The new Chinese carrier fighter, the J-15, is supposed to have a more powerful Chinese made engine so that it can carry more weight using the ski jump deck on the new Chinese carrier. The ski jump is a cheaper and less complex alternative to the steam catapult. One disadvantage of the ski jump deck is that it cannot launch aircraft as heavy as a catapult can. China has developed a more powerful version of their WS-10 engine (the WS-10H) for the J-15 but has only been seen in two J-15s. Most J-15s are still using Russian AL-31Fs. China keeps details of its WS-10 development secret, but they cannot hide which of their aircraft are using the WS-10 and which the Russian made AL-31s that the WS-10 is based on and is supposed to replace.
The first WS-10s began showing up in J-11s back in 2004. In 2010 China revealed that it was replacing the Russian engines in its J-10 fighter, installing Chinese made WS-10A in place of the Russian made AL-31FN. Shortly after that announcement China ordered another 123 AL-31FNs, to be delivered by 2012. More AL-31s have been ordered but at the same time more Chinese fighters are being seen with WS-10s.
The Chinese claim the WS-10A is superior to the AL-31F, even though the WS-10A copied a lot of the Russian technology. The Chinese say they have improved on that. For example, as delivered from Russia, the original AL-31 was good for 900 hours of operation. The Chinese claim their engineers figured out how to tweak the design of the engine so that it would last for 1,500 hours. Russia has since improved their basic AL-31 lifetime to 1,500 hours, and, most recently, 2,000 hours. When pressed, the Chinese claim that they simply cannot produce enough WS-10As for all the new airframes they are building. But the reality is that the WS-10As have some serious, unpredictable and persistent reliability problems.
Back in 2011 China believed it would be free from dependence on Russia for military jet engines by 2016, which implies that Chinese engine manufacturers still have a way to go. Now the most any Chinese will admit to is that there will be no need for Russian engines by the end of the decade. Meanwhile China continues to import AL-31s and the RD-93 (a version of the MiG-29's RD-33) for the JF-17 (a F-16 type aircraft developed in cooperation with Pakistan) from Russia. These engines are expensive, with the RD-33 going for about $3 million each and the AL-31 for about a third more. In the meantime Chinese engineers have managed to master the manufacturing techniques needed to make a Chinese copy of the Russian AL-31 engine. This is part of a program that has also developed the WS-13, to replace the RD-93 as well. While the Chinese have been able to build engines that are durable, they are still having problems with reliability. Apparently it is still worth buying more Russian engines because the Chinese models are out of action too often, which keeps the jets grounded for repairs or, worst of all, an engine change.
China has long copied foreign technology, not always successfully. But since the 1990s China has poured much money into developing a jet engine manufacturing capability. The Chinese encountered many of the same problems the Russians did in the beginning. Developing the necessary engine design and construction skills is difficult. But China has several advantages. First, they knew of the mistakes the Russians had made, and so were able to avoid many of them. Then there was the fact that China had better access to Western manufacturing technology (both legally and illegally). Finally, China was, unlike the Soviets, able to develop their engine manufacturing capabilities in a market economy. This was much more efficient than the command economy that the Soviets were saddled with for seven decades. The Chinese consider the J-10 and WS-10A part of the learning process, and they do learn from their mistakes.
Meanwhile the Chinese can build more Su-27 clones than they can reliable engines for them, and they keep developing more Su-27 variants. The Chinese J-11 jet fighter is an illegal Chinese copy of the Russian Su-27. It all began legally in 1995, when China paid $2.5 billion for the right to build 200 Su-27s. Russia would supply engines and electronics, with China building the other components according to Russian plans and specifications. But after 95 of the Chinese built aircraft were built Russia cancelled the agreement. Russia claimed that China was using the knowledge acquired with this Su-27 program to build their own copy of the Su-27, the J-11. The Chinese claimed that the J-11 was designed and built using only Chinese technology. China also has a stealthy version (J-17) of the Su-27. There is also an aircraft carrier version of the Su-30 (the Su-33, obtained from Ukraine) that is now in service as the J-15. In 2013 J-16s were spotted. This is a two-seat fighter-bomber similar to the American F-15E and nearly identical to the Russian Su-30MKK. China insists these are all Chinese designs that just happen to bear some resemblance to Russian fighters.