One of the pairs of China's first domestically produced regional jets, the 90-seat ARJ21-700, is pictured in front of a hangar of the Commercial Aircraft Corp of China (COMAC) on Dec 30, 2013 in Baoshan District, Shanghai. [Photo / dfic.cn]

China's first domestic regional jetliner will go into commercial operation in 2015, with the first two ARJ21-700 aircraft intended for commercial service rolling off the assembly line on Monday.

The dual-turbofan planes will be delivered to Chengdu Airlines Co Ltd by the end of 2014, assuming the airworthiness certification process goes smoothly.

Chinese technicians examine one of the pairs of China's first domestically produced regional jets, the 90-seat ARJ21-700, at a hangar of the Commercial Aircraft Corp of China (COMAC) on Dec 30, 2013 in Baoshan District, Shanghai.[Photo / dfic.cn]

"Chengdu Airlines will put the planes into service in early 2015," said Wang Shenghua, a supervisor at the airlines.

The jets have a two-class configuration, with eight seats in business class and 70 in economy class.

Commercial Aircraft Corp of China Ltd previously assembled four ARJ21-700 jets for testing.

Another three planes for commercial operation will be assembled next year, according to the manufacturer's plan.

However, the jetliner still lacks certification five years after having made its maiden test flight.

"We expect to get the airworthiness certificate from Chinese authorities in 2014," said Zheng Wen, deputy director of the ARJ21-700 program.

Zheng said the jetliner has already passed about 70 percent of the certification inspection. The four test aircraft have completed more than 2,200 trial flights lasting a total of 4,200 hours.

The United States Federal Aviation Administration is also involved in the certification process, and the plane has passed about half the items on the FAA's list.

But some difficult items, such as extreme weather testing, are still pending. Those tests lie ahead in 2014.

It's the toughest time for the ARJ21 now, said Wu Xingshi, a member of the State Council's large passenger aircraft program expert advisory committee.

Lack of working experience among staff is the biggest challenge, Wu said.

The average age of staff members at the Shanghai Aircraft Design and Research Institution, the main research subsidiary of COMAC, is only 33 years.

"It is a young team, but they do not have another alternative, except for working step-by-step," Wu added.

China's regional jet market is promising, as air traffic demand is growing faster than the regional aviation fleet.

Planes with fewer than 100 seats only account for 8 percent of China's civil aviation fleet. Governments at various levels have launched policies, including direct subsidies for airlines and airport construction, to encourage regional aviation.

China's regional aviation market will experience fast growth in the next 20 years, the Aviation Industry Corp of China has forecast.

Embraer SA, the world's largest regional jet manufacturer, said that the Chinese market will need 1,005 new regional jetliners with capacities of 61 to 120 seats by 2031.

COMAC already has 252 ARJ21-700 orders, primarily from domestic carriers.