Irkut has commenced final assembly of the third prototype MC-21-300, as it prepares to transfer the second to the manufacturer's flight-test arm.
The Russian airframer is expecting to carry out about 1,000 flights during the certification effort for the Pratt & Whitney PW1400G-powered twinjet.
Irkut says, in an update ahead of the Dubai air show, that it is aiming for Russian type certification in mid-2019 and similar approval from the European Aviation Safety Agency in mid-2020.
The MC-21 has been carrying out operational tests for nearly six months, following its maiden flight on 28 May.
Irkut says 20 flights were conducted for early development analysis at its Irkutsk plant, before the aircraft was flown to the flight-test institute at Moscow's Zhukovsky.
It commenced test flights from Zhukovsky two weeks later, on 2 November. The aircraft is being housed in a new hangar at the Yakovlev flight-test complex which features ground-testing and information-exchange capabilities.
"Systems are being tested and software is being debugged," says Irkut.
The second aircraft is being prepared for handover to the flight-test division and the third will follow in 2018, it adds.
Irkut is also carrying out certification work on test benches, with testing completed at 22 of the 56 benches in operation.
It is modifying its Irkutsk assembly lines with additional stations to cope with serial production, putting capacity of the line at 20 aircraft per year, and will also complete construction of an MC-21 logistics centre at the plant next year.