Originally Posted by
fotoguzzi
[Not a pilot] FO asked for permission to try "manual," received permission, and gave up, all within an eight second period.
That would not seem related to the gradual change during the (from memory) two and one half minute period.
That exchange was at/after the electrical trim was re-enabled, I believe the 'manual' refers to electrical trim switches.
The slow change (wrong direction) was while electrical trim was disabled.
The prelim report did not include much (if any) CVR details from that time, does not mean things were not attempted.
LooseRivets:
That double blip of the thumb switches. The big question seems to be, why didn't he continue trimming? I know of no circuitry which will do this, but what happens to that Stab input if it is already exceeding some load limit? i.e., could there be an electrical current limit that clips the power to the Stab motor/clutches if the motor is taking current commensurate with torque that's too high?
Without knowing exactly where the fdr gets its inputs hard to be sure, but since the automatic and pilot trim inputs are shown separately I suspect the 'blips' are commands not motor activity.
One thing that does comes to mind is a different pilot doing the trim, this matches the same ineffective inputs seen in Lion Air aftert the pilot transfers control to FO.
Is it possible that the last pilots in each case were not used to and or afraid of the long inputs that would have been required?
The only "non pilot" thing I can think of is something that made the switches harder to press/confusing/fail while applying extreme pull.