Russian airframer Irkut has rolled out its fourth MC-21-300 flight-test aircraft from its Siberian manufacturing facilities.
The aircraft is fitted, like its three predecessors, with Pratt & Whitney PW1400G engines.
Its engine covers indicate that the twinjet bears the registration number 73052.
It was transferred to the airframer's flight-test division from the assembly line on 28 November.
Irkut states that results gathered from flight-testing of the other prototypes have been "taken into account" during the production of the fourth jet.
The manufacturer has yet to indicate when the aircraft will fly.
It is set to produce the first example of an MC-21-300 with the rival Aviadvigatel PD-14 powerplant, which is domestically-built.
Irkut first flew the MC-21 on 28 May 2017, with aircraft 73051, followed by 73053 on 12 May last year. The third, number 73054, started flying on 16 March this year.
Two other MC-21 airframes are being subjected to static testing as part of the development process.