Wow...
Can you put some references to NTSB investigation?
Have the pilot/trainee survived - (AFAIK any aerobatics require the crew to be stripped to a parachute)?
It was several years ago (like 10 maybe), but over the space of 2 or 3 years in that particular industry there were at least 2 fatal mishaps from structural failures. Sorry, I don't have any links to news reports since it was so long ago. I vaguely remember that there were some ADs for beech bonanza wing spars that maybe should have applied to T-34s regarding wing spars, but maybe they didn't get done on the T-34s due to construction differences or something? In any case, there was a slew of finger pointing and insurance rates went up, and next thing you know they're just not advertising much any more. I contacted one outfit a year ago to see if they were hiring, and was told that they were low volume and due to liability issues they were doing corporate team building gigs, where they'd sell a package deal to a company and have a dozen or more people come out all at once for a day of flying.
Maybe Mouse could give you the real story since I think he's a lot closer to that business... This is just what I heard and pieced together from the news reports and hearing this and that over the last several years.
My Dad flew with one of the outfits using SF-260s before the mishaps, and he had a blast until he started puking. I don't think any of the outfits flying SF-260s ever had any mishaps but it wouldn't surprise me if they got caught up in the insurance rate increases anyhow.