Dennis Muilenburg, chairman and CEO of Boeing. The company says 1 out of every 4 jetliners rolling off its assembly lines is being bought up by Chinese customers.

A major step towards the launch of a Boeing 797 has been taken after different engine makers were reportedly given until the end of Wednesday to detail how they would power the airplane.

In July 2016, Boeing forecasted a 4,000 to 5,000 aircraft demand for a new “middle of the market” airliner. The plane-maker suggested it could achieve a service entry date of around 2025.

Now, the first version is reported to be the NMA-6X, a 228-passenger medium-range aircraft with a 5,000 nautical mile range. A second version, the NMA-7X would be larger with 267 seats, but a range of 4,200 nautical miles.

Both concepts would evolve to become the Boeing 797.

According to the aviation magazine “The Air Current,” Boeing has given the manufacturers a Request for Proposals (RFP) deadline of June 27 to submit plans for a new engine that burns 25 percent less fuel than turbines used on Boeing’s 757 planes.