Back during my college days, we had a professor who talked about this BAC 111 deep stall crash (I'm guessing it was an Aero Stability and Control class but it's been ~45 years).
Anyway, after describing the crash deep stall characteristics that caused it, he stated there had been another flight test crash of a T-tail designed aircraft where they were simulating an electrical power failure that disabled the stick-pusher and inadvertently got into a deep stall. He even elaborated that they tried various tricks (that had been brainstormed after the subject crash) in an effort to get out of the deep stall, but to no avail. But looking on the internet - while I can find other deep stall crashes of T-tail aircraft - I can't find one that fits his description of happening during flight testing.
Anyone know what he may have been talking about?