Bendy Airbusses...
Excuse me if this turns out to be a stupid question, but it's been bugging me for a while.
I became aware a while ago that Airbus A330/340’s have a built in “sight tubes” for levelling and alignment of the airframe. Presumably, by the very fact that these devices are present, the airframe can become “misaligned”. Under what circumstances can this occur? A landing at MLW in excess of 660fpm, severe turbulence? Does this happen naturally over the lifetime of the airframe, i.e., does the aircraft “sag” over time?
A final question: If misalignment is detected, how on Earth is it corrected? Are there “tensioners” built-in at specific stations along the airframe to “pull in” the stringers, or are adjustments made elsewhere on the airframe, for example, aerodynamic modifications?