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By Bjorn Fehrm

April 24, 2025, © Leeham News: We started looking at the future COMAC C929 widebody 10 days ago. The C929 development has gone through a number of challenges, the first being how to structure the cooperation between China’s COMAC and Russia’s United Aircraft, with the latest being what engines to use for the aircraft.

The first problem was solved by COMAC deciding to go it alone, whereas the last problem around engines has no definite solution yet.

Figure 1. The C929, a new COMAC widebody that shall complement the C919. Source: COMAC.

Summary:

• The C929 airframe is taking form with detailed design having started, according to COMAC.
• The engine side is less settled. The likely engine is the Chinese CJ-2000, a 78,000lbf development of the CJ-1000A engine aimed at the C919.
• We apply the CJ-2000’s likely performance to the C929 airframe and use our Aircraft Performance and Cost Model (APCM) to predict the C929’s operational performance.

The C929 operational performance

The C929 is a Boeing 787-9-sized widebody, and we described its drawn-out development in the C929 start article on April 14. The size of the fuselage is 1 meter longer than the Boeing 787-9 at 63.8m. Seating capacity will be similar at 280 to 290 seats in a typical two-class long-range configuration (787-9 then has 290 seats).

We evaluate the C929 with our Normalized 290-seat two-class cabin, which has 40 lie-flat Business-class seats at 60-inch pitch and 250 Economy seats at nine abreast and 32-inch pitch.

As we described in the last article, the problem area for the C929 is the engines. In the present political climate, we don’t think Western engines are feasible, and the Russian development of an engine for this size aircraft is probably trailing the Chinese development of the Aero Engine Corporation of China (AECC) widebody CJ-2000 engine by now.

We therefore assume the CJ-2000 engine, which has data similar to the Rolls-Royce Trent 7000 used on the A330neo. We will examine the C929 performance when the CJ-2000 has the same efficiency as the Trent 7000. Then we describe what happens if it has 5% less efficiency than the Trent 7000.

In the last article, we wrote that the wing is 63.9 m wide, which is 3.8m wider than the 787-9’s wing (Figure 2). The fuselage is 17cm or 6.7 inches wider than the 787 fuselage, for a standard comfort nine abreast in the economy section (the 787 was designed as a comfortable eight abreast and a tight nine abreast cabin).

Figure 2. The C929 (magenta) with the 787-9 on top (blue). Source: Leeham Co.

We assume the structure is made using the classical Composite Prepreg plus Autoclave process, which is currently the most well-known and certified composite process. COMAC and its AVIC structure supplier would use this process as it’s the only one that could give them a straightforward structure certification process outside China.

The systems would be similar in supplier and function to the C919 systems, given that the suppliers can get permission to be fitted to a new Chinese Civil transportation aircraft. Many of these systems are produced in China by a Joint venture company between a Western supplier and a local partner.

Performance estimation

We use the weight estimation module in our Aircraft Performance and Cost Model (APCM) to predict the C919’s empty weight. With a wider fuselage and wing, it would be about 3.5 tonnes heavier than a similarly configured 787-9.

With a 245-tonne Maximum Takeoff Weight, MTOW, it would then have a maximum range of 6,150nm or 11,400km with our standard airliner reserves of five percent underway fuel markup, a 200-nm alternate, and 30 minutes of circling at the alternate.

COMAC claims 12,000km or 6,480nm, but we think this is optimistic with the chosen long-range cabin. The above is with a CJ-2000 that would have the same efficiency as the Trent 7000. Should it fail the fuel consumption by five percent, it would mean a maximum range of 5,800nm.

The 787-9 with the same 290-seat long-range cabin and rules would have a range of 7,300nm. The main reason for the range difference is the difference in MTOW, where the C929 is said to have a 245t MTOW and the 787-9 254.7t. The extra 13.2 tonnes of fuel gives an additional 1,300 to 1,500nm range.

Operating costs

Estimating the C929 operating costs is difficult as long as the engines’ fuel consumption and maintenance costs are not defined. We give the results from the performance model for a nominal engine that would be similar in fuel consumption to a Rolls-Royce Trent 7000.

We can’t estimate the maintenance costs for the first widebody engine from a manufacturer, Aero Engine Corporation of China (AECC), with zero experience operating commercial aircraft engines, let alone engines in this trust class. Any maintenance costs charged to an operator would be as much a policy decision as a commercial decision.

The fuel costs for a flight close to the C929’s maximum range would be 6% higher for the C929 compared to a 787-9 flown the same distance. We then used our airliner rules described above for both with the Passenger plus bags at 100kg.

Cash Operating Costs, COC, are difficult to predict. Crew costs when operated by the same airline will be similar. Maintenance costs would be 100% dependent on the COMAC and AECC policies for cost coverage for the initial operation phase for a new aircraft and engine type (costs usually are higher in the first years of aircraft deliveries, before a new aircraft settles in at mature costs).

Direct Operating Costs, DOC, suffer the same unpredictability regarding COMAC and AECC net pricing policies, as these are state-owned companies, and there is no transparency into their operational results when selling these aircraft to the market.