We were discussing crashworthy strength on another thread. The piece of the building caused a sudden rotor stoppage, as if the rotor struck a big rock. Note how the transmission was ripped from the helo, because the old crash standards didn't require the strength to have the helo stay together in such a strike. In a way, the blades are stronger than the transmission mounts. The BO-105 family was designed to the old FAR 27 standards.
In a more crash worthy machine, the blades would have broken off, but the fuselage would have stayed unharmed, and the transmission would have stayed put, all to protect the cage the occupants are in.
When buying a helicopter, it is quite right to value this new strength (in at AB-139 and the S-92) as an improvement over previous designs.
Of course, helicomparitor has told you that window size is more important than the structural strength of the helicopter, and its crashworthiness!!!