Data shows that the mechanical response of Francis runner blades is sensitive to power plant control systems. To demonstrate this, we have explored two such systems: wicket gates opening and air admission. The proper control of these systems does more than warrant safe operation; they can also be used to minimize the strain cycle amplitudes during transients such as: startups, shutdowns and load rejections. Proper control parameters settings should minimize the equipment risk of fatigue failure without negative side effects on other components and objectives. With the help of measured examples from Hydro-Quebec power plants, this paper demonstrates that a better understanding of these systems is needed in order to move beyond costly trial and error fine-tuning methodology.