I think GG placed the limit per phase, which seems to be 6 hrs available. Based on those values, D4Y1 could fly 690 nautical miles in 3 hours cruise speed, which is 17.5 hexes. I don't remember it's range right now though. But based on that, it should be able to strike further than 8 hexes.
BTW, I just had US CV strike going out to 8 hexes...so it seems that Allied limit is not 7 hexes but 8 too. Unless I misscounted, of course, but I am pretty sure it was 8 hexes.
"To meaningless French Idealism, Liberty, Fraternity and Equality...we answer with German Realism, Infantry, Cavalry and Artillery" -Prince von Bülov, 1870-