I dug into this a little bit more. Mechanical things of all types fascinate me.
The missing fan blade is at the 8~8:30 position, and there is some damage distortion to a few others.
This damage is strikingly similar to another incident in 2016 to the same engine type where the front cowling is completely torn off.
Testing procedures include blowing off one fan blade. This is to validate the design requirements that the blade is to be contained within the nacelle, and also to validate the engine fan’s ability (along with the entire engine assembly) to withstand the resultant out-of-balance condition.
Conjecture on a video I saw proposed the resultant vibration tore off the front cowling. While test videos I’ve seen demonstrate no cowling tear-off, I don’t know if the simulated testing damage also was done in a wind tunnel.
Heavy vibration + air speed forces may have coupled together to do this.
interesting statistics on airplane accidents
http://www.boeing.com/resources/boeingdotcom/company/about_bca/pdf/statsum.pdf
interesting statistics on airplane accidents
http://www.boeing.com/resources/boeingdotcom/company/about_bca/pdf/statsum.pdf
So, blade fails. Damaged and weakened cowling is “peeled back” like peeling a mandarin.
Now it makes more sense.
And, the fuselage damage not having remains inside reminds me of a movie scene (MI, Matrix?) where CGI was used. Projectile penetrated pressurized plane window and -in slow motion CGI- the plastic window broke into pieces, hesitated in mid air as the projectile went through and was then shown being sucked out the opening.
All neat and tidy, inside.
As I mentioned previously, the altitude conditions probably enhance shattering. I assume the testing parameters concentrate on flight zones with the heaviest stresses/probability of failure, which are nearer seas level and warmer.