CutiePie -
I have NO expertise in this. But I do have a friend who was a flight attendant. I told her of my turbulance fears as well and she said, "Just look at the flight attendants' faces. They are used to major turbulance. If you see them looking a little worried, making glances at one another, or stopping what they are doing to start doing something you don't normally see, that's when you should worry."
I've seen this in action. I had one of those flights where the bumps made pretty big drops, and all the passengers sort of looked at each other and grabbed armrests, but the flight attendants kept right on working as if nothing had happened.
Of course, this doesn't answer your question as far as the plane's structural integrity or anything, but it might help your fears a little!
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