On Friday, when COMAC's C919, China's first homebuilt passenger plane, took off from, and then landed safely at, Shanghai Pudong International Airport, it not only completed its first test flight successfully but marked a major milestone for the Shanghai-based Baosteel Special Steel Co Ltd.

For, the C919 used landing gear made by Baosteel Special Steel, also known as Baosteel, which is now the first Chinese supplier of such hardware for passenger jets.

"It is the first time that the 300M steel researched and produced by the company is used in the production of landing gear in China and it shows we have made a breakthrough in this sector," said Zhao Suwu, a senior engineer from Baosteel Special Steel.

"Baosteel Special Steel's landing gear improves greatly China's steel and high-end special steel metallurgy expertise, which has been recognized globally," said Yang Zhiyong, director of the Special Steel Institute,which is part of the Iron and Steel Research Institute.

It also marks the first global foray of Chinese makers of high-end special steel and high-end aviation parts, Yang said.

Landing gear, being the largest and heaviest steel part of an aircraft, is critical as the whole weight of a plane rests on it and it should be able to withstand strong impact during landing.

Special steel that is used to make landing gear is difficult to produce. Standards are exacting to ensure the hardware's stability, impact resistance and fatigue resistance, Zhao said.

The amount of homemade alloy used in the C919 is not much because Chinese special steel and alloy makers' research, quality control and cost control processes are not as mature as foreign competitors', according to a report in China Metallurgical News.

"Steel accounts for only about 10 percent of the whole weight of the jet, so as to reduce weight and save energy. Most of the materials in the plane are alloys and nonmetals," said Yang.

Baosteel Special Steel and Fushun Special Steel Shares Co Ltd, in Liaoning province, are the only two certified domestic steel suppliers for jumbo aircraft, compared with four foreign players, including India's Tata Group and US major Carpenter Technology Corp.

However, COMAC's decision to use Baosteel Special Steel's landing gear is bound to help develop China's aviation steel segment.

After 60 trials for industrial-scale production, the company has developed a homegrown process spanning the whole chain for special steel manufacturing technology for the C919, said Zhao. The research and development process lasted more than seven years, she said.

Over the years, China's steel makers had been blocked from becoming qualified suppliers to aircraft makers and hence have been eager for their big break in the aviation steel segment.

HBIS Group Co Ltd provides high-end steel materials for the die forging machine that makes the C919 landing gear. COMAC's component platform uses modular design,which means each supplier can be replaced.

The China Metallurgical News report quoted a COMAC expert: "It's only a matter of time before China's domestic materials replace the imported ones, given the improvement in the quality of Chinese suppliers' products and their cost control."

Zhang Yu contributed to this story.