Another question is about how much turbulance an aircraft can deal with. It was explained to me once (by a Flight Engineer on 747's) that if a 747 was dropped from 50 feet it would not sustain any damage and that gave me huge peace of mind , particularly when the aircraft has had a heavy landing.
The B747 has a maximum rate of descent for landing at max landing weight of 600 feet per minute, and at max takeoff weight of 300 feet per minute. A drop from 50' is equivalent to a 3000 foot per minute touchdown; definitely adequate to damage the airplane. I believe the FE was selling you something that perhaps he ought not.
The amount of turbulence an aircraft can handle really depends on the aircraft, how it's loaded, and it's speed at the time. The nature of the vertical gusts and their intensity directly impact the load on the airframe. Aircraft can, and do break up in turbulence and can and do experience losses of control in turbulence. The degree of turbulence required to cause an upset or structural damage, however, is substantial, and very uncommon.
When entering turbulent conditions we have maximum speeds to fly, which are directly related to protecting the airframe from excessive loads. We also minimize abrupt control inputs, particularly in turbulent conditions.