How Beech Did Corners, Primer

[StuBob]

As a new (returning) builder, I've wondered about a few things that seem pretty ill-defined. Things like, how rounded to skin corners need to be? How broke (broken?) do skin edges need to be? And, of course, what to prime, if anything?

Turns out I have a source for all of those answers, or at least insight into how certain Wichita pros did it in 1970: my V35B Bonanza. So, off to the hangar I went.......

First, the corners. This is the front of the right-sided cowling. It's a little beat up, but it's 45 years old:

But that isn't where they crack. This is where they crack, at the first hinge rivet:


Then there's the lap joints. I don't see that any of them are broke (breaked?). But the skins are also much thicker than RV skins. My finger is there for scale. Looking closely, I suspect a lot of these corners were done by hand.


Some corners aren't radiused at all, but I've never heard of one cracking:


As an aside, I wonder how they got to the shop head on this one:


And my own entries into Primer Wars:


Here, notice the only things primed are the ruddervator mixer, which I think is steel, and the doublers behind the antennas, which were added on at some later date:


Not to say I'm not priming anything; just making conversation.

Happy New Year, VAF!

[N804RV]

Thanks!

[rightrudder]

Wow, those are massive castings for the mixer! Thanks for sharing the pics.

[aerhed]

I thought the mixers were magnesium. I've had to rebuild about 7 gear up bonanzas. The chin area up front usually has a bunch of pieces of aluminum shims stuffed in wherever. Wichita work ain't all that, that's for sure.

[mmass]

I work on Kingairs, Learjet 45 and citation bravos and everything is primed inside! When I get started I will paint a light coat of primer on everything.

[skylor]

Originally Posted by mmass

I work on Kingairs, Learjet 45 and citation bravos and everything is primed inside! When I get started I will paint a light coat of primer on everything.

Later model A36 Bo's are 100% primed with chromate primer inside. Also, I believe factory replacement parts (bulkheads, for example) come primed. I figure there must be a reason why they started priming parts on their later aircraft.

Skylor

[rv7charlie]

Originally Posted by skylor

Later model A36 Bo's are 100% primed with chromate primer inside. Also, I believe factory replacement parts (bulkheads, for example) come primed. I figure there must be a reason why they started priming parts on their later aircraft.

Skylor

Sure there is: Marketing. :-)

Seriously, it's more likely that they've seen *some* of their products with corrosion issues, if operated consistently in more corrosion-prone environments. Since they can't predict which planes will end up in those environments, and it would be more difficult to pick & choose on a production line anyway, they probably have made the decision to just do 'em all.

If I lived on the Florida coast, I might be more prone to priming everything, but I don't live there & don't expect my plane to spend a lot of time there. So the ribs/bulkheads got alodined and the faying surface areas got conversion coating type primer, and the interior of closed-up stuff like the tail got a mist of Boelube spray.

Charlie

[Charles in SC]

I had a 1970 V35 for several years. Mine was primed inside. Something kind of neat to look at are the milled panels in some of the larger Beechcraft.