RE: what caused the turbine jet crash??!!!!!
I do not think there is enough information. For example, was this your fourth flight of the day? Or the fourth flight on the aircraft? Did you do a control surface check before the flight and if so, were the ailerons and flaps working correctly?
I usually do a flight control check, where I put a slight load on the surface with one finger. This not only shows the surfaces moving in theright direction, but will tell you how good the gear train is.
For example, if you had a bouncy landing the flight before, you could have induced a heavy load on the gear train. One tooth could be compromised. A slight load could detect the bad tooth.