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Old 3rd May 2019, 11:55
  #4789 (permalink)  
Lost in Saigon
 
Join Date: Jul 2004
Location: Found in Toronto
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Originally Posted by CurtainTwitcher
In the isolation of a simulator session where the sim instructor selects a runaway trim malfunction, fully agree with you.

Press play below before reading on...

https://youtu.be/TrjTUvhpBlE

This was not a classic runaway trim. No trim issues were encountered until the flaps were retracted. Retract flaps, now some forward trim starts, trim back with the electric trim and everything is good for 5 seconds, just enough time to start thinking about else, there goes the trim again, fix it with electric trim, all good for 5 seconds, repeat until end of sequence. You are also dealing with an airspeed unreliable. Not easy with that racket going on the background.

To the pilots in all three event flights, this was a trim fight, not a continuous runaway in the QRH condition statement for a Runaway Stabilizer. Judge for yourself from a current in-service document:

Condition: Uncommanded stabilizer trim occurs continuously
The trim worked as they expected, sort of. If English was not your first language, it would be even more difficult.

The Lion Air crews were in the worst position, they had no prior knowledge of the subtle system changes and faults that had led them to trim fight, not a runaway.

Originally Posted by L39 Guy


Runaway Stabilizer: Uncommanded stabilizer trim movement occurs continuously. (Source B737 NNC)



In November 2018, after Lion Air, some (or all) operators, changed the checklist list and removed the word “continuous”.
























Last edited by Lost in Saigon; 3rd May 2019 at 12:40.
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