A few not unreasonable concerns expressed on the possible risks of some sort of structural failure during tests. The TU 154 is a pretty sturdy beast but, I wonder what the condition now is with regard to basic structural integrity corrosion wise. If that airframe has been around in Iran for any length of time, one might start to worry on that side of things also. This might well be an additional factor; the straw that broke the camel's back even