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Old 9th Apr 2016, 11:31
  #1155 (permalink)  
Sciolistes
 
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Originally Posted by portmanteau
according to 737flightsim.com total stab travel is - 0.2 to +16.9 trim units and 1 degree of stab travel = 1 trim unit. Full scale travel thus = 17.1 units or degrees. Stab is neutral at 4 trim units.
OK, so the flight simmers reckon that 1 unit = 1 degree. Hmmm.

Just running with that, how is it possible to get -5 units of trim then? Did they mean the crew changed the trim by 5 units nose down? I guess that must be it.

So, if the flaps were up, which the FR24 speed profile certainly suggests, then I doubt they would go from typical approach trim values with F30 (say about 7 units) to something 5 units less because the trimmer will stop at just short of 4 units. They would have had to pull the handle and trim manually.

If the flaps were still extended, then they could trim to a little more than 0 units.

In either case, with zero trim with the flaps extended or 4 units of trim with the flaps up, a level attitude still could be still be maintained with effort. It is difficult for me to understand how such a trim value could lead to such an extreme event that would result in an average of 45 degrees nose down pitch and 320kts. With 4 units of trim, flaps up and 320kts and no pressure on the control column, the aircraft would surely not be in such an extreme attitude.
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