So the "Blades" of a propeller are more related to a blunt non heat treated whirly-twirly than an actual Blade. Given this; when the propeller blade comes in contact with flying "stuff" it is susceptible to breaking or falling apart. In this case (especially because the engine is in front of the prop) an exhaust spring made its way off the engine and hit one of our three blades...pre-flight paid off. On a positive note we can see Larry getting a new propeller :)