Originally Posted by
onsoutherntip 
I am curious as to where the FDR data for the stabilizer trim is read from - yoke trim switches or the motor drive electronics? Most high power motor drives have feedback that detects if the power demand is exceeded. If this happens, power to the motor is disabled, in order to protect it. Therefore a situation could arise where even though the pilot is activating ANU trim, it results in just a short ANU motor movement, before the motor power limit is exceeded. So if the FDR records from the drive electronics, the trim ANU 'request' by the pilot, will be seen as just a 'blip' although the trim switch is still activated,
This would account for AND trim running the full period as motor power demand is not exceeded (low aerodynamic load), but ANU trim is fighting against high aerodynamic load, which activates the motor protection. Thoughts?
I have been thinking the same thing since the preliminary came out but with less Engineering knowledge than you hadn’t come to such a clear position.
I was just thinking “ I bet they were trimming nose up but the FDR only recorded what the screw jack did” without any systems knowledge to explain how that may be the case.