Well, gentlemen, DozyWanabe posted
excellent link dealing with both AA587 crash and post-mortem investigation. For those of you who didn't bother to follow it, here are some interesting excerpts:
The point seems to have been that because one could not
well calculate such overloads, the industry (regulators and
airplane builders) relied on instilling as Best Piloting Practice
that you Just Don't Do That, because you could rip the tail
off an airplane.
Now, that seems to me both reasonable and consistent with
professional operator practice anywhere. If you Don't Know
(and you know that it can be catastrophic) then you Don't Do.
(...)
It is recognised in the industry, although not apparently
at American until recently, that swinging the tail around with
rudder is something you Just Don't Do. Most pilots of large aircraft
(I would have said: pilots of large aircraft, until I learnt
about American's training) are taught to use rudder only at slow
speed (take off, for example) or to correct yaw in an asymmetric
thrust situation.
(...)
during thirty years of A300 flying, American has been the only airline to rip off (or, in another incident, almost rip off) the tail, and that through
explicit use of rudder
(...)
Nobody I knew, including some avid Airbus Design-Flaw Seekers,
ever doubted that the dynamics of the aircraft as shown on the
FDR were highly inappropriate. The debate centered on whether
one could conclude that the pilot did it (rudder pedal travel
was not recorded on the FDR) or whether some automatic system
had gone awry. Obviously, the NTSB's attempts to find some
rudder control system that had a failure mode that caused such
motion came up with nothing. (I am inclined to think that if
the NTSB cannot find one, then nobody can. They have a lot of
experience and succeeded in finding the failure in the
Parker-Hannefin yaw damper in the B737 after the US B737
crash in 1994, and the failure mode of the thrust-reverser
interlock on the B767 engines after the Lauda Air crash in
Thailand.) So even the design-bashers agree that if indeed
the pilot did it, he shouldn't have done so. The NTSB is finding
that indeed the pilot did it. All else follows from that.
So which part of it you don't understand?
When I was I young lad, one of my instructors told my group that you never, ever rapidly cycle any flight conrol (while airborne, that is), for any reason, on any aeroplane. You could easily get in resonance with airframe, develop severe oscillation and enjoy the view of airframe disintegrating around you. And only after listening to this and a lot more of solid advices we were allowed to sit in our mighty cessna-152s for the first time. Lucky me that the chap who told us that was ex-glider pilot, ex-cropduster, ex-dakota pilot (both Douglas and Lisunov) and ex-DC-10 instructor and not someone who passed aerodynamics and airframe construction test by learning all multiple choices questions by rote and than spent a year or two instructing just to build up hours.
Lucky me indeed, because nowadays, when I open my FCOM, foreword tells me:
the text is not intended to teach the crew how to fly an airplane, but to enable an experienced crew to operate the related airplane type safely and proficiently.
Learn, live long and prosper!