China's domestically developed C919 passenger jet has finished all of its test flights before seeking certificates to operate passenger flights, a sign the plane is getting closer to its commercial debut, industry experts said.

The debut of the homegrown aircraft, which would break the market duopoly of Boeing and Airbus, is expected to push the development of China's civil aircraft manufacturing industry into the fast lane, they said.

"The certification is expected to help accelerate the integrated growth of the aircraft manufacturing industry and the air transportation industry, and to further enhance the international competitiveness of China's civil aviation industry," said Zou Jianjun, a professor at the Civil Aviation Management Institute of China.

The manufacturer of the C919, Commercial Aircraft Corp of China, announced on Monday that the aircraft model completed all of its test flights. Earlier, six C919 prototypes had been undergoing intensive test flights in different weather conditions at the company's testing bases in places like Yanliang, Shaanxi province, and Dongying, Shandong province.

The first C919 narrow-body passenger jet is expected to be delivered to China Eastern Airlines before the end of the year, Commercial Aircraft Corp of China said. The company started manufacturing the first C919 aircraft in late 2019, and the work has made progress.

Lin Zhijie, an aviation industry analyst, said that based on the experience of the ARJ21, the first domestically made regional passenger jet, which obtained certificates in 2014, it takes about a month between the completion of test flights and the certificates being issued by the Civil Aviation Administration of China.

"Now, the C919 has entered the final stage before getting the three certificates required to operate commercial flights. First, it needs to get a certificate that attests to the airworthiness of a particular category of aircraft. There is still some paperwork that needs to be done," said Lin, who is also a columnist for Carnoc, a leading civil aviation website in China.

In addition, the model needs to obtain a production certificate, and it also needs to get the last certificate, or a permit, for commercial operation of passenger flights. Only after all three certificates are obtained can an aircraft model be put into commercial use, he said.

The C919 has 158 to 168 seats and a range of 4,075 to 5,555 kilometers. Its competitors include the single-aisle B737 of Boeing and the A320 of Airbus. So far, 815 intended and confirmed orders have been placed for the C919 from 28 Chinese and international customers.

At a later stage, the C919 also needs to get airworthiness certificates from the European Aviation Safety Agency and the Federal Aviation Administration in the United States to operate in some foreign countries.