I hv two cc3d, one is fitted on my F550 and another on 250 size tricopter.
But last week it behaved so strange!
I'm a ruff flyer(i.e. I fly fast and do acrobat with them.)
I did a 3 min flight and at 150ft height i started hovering.
But suddenly it came to ground with a free fall
Nothing damaged except a motor mount and one prop.(my lady luck)

Has any one experienced it before?
What can be the reason?

I have experienced something similar with my quad running a naze32 acro. I still cannot figure out what happened.

seems like a ESC glitch..

if the quad is working fine....you can use a  harness to tie the quad on some weight so tht the quad dosent fly...and try to keep the throttle at 50% and check for any faults...

I tried using other fc now and its totally fine.

this will happen when one or more esc lose sync.

solution

use escs that have sufficient max load margin.
do not over prop
do not set the refresh rates of esc too high

here are spec. of my Quad-
Bumblee motor 930kv
DYS 30A simonk ESC
Fly sky 9ch Tx-rx
3s 2200mah lipo 40c