jugofpropwash: Although fuel contam is a very very small possibility (why didnt it contaminate the engines much earlier just after receiving the dirty fuel?), once contam fuel gets thru the filters, be it one or two tanks, the time between both flaming out would be seconds...
EC135's dont worry about bird strike from an intake perspective. The engine intakes are well screened inside the Dog House surrounding the MGB frame. Of course bird strike can and does incapacitiate in other ways: through windscreens, into tail rotors etc.
JTobias: I though about pilot incapacity too...for a short while. Even if the pilot "lost control" of his ability to fly the a/c, the rotors would have continued at nominal Nr until impact and the rotors would have disintegrated. This appears not to be the case with these rotors.
Sven 62: When you flare at the bottom of your auto (even in this case) the Nr increases, not decreases. So assuming he misidentifies the landing surface and flares harder to "gain height", the Nr will rise. He may well then drop further before landing, but the rotors will still retain enough momentum to disintegrate on impact with the back of the cab/other objects.
Does any Mode S tracker device show the a/c's speed seconds before it dissappears off screen? I can't determine if he was in a hover or cruising when it all went wrong?
If I was in a hover and the wheel came off (MGB slowed) causing the Nr to decay, I would instinctively push hard fwd cyclic and at the same time dump the lever. IF...and a big big ..IF the Nr had then drooped below its mimimum recoverable, then my descent would speed up rapidly and as SASless insinuated earlier when the MRGB slows, it drags the FPT's down with it, this would cause the Compressors to stall causing misfires/banging etc as Nr drags Ng down. I would then be in a zero spd EOL situation and at the bottom, have little or no Nr to arrest the descent with lever..
The latest reports are suggesting the investigating team are not expecting to recover debris away from the crash scene. To me that means there was a catastrophic failure somewhere along the common drive train between and including engine(s) and MGB.