I check that it fits the uprights, which it does. Note how it adds to the integrity of the overall structure, all be it not totally immune to a degree of twist. This is nothing to be frightened of, however: I used to marvel while waiting to taxi how MD-80 airliners would bow like a sausage-dog over every bump. Likewise the fuselage of the 757 was renowned for twisting remarkably along the length of its cabin.
