Not an expert by far, but I would not assume that the flex resistance of the plastics bottles happen to coincide with the proper pressures (or suction?) of the turbine system. In other words, there may not be any relation between the suction force (?) required to flex the bottle, and the typical suction forces in an adequately designed fuel system for the turbine. If so, then the bottle is not telling us anything when it flex about the adequacy of the fittings sizes, clunk, fuel lines, etc in the fuel system...