(Yicai Global) Feb. 14 -- The Commercial  Aircraft Corp. of China is preparing three more prototypes of the  country's first domestically produced passenger aircraft to conduct  their maiden flights this year in the run-up to start delivering  hundreds of piled-up orders in three years.

Test flights for three narrow-body  twinjet C919s are expected to take place by year-end, state-backed CCTV  Business Channel reported. The prototype no. 104 has entered its final  assembly stage, the 105 is undergoing the assembly of major components,  and the main components of the 106 are in production.

"It takes three to four years to conduct  test flights, forensics, design and experimentation," said Wu Guanghui,  the chief designer of the plane, adding that the first finished product  is expected to be delivered to China Eastern Airlines in 2021.

The first C919 spread its wings for the  first time in Shanghai on May 5, 2017. The aircraft model has received  815 orders from 28 customers at home and abroad. The Shanghai-based  planemaker has completed initial tests with two more prototypes,  numbered 102 and 103, which are undergoing modifications.  

Editor: Emmi Laine