AF 447 Search to resume

[bearfoil]

Machaca

Dating from BA038, you do come up with the best and most helpful diagrams.
Wish you'd talk more, but.....

The failed Lug you bring up is what would be 3A if the Lugs were indexed Fore/Aft and Port/Starboard. As I see it in any case. Basically, at the point of peak energy, acting to pull the Lug free (up) out of 3A bracket, The Rudder has just reversed from a Starboard correction (reversal) and the Fuselage has swung right (Tail Left). The Rudder then is commanded full Left, the VS is exposed to peak shear, peak Tension, Maximum Torsion, and just as the Fuselage is at it's most right YAW, the VS is loaded beyond Limit (Ultimate). All three forces reach Limit concurrently, and the Lug Shears/Bracket Releases. The Noise must have been LOUD. The way to simplify the image is to imagine the tip of the VS straining over to the Right, the axis twisting counterclockwise, and Tension is a Triangle, the strongest structure in Engineering. The Triangle consists of the forward and (partially) middle lugs, the tip of the VS and the Left Rear Lug, the Peak of the triangle. There is a fulcrum at 3B.
The failing Lug pulls out, and the VS is essentially at failure. Even at this point, if the Rudder had been centered (by any means, including leaving the a/c), the 300 may have been saved. The first failure was not the Fatal one,imo. The VS still was attached, and more reversals finished the separation as evidenced by the sequence of Thumps on the CVR.

I think if we keep in mind the energy it took to uproot this Vertical Stabilizer, we get to the place of contemplating a solution for the next iterative wide-body, the 330.
Limit load for gust is half that of demonstrated catastrophic failure. At the point that the problem began, Wake Turbulence was behind and the jet should have been climbing out. Is twice the limit load a necessity? No, not at all. The limits are sound, and workable under all conditions. Why did the aircraft crash? WT? No, not in any direct way. It is a cause only in that it started something that should never have happened. Over Control, maximum Ruddering, at maximum rate. Why? The pilot was alternately stomping on each pedal? Out of phase 180 degrees? I do not think so. The pilot and the machine had no idea what the other was doing? Possibly. If the conclusion of the NTSB is that the pilot cycled the Rudder like a novice, also, no.
The Airplane can fly without a Rudder, It cannot stay airborne without a Vertical stabilizer. A small Pitts or Extra can flop its surfaces helter skelter, a 180 ton beast can not. (Not as currently manufactured iac)

Bear