I used to instruct on the Gazelle, in the mid 1980s. No-one had ever heard of "Fenestron Stall" despite the aircraft having been in service for quite some years.
I went away on a different job for a year and then went back to refresh on it, at the same base, with CFS and an instructor I knew of old. No-one told me that "Fenestron Stall" had by then then been invented/discovered and handling restrictions imposed. on the first flight I tried to do what I thought was a normal pre-takeoff lookout turn (must have done thousands before in exactly the same conditions) and was immediately told off because I'd dared to put the wind on the "wrong" side.