If the engine fails, the heli can "auto-gyrate". Meaning the
rotor blades which do not have power from the engines are now free
to rotate of their own accord. By doing so, they create drag on the
heli, thus slowing down the descent. Like a parachute for the heli.
THIS IS THE THEORY...
IN PRACTICE...
if the heli is damaged, or weight is distributed unevenly, the heli
may also roll to the side or point tail or nose down, thus limiting
the effectiveness of the auto gyration. Meaning... you will meet
Mother Earth pretty hard and not necessarily with those parts of
the heli that were supposed to do so (e.g. the skids or landing
gear).
IN WHICH CASE....
The pilots' seats are designed structurally to withstand 20+g of
crash energy, meaning to say, that upon impact, they will not be
crushed even if a force equal to 4000 pounds were impacting on it.
The pax seats are designed to a slightly lesser crash impact level
(can't remember the reasons... probably saving the more expensive
pilot and reducing weight of the heli are the key things).
