Accident investigations results from the US Air Boeing 737 accident at Pittsburg, PA; a similar accident at Colorado Springs, CO, and several near-upsets involving Boeing 737's have suggested that the cause may be a sudden, uncommanded, full deflection of the rudder which causes the aircraft to becomeuncontrollable. 

Suggested remedies have included:

1) Redesign of the rudder to a two panel configuration so that full deflection of either panel could not provide enough control input to cause the aircraft to go out of control

2) Redesign of the rudder Power Control Unit to preclude full-scale rudder deflection at a certain critical airspeed and flap configurations

3) Modification of the Operators (Pilot's) Flight Manual to avoid changing configuration or operating in certain critical airspeed regimes

a) Which of these suggestions would be most effective and reliable IF the Boeing 737were still in the Design phase of its life cycle?

b) What issues might limit the effectiveness/desirability of this approach as a total solution?