Originally Posted by
Loose rivets
As I monitor this thread, I still have an uneasy feeling about the chicken and egg logic of the argument. To quote myself.
How sure are they, that the FP's input was not increasing because of an already developing structural failure?
The feedback may have been so modified, that he was reaching further and further for a familiar response.
This still nags at my thinking on the subject.
Because according to the NTSB's scan of the fracture surface of the recovered section of the tail and attaching lugs, there was no pre-existing evidence of fatigue, and the only stress area was at the main point of failure. The loads engendered by the FO's control inputs were capable of making even an unfatigued tail snap because the 'Ultimate' design load was exceeded.
If the tail was suffering from dangerous levels of disbonding and or fatigue then it would have failed well before the point at which it did.