China's aerospace ambitions became airborne on 5 May, as its C919 narrowbody successfully completed a 1h 19min first flight. In a move of unprecedented transparency, the maiden sortie was broadcast live on Chinese television, with a camera positioned behind chief pilot Cai Jun.
Despite the lack of sunshine and blue skies, spirits were undampened. As aircraft B-001A took off from an overcast Shanghai, the crowd broke into cheers and applause. The aircraft flew with its landing gear extended throughout the flight, and reached a maximum altitude of 10,000ft.
All appeared uneventful and Cai later confirmed that the CFM International Leap-1C-powered jet performed normally throughout. Comac chairman Jin Zhuanglong said all 15 parameters earmarked for the first flight were tested and declared the sortie a success.
FIRST STEP
The achievement of a maiden sortie represents a major milestone for the C919 programme, seven years after its launch. It is, however, merely the first step in a certification campaign that will require 4,200 flight hours. Comac will use six prototypes to log an estimated 2,282 flights where it will strive to complete 729 test modules, says flight-test manager You Li Yan.
The manufacturer can expect challenges during the test campaign. After all, just preparing the C919 for is first flight took more than a year since its roll-out in November 2015. During this time, Comac has been busy integrating the aircraft's different systems.
Alan Jones, chief executive of Sino-US joint venture Aviage, which is providing a number of systems for the twinjet, says a series of tests and approvals were conducted during the past 18 months, not just on individual work packages such as its avionics and engines, but on the aircraft as an integrated whole.
"The challenges that surfaced were expected ones, where different suppliers were working to different versions of the specifications and they had to evolve in order to refine how this system connected with the next one," says Jones.
"That came together in Q3 and Q4, and in the last five months. It's just about working through paperwork and making sure all the assumptions for safety have been substantiated, checked, verified and signed off."
NEXT MILESTONE
While Comac has said that its test programme will span 4,200h - at least 1,000h more than an established manufacturer would require for a clean-sheet design - it has said little else regarding the C919's timing. Sources tell FlightGlobal that evaluations will take place at three different bases across the country: at Comac's flight-test centres in Shanghai and Dongying; and at an AVIC facility in Xian.
A total of six aircraft will be used for the validation effort, with three allocated to Xian, including the very first example.
COMAC
"Ferrying the first prototype to the Xian flight-test site for regular flight tests will be the next big milestone to watch," says one source, adding that the event is scheduled for September. The second flight-test article, however, will be based at Dongying in Shandong province.
Comac's C919 vice-chief designer Fu Guo Hua says the second prototype is in final assembly, with roll-out targeted within 12 months; aircraft 103 and 104 are scheduled to complete final assembly in 2018.
SPLITTING THE WORK
You says the first prototype will largely test the aircraft platform and its functionality, as well as its landing gear. The second prototype will focus on engines, auxiliary power unit, and fuel-system tests, but will also perform extreme weather trials.
Aircraft 3 will have a similar evaluation profile as the lead example, while the fourth prototype will focus on tests of the avionics and electrical system. The fifth jet will supplement the avionics tests, but will also be used for trials of the environmental control systems. The final prototype will be in a production-conforming configuration and will be used to assess overall reliability, says You.
Performing the flight tests is one thing, but being able to do so while complying with the complexities of certification is another. The airframer last year applied for type certification of the C919 with the European Aviation Safety Agency, via its own regulator, the Civil Aviation Administration of China (CAAC).
Comac discloses that EASA has started work on the C919 approval, having visited its Shanghai facility to examine the manufacturing process.
WESTERN CERTIFICATION
The manufacturer's approach to EASA shows that its ambition for the jet is not constrained by China's borders. It also confirms Comac's break from the US Federal Aviation Administration, which has yet to certify the ARJ21 regional jet despite years spent shadowing the CAAC.
To judge by the long list of issues with the late-running ARJ21, Comac has struggled to grasp fully the certification process. Even now, it has still to obtain a Chinese production certificate and Western approval seems even more distant.
Fu says that Comac learnt a great deal from the ARJ21's development and is determined not to repeat any errors. For example, the C919's flight-test fleet is two aircraft larger than the four-strong complement used for the regional jet's certification.
"We are fully using what we have learnt from the ARJ21. In terms of planning, the top management has made the effort to not repeat the mistakes that we made on the ARJ21. We don't rule out new issues cropping up on the C919 since it's a different generation aircraft with different certification requirements and standards," says Fu. "But I believe the C919's flight-test and certification journey will be very different from the ARJ21's."
STARTING FROM SCRATCH
As a new entrant to the market, Comac has had to overcome the challenges that have long since been dismissed by Airbus and Boeing. Engineer Luo Dong Hui says it had to start from scratch and design its own flight-control laws since the technology is heavily protected by existing aircraft manufacturers. But getting those right is critical to aircraft safety.
While Honeywell supplies the C919's fly-by-wire hardware, regulations prohibit any communication about flight-control laws between the two companies.
"We can only give them our requirements and they will meet it. We also tried to find foreign experts in such areas, but because this technology is viewed as key, those in current programmes cannot interact with us. So the help that we received from overseas is very limited. We're relying mainly on public domain materials for research," Luo adds.
Comac worked with 30 pilots, both from China and overseas, to test and validate the control laws it developed. It received positive feedback, but has also incorporated a number of suggested improvements.
"It has been a challenge because it's the first time we're designing this. We started from zero, and we're confident the system is as advanced as the aircraft flying in the market today."
But the flight-control laws are far from the only item that Comac has to develop from scratch. For example, the manufacturer is also working on the C919's flight-control and maintenance manuals.
The Chinese airframer's inexperience is partly a reflection of its young team, where about 75% of employees are under the age of 35. When it was established in 2008, the majority of its employees were either in their first job or close to retirement. It has since hired experienced staff and also foreign talent to fill the gap and mentor their younger colleagues.
CONFIDENCE IN THE FUTURE
Comac, as you might expect, is feeling the pressure. It has not provided any official guidance for the date of the C919's first delivery to launch customer China Eastern Airlines. When pressed, Fu would only say that it should take around three years, but stresses that unforeseen problems could extend the process. He also does not rule out further design changes as flight tests progress.
"This is our own Chinese aircraft and our foundation is not there like Airbus or Boeing. What we're trying hard to do is to resolve whatever issues that we have. We hope people can give us more tolerance. There is a lot of pressure," he adds.
John Liu, Leap-1C programme director, meanwhile expresses confidence in the C919. While the aircraft's engines are similar to the -1A and -1B models that respectively power the Airbus A320neo and Boeing 737 Max, they feature a new thrust-reverser design that will enhance aerodynamic efficiency and make maintenance simpler.
"Comac is very different. They have a different culture and less experience but they are very eager to learn and willing to cooperate. My onsite team works very closely with them, and we have a very good working relationship that really helps to move the programme forward," he adds.
Source: Cirium Dashboard
