There are a couple of thoughts with that 767 ditching accident.
1 - the captain was clobbered in the head with the crash axe
2- the 767 with dual engine flameout (due to fuel starvation in this case), has a RAT (Ram Air Turbine) which drops out to provide hydraulic power to the primary flight controls. To maintain sufficent hydraulic power there is a mimimum airspeed that has to be maintained ( I cant remember what that is). There was the possibility that combined with a wack to the head, and the hijackers on the flight deck with the struggle, that the airspeed dropped below the minimum, causing a wing drop.