Arming the floats on the S-92 is a very handicapped procedure. Vy is 80 kts, Arming of floats is Max speed 80 kts..so there is an airspeed limitation to this. If you arm the floats Above 80 kts, you will gett a yellow caution visible all the way to the back seating row 10m behind you.
Best autorotation speed is 80-100kts. ARA`s are done >80kts. You see, the limitation is set to low, and will easily be forgotten in a stressfull situation like this. Seen many times in the sim that it is forgotten because you don`t want a yellow caution in your face.
Understand the impact was quite hard and the fuel tanks came of?