"Anyone more recent on the Q400 has an idea of what rotational forces there are when applying max power from a trimmed idle position?"
After doing many real missed approaches in the Q400 I can say it does pitch up considerably and takes a fair bit of stick forward pressure to maintain the GA attitude.
"One more question related to this article: "All Q400 take-offs have to be brakes-off, rolling start." No explanation is given as to why, do any Q400 drivers know why this is the case?"
Engine limitations.
"I had assumed that the stick is totally free after a normal and uninterrupted push, but I don't know. So therefore it was specifically the time that the pusher took to release the force, that I was referring to, based on my assumption. On some jet transports it was released as soon as the push completed and the vertical flow on the veins returned to an acceptable figure."
There is no time limit, as long as the Stall Protection Modules detect the stall (• Angle of attack
• Flap position
• Mach number
• Power lever angle
• Condition lever angle
• Icing status) the stick pusher will activate.
In trying circumstances; bad weather, icing, low time, intercepting LLZ, both heads down looking at the FMS to confirm all is OK, it is very possible that the pilot did not immediately recognise that a Stick Push was occuring and his first reaction may have been to increase power to increase the airspeed and commence a missed approach.
An interesting point to consider; with INC REF ON (as you select in icing conditions), the speed that the Stick Pusher activates is increased by 20 knots, regardless of whether or not the increase is needed. In other words, if you forget to turn INC REF ON to OFF when you are out of icing conditions, the Stick Pusher will still activate at the higher speed, even though the extra 20 knots is not required.
I would hate to think that the upset caused by the Stick Pusher possibly activating 20 knots too early may have set off this disaster.