defeating the RTF ,,, always build your own ,.,. lol .. cheaper ,, but man glad no one got hurt
The blade and the wearable bearing inside the feathering shaft assembly are the most common problem on this heli, HK or any brand. Mine is an authentic Align 450 and the first time I got it, the blade holder/feathering shaft assembly was very tight and I thought they were ready to go. So I did not remove it and locktite it. The screws that hold the wearable bearing came apart during a flight, just like what happened to yours. You can guess the result.
Another time, as a newbie trying to save some money and bought some cheapy Glass Fiber blades. Spool up and testing things inside my bedroom and the blade itself came part from just spooling up. Here is the result:
A blade flew one way and the heli flew the other way. I was about a foot away from the TV corner so the blade pretty much missed me by a foot. It looked like an explosion when it happened.
The tip of the blade is still at the blade holder: