Originally Posted by
waito
Allright, here Special FDR's from start of T/O roll (FDR tabular data starts at 20:40:00 anyway)
(Edit: replaced Plots with better ones)
Overview:
Following Plot with Heading in higher range, Rwy Hdg marked with yellow line, Rudder Zero marked with blue line
I reversed HDG here so +y is left turn to match rudder orientation:
Thank you!
So there was indeed at the beginning on average a relevant left deflection of the rudder while heading was more or less stable and straight. The average Rudder deflection almost linearly decreases from slightly below 10° to around 5° at takeoff speed before suddenly and continuously being deflected to 20°.
Reducing of deflection would match the correction of a cross wind (or the nose wheel not pointing exactly aligned with the rudder, but this would have surely been identified since).