original, to the degree that they would feel
comfortable executing the repair and signing it off. I've seen a few
Blaniks with locally-fabricated repair panels, so I know that such a
thing is not unheard-of.

Thanks, Bob K.