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Old 18th Jul 2011, 09:12
  #428 (permalink)  
rudderrudderrat
 
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Hi takata,

It seems better to have in this case a pitch Alternate rather than direct, certainly because autotrim (inop in direct law) will permanently deal with fuel transfers (the pitch law is mostly based on CG computation by fuel computers). It will also damper pitch sensitivity if CG is aft, while roll axis should be trimmed by rudder and the aircraft is supposed to fly in straight line hands off.
Is the reason that AB FBW don't have the option for the pilots to deliberately select Direct Law (unlike B777) because the allowed CofG can be so far aft and the subsequent handling characteristics?

I agree that rudder should be used to trim out any roll tendency - maybe if the aircraft had been perfectly in trim at the time of AP disconnect, then the PF could have just left the controls centred and continued at FL 350.
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