I fly with a 3W 170 and tried the THREE Bladed Mejzlik 28x12 at 5800 ---28.5x12 at 5550 ---and 29x12 at 5350----All 3 broke in flight----Mejzlik refunded money. Want to try the THREE blade Biela 29x12 but am really scared if it will safely handle a 5350 to 5500 rpm.Anybody use these at these rpm's for long?Yesterday I was flying with a Fuchs TWO Blade 32x12 at 5100 rpm and it broke in flight after 5 flights---The 2 bladed Mejzlik 32x10 at 5750 rpm is the only prop which has run 250 flights and no breaking but is noisy.