when any crash occurs, the "experts" are interviewed in the immediate aftermath of the crash, and they typically say, "It's too early to speculate on what caused this". Of course, what they mean is that it is the right time to speculate, but it is too early to know.
I mean, if you're going to speculate, you may as well do so. Might not be totally irrational to wait and see what the evidence is. The fact that the helicopter seems to have turned back suggests to me that perhaps there was some mechanical issue detected by the pilot. That's my speculation.