The collaboration between UTC Aerospace Systems, the aerospace systems business unit of US-based United Technologies, and China's AVIC Electromechanical Co Ltd, was created primarily to produce electronics for the C919.

"The site has been manufacturing electronic power-distribution panels for its legacy program for well over a year," said Hou Xiaofan, UTC's general manager in China. It has been also making other components for customers in North America.

But UTC Aerospace System is also providing other systems for the C919, including fire protection, cockpit control and de-icing.

"We are sharing our experience in system integration with COMAC," Hou said.

Some foreign suppliers have transferred their technology completely to their joint ventures in China.

Aviage Systems, established by China's Aviation Industry Corporation and the US' General Electric in 2012, is providing various avionics packages for the C919, including those using GE's flight-management, flight-deck display and flight-recording systems.

Alan Jones, Aviage's president and CEO, said as part of the original agreement, GE transferred the IP for a jointly developed computer system and integrated modular avionics technology to Aviage.

"Different from other joint ventures, Aviage Systems owns the core technology. We are developing integrated modular avionics architecture which is considered the best in class in the industry today, " said Jones.