Flick rolls
Think of the enormous disk area and weight of 5 blades on the later model Spits. Changing this spinning disk's plain of rotation suddenly causes an extremely high gyroscopic bending force on the prop shaft, to the point where, if a previous stress failure crack is present, the prop shaft will break off the engine. This will be the case in all props when, over time and numbers of violent maneuvers, a failure will result.