Thank you for the excellent post
A33Zab
The PF slight but consistent nose up command is a +G request to the PRIMs, the A/C feedback by means of accelerometers however results in a -G.
PRIM deflects elevator and due to negative result drives the THS all the way ANU.
Is there a threshold of displacement for the sidestick before inputs are valid? How slight is slight? In the a/c I drive, stick neutral and elevator neutral are not the same thing. This lends the stick a "loose" feel in its neutral position. As
CONF iture mentioned:
A particularity of the sidestick, depending how you grab it, is that it can be easy to involuntary command a NU or ND input by implying a generous side input.
Was that NU input intentional ...
PS: Can we infer the NU displacement from the info in the report:
The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight.
10 degrees in 1 minute. Are we talking about a displacement so small that, let alone the PNF, even the PF might not have noticed the input?