Li Xianghong on his self-built plane. [Photo from Li Xianghong's Sina Weibo account]

Three years later, the 46-year-old Boeing engineer made his first international flight from Seattle to Canada on the same aircraft in early July after flying safely for over 300 hours.

Li's affection for flying dates back to his childhood in Zhuzhou, central China's Hunan province, when his father was a bomber pilot. Visiting his father's army and watching him in the sky was one of the most memorable moments of his happy childhood, sowing a love for flying deep in the little boy's heart.

But his father objected when Li decided to apply for pilot school after graduating from high school due to age and safety concerns. He wanted his son to learn plane construction and design.

The career life of a pilot is very short but a plane engineer could still work into his 60s even 70s, according to Li's father Li Yougen.

Respecting his father's will, Li entered the applied mechanics department of Beijing University of Aeronautics and Astronautics. He went to America for further study in 1995 and became an engineer at Boeing Company after graduation.

However, he never forgot about his aspiration to fly. In 2007, he got a private pilot license.

"I planned to build a plane myself considering I had to rent one every time I wanted to fly," he said.

After over one year of preparations and study, Li kicked off his DIY project in his garage in April 2011 and completed the seemingly impossible mission on May 27, 2014, after spending 1,900 hours and $90,000.

"Security remains the key issue of the building process. Any minor component problem could lead to accident in the air and pose threat to human life," he said.