On our last trip to Europe, my wife and I were sitting in the last row of a Virgin A340-300.
On approach into Heathrow, we kept hearing these awful groans and creaks. I asked the flight attendant sitting next to us what those were (though I already had a pretty good idea).
When he confirmed that it was fuselage flexing, I made a mental note to avoid A340's if possible. I mean, the thing sounded like it was crying!
I've flown all my life (both my parents are in the airlines) and never heard anything quite like it on any other aircraft. I can only imagine what those sounds would do to someone who was afraid of flying.