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Old 4th Nov 2018, 21:28
  #589 (permalink)  
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Join Date: Jun 2009
Location: florida
Age: 77
Posts: 1,193
Salute!

Dat's right, Henra.
++++++++++++++++++++

Had to go back to the Alaska Airline crash with the " jackscrew nut. Wanted to see if there had been a squak on a preceding flight. Couldn't tell, but it would seem to me with all the damage that jackscrew had and the metal trapped in the big nut, that there would have been some slight indication to the PF. OTOH, with the use of the AP, the jammed stab was overcome by basic elevator trim. Finally, aero forces and commands by the PF caused the frst failure.
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Looking for a silver lining, this crash is a wakeup call to examine not only procedures but the design of the stab and pitch feel system, then all the air data inputs.

I tend to go with 'bird ( as in Machin') about possible PIO due to bad data coupled with a flaky pitch trim. You do not need a massive structural failure to reach extreme vertical pitch and speeds. We saw that at Rostov and that whole maneuver was done by the crew ( still have chills seeing the video). And one of our 73X drivers here claims that losing some or all of that trim/feel system can be challenging, especially at higher speeds.

And I have been a non volunteer test pilot on at least two flights, two types. Not fun. Only one required instant action and even that one I did the "don't just do something, sit there!" for first few seconds. Jet was still flying, so whatever I had was good enuf for then. picture on my PPRuNe profile bio.

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