Originally Posted by
CONF iture
As the elevators did not follow the pilot request, there must be a reason. That's the job of the BEA to detail that reason.
No, it's the job of the BEA to ascertain the factors relevant to the accident sequence, and the report they produce will focus primarily on those. In this case, a discrepancy in surface deflection versus command at a point in the sequence when the flight control system is already compromised - and as such would have no bearing on the outcome - is likely to be a waste of effort. Therefore they note the discrepancy and leave it at that.
Look at the UPS 747F report. The investigators can say that whatever the fire and heat were doing to the control junctions was affecting the control surface response in terms of control input versus surface deflection, but they don't have sufficient data to say precisely what the damage was. Because in that case it was directly relevant to the loss-of-control sequence they consider scenarios, but all those scenarios are speculation.