Usually it's Russia that supplys China with parts. What parts do Russia buy from China?
They want civilian airliner parts to help keep their western purchased airliners flying. Makes sense that China would refuse given such parts are not in China’s gift to give as any such parts purchase from abroad would almost certainly have extensive end user agreements and restrictions, with no unauthorised resale and transfer being a cornerstone feature. China will not blatantly break its own laws and contracts like that to support Russia. Not at this stage in any case.
I suspect there is also an element of PR spin involved as well.
However, I am pretty confident that negotiations are already under way for local Chinese manufacturers to make generic common airliner parts that can then be exported without restrictions to Russia to help keep their planes flying without needing China to break any of its own contacts.
