On Friday, January 15, 2016 at 4:51:30 PM UTC-5, wrote:
...how the Eta glider used for certification broke up some years ago:
when getting out of a spin with full ballast in one wing, the other empty,
the fuselage couldn't resist the torsional load and failed.

I was briefed that the Eta accident was caused by not recognizing
that the spin had degenerated to spiral dive, followed by incorrect
recovery from spiral dive. Was I briefed incorrectly (by a factory
test pilot, briefing me on spin recovery in another make/model)?

Thanks,
Best Regards, Dave