China’s COMAC C919 Faces A New Mathematical Headwind

China’s attempt to compete with Airbus and Boeing in the single-aisle twin-engine airliner market has suffered another blow after COMAC engineers miscalculated load factors. Four people familiar with the development of the plane told Reuters that Chinese engineers sent the wrong mathematical data to the engine manufacturer CFM International.

Bad math leads to C919 delays. Photo: Ken Chen Wikimedia Commons

Now according to inside sources, the engines and their housings may need to be reinforced at COMAC’s expense.

The C919s progress is well behind schedule

Already at least five years behind schedule, the state-owned Commercial Aircraft Corporation (COMAC) is struggling with a series of technical issues that are delaying test flights.


While delays almost always happen in complex aircraft development programs, the inability to move the C919s progress is being seen as a potential embarrassment for China.


Designed to seat up to 168 passengers, the C919 already has orders from 20 customers. While the price tag of the jet has still not been released, it is thought to be around 30% less than the price of an Airbus A320neo or a Boeing 737 MAX. 

The trouble China will have in selling the aircraft will come down to an assumption that Chinese made products are inferior to their western counterparts.


All the technical glitches and delays with flight testing mean that COMAC has completed only 20% of the time the aircraft needs in the air to get final approval from the Chinese Civil Aviation Administration (CAAC).

COMAC and CFM International refused to comment

When speaking to the Chinese state media late last year, a representative of COMAC, Ying Yang said he expected the C919 to be certified in two to three years. Prior to this, the planemaker had set the end of 2020 for certification with the first deliveries in 2021.

When Reuters contacted both COMAC and CFM International for comment, neither responded with information regarding the aircraft’s development.

COMAC wants the C919 to compete with Airbus and Boeing. Photo: Kentaro Lemoto Wikimedia Commons

From what Reuters understands, COMAC has still not sent the correct calculations to General Electric and Safran. This is despite the engine maker needing the information to ensure that the engines can handle heavy loads.

One of Reuters’ sources told the international news organization that, “things do not always work out as planned, but I hope COMAC would slow down a bit and try not to rush things, otherwise there will be tons of issues later on.”

Even though China has been sending people into space for nearly 20 years, the engine miscalculation illustrates COMAC’s lack of experience in building commercial aircraft. 

As well as the engine problems, COMAC has also come across cracks in the horizontal stabilizers of some of the first few aircraft they built. There have also been gearbox problems that have forced the engines to shut down during test flights along with inspections that have discovered cracks and leaking oil.

The gearbox issues are related to unexpected vibrations that have added to the timeframe problems and could prove costly to resolve.

All of this is coming at a time when industry forecasters are predicting a slowdown in the demand for new aircraft due to geopolitical tensions.

The Chinese had made the C919 a pivotal part of its ‘Made in China 2025’ initiative to help the nation become more self-sufficient.

China can force its own airlines to buy the C919

Looking at it realistically, the C919 will be a success despite all its teething problems. This is because the communist Chinese government can force its own airlines to purchase the aircraft, rather than Airbus or Boeing models. 

Chief analyst of DCA Chine-Analyse Jean-François Dufour agrees when he says:

“The C919’s real mission is to conquer a domestic market dominated by its two foreign competitors. Ten to 15 years from now, a next-generation C919, or other models developed by COMAC, may become real competitors on the global scene.”

China can force its own airlines to buy the C919. Photo: Getty

The C919 is still a work in progress, but it will be nice to have another competitor to the big two offering a reasonably priced 100 plus seat aircraft.

Would you be worried about flying on a Chinese built C919, or do you think once the engineers sort out all the issues it will be as safe as any other aircraft in the sky?

Please let us know in the comments.


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Starting up a new commercial aircraft manufacturer is clearly tough, but look at the eventual successes of Embraer and of Bombardier with the C Series. It’s certainly possible to come out with a world class product. Take the time needed to get it right. It’s hard to overcome an iffy rep, otherwise we’d be flying on Russian commerical jets.


It is not just rep – Interjet tried to use SSJ100 and it was a disaster. Only five out of 22 are actually flying and the rest is grounded due to lack of spare parts. Sukhoi might be able to design and manufacture a new aircraft, but logistics of actually keeping them in the air is clearly beyond their capacity.


This is why there are governing bodies, like the FAA, in place to protect the consumer from less then stellar products. When the system breaks down, the result is people die, a la 737 Max


“Chinese engineers sent the wrong mathematical date to the engine manufacturer” I think you mean they sent the wrong data, not date.

David Simon

Good looking plane, I’ll let someone else be the beta tester…


Funny – that’s the same thing I say about the Max!


What a Ugly Plane..!

Richard Johnson

If China forces their airlines to buy this plane and some other small communist countries that China influences this could be a ton of sales for this plane. Could really hurt airbus and boeing in the future.

Gerry S

I will fly on this C919 airplane, no problem. It just has to be in ten years or so and after I am reasonably certain that it will not fall from the sky. By that time, however, C919 will be much like the B717. Past its time. Boeing and Airbus will have new state-of-the-art entries out there. No way COMAC can compete.

Gerry S

@Jim: Notable difference between COMAC and Embraer/Bombadier. Before Embraer built their ERJs they had built (on their own) a/c such as EMB-110

Gerry S

……and EMB-120. Short haul twin props. Bombadier built their Dash 7 and Dash 8. These were designed and built by the manufacturers. Both went on to build regional jets with Italian and American assistance. COMAC is different. They reverse-engineered other builders airplanes. Now C 919 is new to them. The Chinese lack the engineering expertise of engineer's who design a/c from scratch. Making a copy of something is less difficult that making an original. This will be a learning experience for the Chinese and they will master it, but not real soon.

Riaz Hassan

Not at all worried. Chinese technology, including aircraft technology, is already about at par with the best anywhere. Considering the teething problems encountered by some famous manufacturers and the fact that their airplanes still suffer accidents and crashes, fears about Chinese built ones are misplaced


China will have to buy the best state of the art airplanes like the A220 and A320/321 for a long time.


Considering that China hacked the manufacturers and so many of the worlds airline industry to lazily make the planes cheaply without much effort.
No one should support them after what they have done.


time, lots of money & accident-free operations over a decade or so – may find global buyers – but in the final analysis Airbus & Boeing will continue to rule the roost for many a decade yet!

John Fretwell

Lovely article. Not turbo prop though think they were turbo compound piston engines


When the Airbus A380 was being developed, there was a goof up in matching large parts made in one plant/country, to those made in another plant & country. I don’t remember the details but that problem had delayed a380 quite a bit. And who can forget the huge goof-up between NASA’s two control stations which resulted in a Mars bound spacecraft, costing US$190 million being lost forever! All because one lab was using metric units and the other was using US Standard (British) units!!

Gerry S

@JohnF: Nah! EMB-110 had two PT6As wheras EMB-120 had two PW100s. Pure turboprop.