CFM International and the Commercial Aircraft Corporation of China (Comac) have started on a joint definition phase for the combination of the new LEAP-X engine and the C919 aircraft.
This will continue through this year, and the first full engine is expected to go to test in early 2013, says CFM.
Comac chose CFM in December to provide the engines for its C919 single-aisle aircraft, which is scheduled to enter service in 2016.
CFM has said it is looking to establish a final assembly line for engines in China.
Development of the LEAP-X has been "progressing steadily", it says.
"CFM will continue engine development work, including the second phase of testing for eCore 1, as well as running full-scale endurance tests on the Resin Transfer Molding composite fan," it adds.
This will result in the first full engine, provisionally called the LEAP-X1C, which will be tested in early 2013, says CFM.