PPRuNe Forums - View Single Post - AF 447 Thread No. 9
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Old 13th Aug 2012, 01:22
  #1224 (permalink)  
thermostat
 
Join Date: Mar 2000
Location: canada
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Auto Trim

Seems to me that some folks don't understand the "auto trim" concept.
The elevator and stab must be faired (in a straight line) in order to remove the load (forces) on the control column/stick.
If the stick/wheel is moved back, the elevator moves up and is no longer faired with the stab. The pilot has to trim nose up (leading edge of the stab moves down) so as to align to two surfaces and remove unwanted pressure.
Instead of the pilot having to manually move the trim wheel, auto trim simply does it for him/her. Holding back pressure on the wheel/stick will cause the auto trim to move (trim) the stab until the two surfaces are aligned (faired).
That's what happened in the case of 447, The auto trim did exactly as it was supposed to. It trimmed the stab to fair with the up elevator. It's a beautiful system that reduces the workload on the pilot. If they wanted to recover from the stall condition, all they had to do is push forward a bit on the SS moving the elevator down and the auto trim would have dutifully trimmed nose down to the required angle. End of stall. Please stop blaming the auto trim for doing it's job.
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