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Old 1st Apr 2019, 10:36
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GordonR_Cape
 
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Originally Posted by infrequentflyer789
Peter Lemme has previously suggested that MAX no longer has separate SMYD "box" - however he retracted that a couple of days ago in https://www.satcom.guru/2019/03/aoa-...oeing-fix.html
The human factors comments in that article are just as interesting as the AOA analysis. Apologies if already quoted:
The response to a stabilizer runaway is to cutout the electric trim. Nowhere does anyone caution the consequences of using manual (turn the wheel manually) trim. The manual trim wheel can be very hard to turn if subject to high aero loads, and particularly if the elevator is commanded significantly (loading the stabilizer).
The standard response to just hit the stabilizer cutout switches and manually trim is actually flawed. If the nose has been pushed down by significant mistrim (nose down stabilizer, nose up elevator), and as airspeed increases, it may not be possible to trim the stabilizer manually nose up without letting the elevator go to a neutral position. The reality, under the MCAS runaway scenario, trimming nose up immediately stops MCAS as well as trims the stabilizer back towards an in-trim position. At that point, you would be best off to cutout the stabilizer.
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