Originally Posted by backpacker
Technically you only need an M-1 visa for a full-time course
I phrased my response the way I did because what is technically possible is irrelevant to the TSA who police flight training and have their own rules independant of US immigration law.
You need an M-1 visa to train for a standalone FAA PPL in the USA, because the TSA say so. You won't find it in US law, because it is an administrative rule, not law.