Nobody said that the CJ-1000 has made its first flight on the C919's maiden flight...According to the sources, I don't think CJ-1000 has been tested on the flight. What this news said is the new aero-based engine test platform made its maiden flight and the engine mounting test. It's a new platform, so it's essential to test if all the systems and functions are good in the sky. So, why mount a brand-new engine on its maiden flight? After the test platform is confirmed to be perfect, then it will enter service and its first customer will be CJ-1000. What we will see then is "the new aero-based engine test platform finished its first test mission."