I love my little Sky Angel F16 RC model but last time I tried to fly it, the fan grenaded and blew itself to pieces.
It appears that one (or more) of the motor-mount screws must have come undone and fallen into the fan hub, probably throwing it out of balance and causing it to rub against the shroud -- which then made all the blades shatter.
So, the moral of this story is -- check those motor mounting bolts before it's too late!
And yes... I did see that the washers came from the motor shaft :-)
Now I just have to find a new fan for this plane -- it's too good to throw away and the weather is great, now that spring has *finally* arrived!