Firstly, if the aircraft really was tumbling, don't you think it's remarkable that it struck the roof of The Clutha in a perfectly upright, wings level attitude?
Secondly, if the aircraft was, as it's last radio transmission suggested, simply transiting back to base, I don't really think the fenestron drive failure would result in an instant forced landing into a very 'hostile' area. Nor can I imagine any plausible fenestron control failure in forward flight that would trigger an immediate auto into the City centre.
Is there any suggestion the aircraft was at low speed/hover immediately prior to the accident?
Having said all that, I don't fly the 135, but I presume the tail fin has an aerofoil profile for a reason?
Not too sure I really buy the fuel starvation theory either? Though it's difficult to rule out contamination.
There are more prosaic reasons for rapid/unexpected total power loss.
All IMVHO obviously!
Last edited by Tandemrotor; 15th Jan 2014 at 07:33.