Application of rudder, instinctual -
what has been said of rudder input in normal flight is very interesting and telling. One should consider the animations the NTSB often publish as part of their public dockets. It would seem that a sudden upset almost always leads to rapid, one would say instinctual, rudder input from the PF. Sometimes this may be justified but from what has been said by pilots here, not often. Perhaps this goes back to training days in small aircraft where more rudder authority is required to escape an upset or establish stable flight in turbulence - the ideas imprinted there could somehow just become part of the airman's natural skills.
This aircraft had already accumulated 18000 hours in 4 years - that's a lot of flying. There are many unknowns about how fatigue accumulates in composite structures. We know in one case that the VS mounting lugs failed laterally, all at once, across many layers of composite material, in AA587. This must have taken the structural engineers somewhat by surprise. These things have not been around long enough to know all their properties under heavy use. One thing is sure, they don't respond well to rapidly changing stress like aluminum does, and they tend to fail collectively and not along easily identifiable cracks. One can point out here the failure of the carbon-carbon reinforced leading edge panels in the Columbia orbiter. The collected engineers gasped in amazement as a piece of foam smashed a 50cm hole in that panel - I don't think anyone expected this collective failure mode where a crack develops and propagates at such speed. One thing that may be important to consider is that these structures come out of fabrication with a lot of frozen-in stress that gets released almost explosively on failure.
-drl