Originally Posted by
Grebe
From the view of this interested SLF re yoke-column cutout switch. Believe you may be missing a point. AFIK ALL NG versions for the last several decades had operable yoke cutout swiches such that if pilot pulled yoke in muscle memory reaction to a sudden or noticeable AND ( dive), pulling the yoke would stop- disconnect the stabilizer, and unless another improbable fault happened, the stabilizer would stop moving and the elevator trim switches would still work. Sort of like if your car due to a flat tire swerves to right or left, your immediate reaction ( unless on smart phone ) would be to twist wheel in opposition.
The pilots in both Lion and Ethopia were never told that the addition of MCAS ( aka HAL ) essentially bypassed that switch. And if they did NOT regain near neutral ( level ) trim before using console cutout switches which cut all power to switches and autopilot and ??, the manual trim wheel was essentially unuseable. And as I recall, one of the recordings showed that a few seconds before flight termination, both pilots were pulling back maximum forc on the yoke which IF in the NG would have stopped the stabilizer AND still left the electric trim switches operable.
Just my armchair opinion
Grebe, respectfully, but is that correct? From my FCOM
Control column actuated stabilizer trim cutout switches stop operation of the main
electric and autopilot trim when the control column movement opposes trim
direction. When the STAB TRIM override switch is positioned to OVERRIDE,
electric trim can be used regardless of control column position
It would appear to me that moving the CC in a direction opposite the trim(actuating the control column cut out switches) would stop ALL electric trim! Also the control column trim switches!
Often arriving in an airplane with electrice HYD pumps off with the control column slightly aft, trying to reset the trim to approx 5 units during preflight(as my college’s didn’t do so during taxi in), this is not possible with the control column trim switches until I push the control column slightly forward.
that is also the reason we have the STAB TRIM override switch I thought.
greetings.