re: the suggestions about HS moving in an uncontrolled way to initiate +/- pitch stresses to damage airframe.
1 How long does it take for the the screwjack in normal controlled rotation to move from neutral/level flight to its maximum up or down position ?
2 If there is failure in the screwjack system (e.g. hydraulics or mechanical integrity loss) is the HS free to flutter, perhaps in response to PF responses with ailerons to control AofA ?