Yeah well pilot stuff aside the major problem will be the shaft breaking would probably whip around and cut the housing which actually holds up the front of the engine.
If that happened the front of the engine would drop and you can forget about FCU this-and-that as all the angles would change to the FCU arms and the Tail Rotor short shaft would probably also separate (that would whip around a fair bit too, good bye tail rotor control rod, boom would probably stay on).
Youd have a lot more problems very quickly.
Id say its not in the flight manual for the same reason blades coming off arent in there .
(Youd probably want to get out before any of this happened)