I've been refused my group 3 endorsment, where a large part of the practical experience was gained with my existing B1.2 licence (lots of tasks are common to the B1.2 and B2) because I was not "supervised", so I don't think FAA experience gained the same way would make it work. The point is, regulation and AMCs as they are written are almost impossible to meet, or, I'd rather think, made to protect the bosses of the avionic shops , so they, and only them, can have a licence, or the person they choose to grant one, for instance if they sell their business when they retire. And also, this helps to keep the wages of the employees low, as they can not go away and work on their own., and also helps them to control competition ...(no other shop can open, without a licenced person...). Keeping margins high, seems to be the priority, rather than safety, reason why lots of small flying clubs use aged avionics, and can not upgrade their planes with modern stuff.
