Can anyone post me a ref. for that? I've come across with this somewhere but can not find it again..
I just asked myself the same question. From this
post I gather the 10 minutes are, more or less, an industry standard.
Publishing a maximum acceleration altitude in the AFM might be a requirement according to CS 25.1585, although I couldn't find further specifications in the relevant AMCs. Maximum TOGA thrust time must be published according to CS 25.1583 (b) (1) and 25.1521 (c) (1) (ii).
I wonder if there is indeed any provision that prescribes 10 minutes of TOGA thrust to be available. I guess CS-E might even require demonstrations of longer periods at TOGA thrust which are then factored with safety margins and end up as 10 minutes in the AFMs, but I'm really guessing here.
Like Brotti, I would appreciate a little help with references.