China's first large domestic commercial jetliner, the C919, is undergoing final assembly in Shanghai in preparation for its test flight, according to its manufacturer Commercial Aircraft Corp of China (COMAC).

COMAC explains that the general assembly includes two stages; one is fuselage assembly, which has been completed.

The other is the installation of the flight systems, known as the "nerves" and "brain" of large aircraft. This is more difficult than the first phase, and is progressing smoothly.

COMAC received orders on the first day of the just-concluded 51st Paris Air Show. PuRen Germany Gmbh, owned by China PR Group Co, signed a contract for seven of COMAC's shorter-range regional ARJ21-700 and seven C919. Ping An International Financial Leasing Co signed for 50 of C919 at the show as well. This brought to 507 the total number of pledges for China’s first large passenger jet under development.

According to previous media reports, the first delivery of the C919, a narrow-body plane with 156 to 168 seats considered a future competitor of the Airbus 320 and Boeing 737, will be pushed back to 2020.

Industry experts said that potential delays in delivery of new aircraft are not unusual in the aviation industry, adding that China must be certain of the safety of the jets given the lack of experience in developing commercial jets.