How do I know? As if I make up all this? The chief designer of C919 says it. China is leader of 3D printing. You are naive to think all 3D printing is same. Material use, size and quality? They are all different and China is world leader in 3D printing. The bigger u 3D print it. The more technical challenges it is. 3D print eliminates bold joint and traditional welding. Therefore reduces weight and strengthen groundwork. It is critical especially in aviation building where weight reduction is important.How do you know that?
Also, 3D printing is now applied in all advanced processes according to need. Also, 3D print by itself doesn't mean efficiency.
Again, I am saying nothing, just reserving my judgement for the future. The actual results can only be known by independent third party testing and operation.
Western stupid source jealous of rising China will badmouth and claim C919 is outdated and full of BS. This is the upbringing and their civil moral. Lying and smearing when they cant beat you fair and square in competition.
https://www.forbes.com/sites/ralphj...asian-world-lead-in-3d-printing/#6f463b77f54e
https://3dprint.com/175556/china-jet-3d-printed-metal-parts/