A VS separation would result in a high forward speed impact with the sea rather than a low forward speed, high vertical velocity impact. The evidence just isn't there for any high forward speed impact. Fragmentation of interior cabin parts was not high in this accident. Large, relatively fragile structures survived, intact.
Neither do I think that there is much to learn that we don't know already from the Japan Air B747 which lost the VS through loss of the aft pressure bulkhead and AA 587, in terms of pilot handling
PJ2 (page 20)
Dear PJ,
In relation to your first comment, that a loss of the VS would necesarily result in a high forward speed impact, I doubt that this is sustainable as an outcome. On loss of the VS/Rudder assembly, the aircraft will be at best left with marginal lateral stability, and at worst will be divergent in yaw, which we have seen in the failure of AA587.
In relation to the second comment re pilot handling, do you not consider that a design certification criteria and subsequent design that can be overloaded by sequential torsion-bending loads within the limits of the rudder force (ratio) limiting system is not a factor rather than merely pilot handling? Note as well, that the functional design approach taken by AI on the rudder limiting effectively increases the sensitivity of the rudder in respect to the operators input. ( the system limits throw of control, and thereby rudder deflection, not reducing rudder deflection but maintaining the control throw). Further, the AA587 loss highlighted the massive misunderstanding of operators generally as to the application of Va.
In the event of a compound ADC failure, all bets are off as to control gain and FBW stability systems, and the potential in moderate severe turbulent conditions to result in a control system initiated structural failure remains possible. This is not limited to pilot only control inputs, as the FBW system would until reverting to direct law be acting in 2 channels to retain attitude. Whether this did in fact occur to 447 remains an open question, but is probably inconsistent with the BEA's observation of a failure of the VS/rudder on water impact. I personally find that opinion, and the available data inconsistent, suspect that the loss of data airborne and the preceding system degradations indicative of structural failure airborne, with VS separation a potential consequential failure following the ADC and turbulence encounter.
Rather than having a high speed impact following an inflight VS separation, I would be expecting a relatively low speed impact, potentially with moderate vertical rate. Note that even with JAL103, which retained some lateral stability, the KCAS varied enormously as a consequence of the phugoid, from near stall to high speed. On AA587, the VS failure resulted in divergence in yaw (with beta dot much higher than encountered during the control input phase pre VS separation), and rapidly the separation of both engines under excessive lateral load of the pylon attachments. The aircraft at this point had no thrust, hydraulics, and was pretty much limited to uncontrolled directionally unstable descent as a falling object with path modified by the remaining aerodynamic appendages operating at varied relative airflows.
Just a thought...
FDR