C919 large aircraft, shining Jiangsu elements

C919 is the first jet trunk airliner developed in accordance with international airworthiness standards in China, and obtaining the model certificate is an important milestone
in the development of China's large aircraft industry.
The C919 jumbo first flew in 2017 and is expected to deliver its first aircraft
by the end of the year.
As a pearl made in China, what are the Jiangsu scientific and technological forces behind the C919 large passenger aircraft?

Create "extreme challenges" to validate aircraft ice resistance

In 2017, the first aircraft of the C919, which carries the dream of China's aviation manufacturing industry for generations, was successfully test-flowned
.
Since then, C919 has entered the "service" of civil aviation with high expectations
.
But a key step in getting the C919 into operation is airworthiness forensics
.

Airworthiness forensics is about subjecting an aircraft to extreme challenges" to verify aircraft performance
.
Every successful test flight means it is one step closer to the delivery of airworthiness permits
.
Among them, the determination of the critical ice type based on the FAR25-121 amendment for the first time in China fills the gap
of the domestic simulated ice anti-icing test.
Behind this is the hard work of a scientific research team of Nanjing University of Aeronautics and Astronautics (hereinafter referred to
as "China Southern Airlines") from scratch.

Since 2019, Professor Zhou Guangming and Professor Cai Deng'an of China Southern Airlines have led the team to open the C919 large passenger aircraft simulation ice test flight project
.
"In view of the particularity and complexity of the C919 large passenger aircraft test ice type, the team carried out multi-faceted research, further upgraded on the basis of the ARJ21 aircraft, and greatly improved the quality and process implementation efficiency of the simulated ice type by introducing a number of innovative work such as 3D printing ice type scheme and large particle roughness band
, and created a precedent for simulated ice modification and test flight of sandwich composite materials in China.
" Zhou Guangming said
.

In order to meet the urgent needs of the great development of airworthiness technology of large passenger aircraft, China Southern Airlines has set up a reliability and airworthiness technology research center
.
"The central team is an excellent discipline echelon of 'Qinglan Project' in Jiangsu Province, and the team's main research directions include aircraft safety design and verification technology, large aircraft airworthiness verification and verification technology, aircraft continuous airworthiness and operation support technology and other advantageous disciplines
.
" Sun Youchao, director of the center and professor of China Southern Aviation Civil Aviation College, said that the center has formed a distinctive feature and technical advantage
of "civil aircraft + civil aviation + airworthiness".

According to reports, the team's fruitful research results in related airworthiness technology have been applied in the airworthiness verification of C919 large passenger aircraft, and dozens of provincial and ministerial and model development projects have been undertaken to complete dozens of provincial and ministerial level and model development projects
such as C919 large passenger aircraft safety and C919 large passenger aircraft airworthiness certification regulations and normative documents.

Innovative technology and materials, to create a "good body" and "clairvoyance"

The C919 large passenger aircraft obtained the model certificate, and the precision laser welding technology developed by the Nanjing Advanced Laser Technology Research Institute (hereinafter referred to as the "Nanjing Laser Institute") located in our province has made a contribution
.
"The project result of our leading research, 'Dual Beam Double-Side Synchronous Welding Technology', was successfully applied to the wall panel structure
of the fuselage of the C919 large airliner.
" Tang Yifeng, project manager of Nanjing Laser Institute, said
.

"The fuselage siding structure of the C919 large passenger aircraft is often referred to as the 'skeleton skin structure.
'
" Tang Yifeng told reporters that simply put, there are long trusses inside the fuselage wall as a skeleton support connection, and the outside is covered with a layer of metal plates to form a common action system
.
"This meets the requirements of light weight and high strength of aircraft manufacturing materials in the
aerospace sector.
"

The materials for manufacturing aircraft are generally lightweight materials such as aluminum alloy and magnesium alloy, but pores and cracks are prone to occur during the welding process, and the stress is large and the deformation is difficult to control
after welding.
Tang Yifeng introduced that through the dual-beam double-side synchronous welding technology, they improved the deformation of the welded joints of the long weld, and improved the strength, reduced the manufacturing cost, and had the advantages
of good air tightness, high fatigue performance, high production efficiency, easy to achieve automation and flexibility.

During the take-off, cruise, entry and landing of the C919 large passenger aircraft, an integrated surveillance system to ensure flight safety is indispensable
.
The system was developed by AVIC Leihua Collins (Wuxi) Avionics Equipment Co.
, Ltd.
after five years and was successfully completed
in November 2020.

"As one of the core avionics systems of the C919 large passenger aircraft, the integrated surveillance system is known as the 'clairvoyance' of the aircraft, which can provide real-time and accurate surrounding flight environment information for pilots during take-off, cruise, entry and landing, and provide safety guarantees
.
" Yu Chaopeng, an engineer at China Airlines, said that if the engine is compared to the "heart" of the aircraft, then the avionics system can be called the "brain and central nervous system", and the integrated monitoring system is equivalent to the "ear" and "eye", which can help the large aircraft to detect the situation
600 kilometers away.

Ensure excellence, for large aircraft to do a good job

In the workshop of Nanjing Hangpeng Aviation System Equipment Co.
, Ltd.
, part of the aviation system of the C919 large passenger aircraft was released
here.
According to the person in charge of the company, the fuel hydraulic system project of AVIC Parker's large civil airliner is a joint venture between the Nanjing Electromechanical Hydraulic Engineering Research Center of China Aviation Industry Jincheng and Parker Aerospace Group of the United States, and
the main manufacturers use aircraft fuel systems, inerting systems and hydraulic systems.

There is a long cylindrical tube in the workshop, which is the hydraulic accumulator
on the aircraft.
"Generally, an aircraft should be equipped with three or four hydraulic accumulators, which are installed in landing gear, hatches, etc
.
" The person in charge said that according to the design of the parent company, they processed, assembled and tested
at the factory in Jiangning, Nanjing.
After the mass production of the C919 large passenger aircraft, they will become the first-tier supplier
of their fuel hydraulic systems.

Jiangsu Meilong Aviation Parts Co.
, Ltd.
is located in Zhenjiang, Chairman Liu Shunlong said excitedly: "Twelve years of struggle, the final score of Huazhang
.
I was thrilled to hear that a large aircraft had obtained a model certificate
.
A supplier of COMAC systems in China, Meilong undertook the C919 main cargo compartment interior and sub-cabin plate work bag task
.
In recent years, in order to accelerate the development of serialization, Meilong has undertaken a number of new research and development tasks, and made unremitting efforts to achieve breakthroughs in key materials and component innovation! ”

Gao Zhiqiang, chairman of the board of directors of Aerospace Seahawk (Zhenjiang) Special Materials Co.
, Ltd.
, could not hide his joy in an interview with reporters: "After winning the bid, China Aerospace Science and Industry Group built Seahawk special materials, the purpose is mainly to support
large aircraft.
"Seahawk Special Materials is one of the nine major body structural parts suppliers of COMAC C919 large passenger aircraft, which undertakes the development of rear fuselage's rear section, front section, aileron and vertical tail composite parts, accounting for nearly 50%
of the composite materials used in C919 passenger aircraft.