PPRuNe Forums - View Single Post - MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
Old 8th Jul 2019, 17:03
  #1235 (permalink)  
bill fly
 
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Originally Posted by safetypee
#1241, Is an unusual description of trim - stick force and aircraft control.
Most professional pilots already have an adequate understanding of this and the various relationships, including speed - thrust, and configuration.

The primary objective of control is to achieve the required flightpath (not where the trim is going), using stick input to change pitch. When a stable condition is achieved, including speed, then trim can be applied to reduce stick force.

Differences in views about the ability to identify a trim runaway, perceive, comprehend, relate, and choose action (checklist) appear to be fundamental to the current delay in return to service.

See issues of trim awareness Loss of Control In-Flight - Flight Crew training U.K. CAA safety Notice http://publicapps.caa.co.uk/docs/33/...ice2019005.pdf
Quite right. That is normal piloting.
However if the trim should for any reason be so far out, that the elevator has too little authority to correct the pitch, it may be necessary to trim simultaneously with pulling back.
And right there, in an extreme case there can be a problem with overloading of the trim mechanism in the tail (irreversible worm drive/screw jack), which is the reason for the unloading or sea saw procedures previously promulgated in jet-upset recovery advice. And as we know unloading at treetop height - even if you know how to do it - puts you in the ground.
B

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