Mainly intergranular corrosion. I learned that, except for the Alon
models, all the Ercoupe spars were made in one batch in the 1940s,
whichever year it was that most 'coupes were made (1947?)
Big snip
Thanks for that. The intergranular corrosion issue is a huge one, and not
just for Ercoupes. Cherokee spars have experienced it, too. It's fatal,
and expensive to fix. Service bulletin 1006 addresses it, and performance
should be a mandatory part of any pre-buy inspection. If it hasn't been
done, either do it (it's not hard) or pass on the plane.
Luckily, intergranular corrosion is fairly easy to spot, once it's
started -- so it's easy to rule out a plane that's got it. Unfortunately,
it can be lurking inside any spar, unseen.
However on the bright side, last year at OshKosh someone announced
that he had completed an STC to bring the sport pilot eligible
Ercoupe's gross weight up to the sport pilot maximum -- a 60lb
increase.
Yep, that's another reason we passed on the LSA Ercoupes. I can tell you
right now that if you see two full-grown men flying in a '46 model, that
aircraft is over gross. How in the heck any CFI gives instruction in those
models is beyond me -- they must just look the other way at the FARs and go
fly.
However I do sort of agree with your insurance company on training,
they are very easy and fun to fly but some things (like xwind
handling) are different enough that someone trained on a conventional
airplane has to unlearn a few things, or at least do some things that
feel very uncomfortable at first (taking off in a left crosswind is,
umm, fun). It would probably be easier without years of conventional
two-control airplane experience under your belt 
.
I spent some quality time with our insurance policy yesterday, and was
delighted to discover that the company had listed ME as "Honeck, Sr" and my
son as "Honeck, Jr." Since *I* am "Jr.", and my son is "III", I was
mis-reading my insurance requirements to show that I needed a bunch of dual.
I don't.
So, today we're off to fly the 'Coupe!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
Ercoupe N94856
www.AlexisParkInn.com
"Your Aviation Destination"