OK – I don’t understand the Logic of a rubber washer, I have the O-Rings installed under my Propellers and I now have had a 3rd Prop fly-off. Once more the prop flue off when I was landing, just inches from the Ground. No damage to the Bird the Prop or me! I use my Drone to fly roofs from my Home Inspection business, bought the Q-5004k for two reasons; Photos or Video at the push of a button in flight and this aircraft is so quite, my Phantom II sounds like an oversized weed wackier people come out of the wood work to see what the noise is all about when I’m flying! I bought my Q-500 last November and have only used her for one Inspection; she went up about two feet and flipped! I places my Phantom II up for sale the night before the crash and but I pulled the ad the next day! I’m still flying my Phantom II almost daily (sometimes twice a day). I am to the point where I’m afraid to take the chance on my Q-500 4k crashing into a neighboring home or injuring someone, I’m going to go out in the Desert and fly my Q-500 in a large open space,but until I fully understand why I’ve had 3 Props fly-off, the Q-500 will not be used in Public. I’m wondering if maybe it’s the O-Rings or if it’s a bad Motor shaft – I’m confused on this whole thing! General Question: to fellow Q-500 users: Who is using the O-Rings under the Props and who isn’t? Is Props flying off common or a Fluke?