Can someone explain why you'd need to autorotate in a twin-engine aircraft? After all, the 757 that I took from LGW to EWR the other day doesn't have an official two-engine-out mode.
Of course there have been all-engine losses due to fuel tanks inadvertently becoming filled with air, or trying to make the RB.211s breathe volcano dust... but why are helos particularly susceptible?
On the VRS issue, to clarify - all helos are susceptible and it can be serious, but the worst case is that the helo sinks - pilot pours on pitch and power - sink gets worse - pilot says B***er, it's VRS, pushes collective fwd, flies out of vortex.
In the Marana crash, VRS struck first on one side which made the aircraft roll, not sink. Pilot instinctively reacted with opposite stick, but more power/pitch makes VRS worse, so the controls were effectively reversed.
Tactics and training have been changed to avoid VRS - the approach to the landing zone is fast, low, quiet and exploits the fact that the V-22 comes to a rapid screeching halt when the nacelles go vertical. The result is a short slow vertical descent rather than a long descent where the pilot wants to go fast to speed transit through a vulnerable zone.