I've not seen others about this, but if I missed it please forgive. But I had four landings where all motors revved, the H kicked backwards and cartwheeled. The first time broke two props. It was after that 4th time I put it together what was going on... that I was taking off with the OBS toggle in ON position. Sure enough, I made sure it was off and all was fine. Odd thing...it didn't happen every time. So I called Yuneec and they verified to absolutely not takeoff or land with obs Avoid on I was told they are updating the manual to include this. I share this only as a warning to all to beware.