Originally Posted by
G0ULI
The two previous whirl mode crashes involved structural failure of the wing at the wing root and subsequent loss of a complete wing while the aircraft were still in the air. That was clearly not what happened here as both wings remained attached even after striking the railroad embankment. Whirl mode can therefore be dismissed as a factor in this accident.
Hi Gouli,
Whirl mode is what leads to wing loss, but only if there is a wing flutter component attached. There needs to be a (wing) sympathetic flutter concurrent and matching at low Hertz. These “partners” exacerbate the stress beyond just mount Slop, and beyond structural limits.
What I saw in 1969, (post LEAP), was a widening divergence from center thrustline, which got to what I estimated was a fifteen degree deflection, each way, for a total of thirty degrees “back and forth”. We were landing and in still air; I still noticed the wing twisting in three separate directions about its spar. As soon as the thrust went to idle, the show stopped.
I am trying to point out that not losing a wing does not eliminate Whirl Mode as a possibility as cause of aileron damage.
Would you care to comment? On the flap/aileron experiment?