China's first domestically produced large passenger aircraft, C919, has successfully completed key tests on its engines, marking the final stage of its testing phase. Production for use of the C919, the Commercial Aircraft Cooperation of China (COMAC), is scheduled for sometime of next year. 21 foreign and domestic customers have already placed over 500 orders for the jet. COMAC estimates the potential market of C919 is worth more than 650 billion yuan (100 billion US dollars).[Photo from Sina Weibo]