The official account is that the first installation of WS-10A on a plane was Sept 1998. I'll take your word for the first test on Su-27SK because then they need Russian assistance to adjust the body part. WS-10 is bigger than Al-31FN.WS-10A wasn't even in existance for early J-10 prototypes. The first time it was tested on an aerocraft was an Su-27SK in 2002 where it failed miserably.
It's not neccessary to be rude. You are the boss to decide the sale. I read some of your comments on WS-10A. You are right that Chinese have problems with the quality but they are under batch production. They work quite OK on J-11B.It is fine, we just ordered 96 from Ufa. Su-27SM2 upgrades will be coming online next year. This engine will not be offered to China due to fears of intellectual property theft.