PPRuNe Forums - View Single Post - MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
Old 8th Jul 2019, 16:04
  #1231 (permalink)  
safetypee
 
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#1236,
The speculation about the time that MCAS could run in normal operation is misleading, without foundation.
Previous technical discussions identified a maximum time proportional to the required stick force required from tail trim to meet stability requirements. Most flight conditions would require less run-time to meet the need, where need is defined by an elevated AoA and required stick force; not stall - perpetuating the myth.
https://www.boeing.com/commercial/73...e-updates.page

Associating stall awareness, stick-shake, with an inability to determine that the trim operation of a previously undisclosed sub-system had malfunctioned is both illogical and misleading.
Stick-shake had been operating continuously since take off; erroneous MCAS trim only after the flaps were up - suggesting that the crew had a revised appreciation of speed, even if not all of the other distracting alerts.
Supposition that the abnormal trim operation should have been identified, not requiring xx time because yy; has no substantiating argument, or apparent awareness of the limitations of human performance.

Generic procedures for an approach to, and at stall, do not relate to ‘unloading’ the aircraft; a term synonymous with normal acceleration. The primary objective is to reduce AoA, nose down pitch control, which in many circumstances will reduce normal acceleration.
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Re AoA Disagree
https://boeing.mediaroom.com/news-re...ts?item=130431

Re #1239, the implication is that the AoA Disagree system as configured, did not flag a comparison fault in the maintenance system.
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