okay this is very interesting stuff.View attachment 162189
The material schematic diagram of MS-21 released by the Russian side. Pay attention to SYT-55 in the picture.
View attachment 162190
SYT-55 was developed and manufactured by Zhongfu Shenying.
I do know that Russians import some CF from China, but didn't know they did it for MS-21. Far and away largest CF importer from China is actually Vietnam.
Also C919 project uses SYT59G-12K, which is an improved version of T800, whereas SYT55 is the original T800 product. So looks like C919 uses more advanced CF than MS21,