The CFM56-5B engine equipped with the double annular combustor (DAC) has had a successful entry into service on the Airbus Industrie A321 with Swissair, maintaining the inherent reliability of the CFM56 family while reducing NOx (oxides of nitrogen) emissions by 45 percent compared to engines equipped with a single annular combustor.
The engine is produced by CFM International, a 50/50 joint company of Snecma (Safran Group) of France and General Electric of the United States.
Swissair, which took delivery of its first DAC-powered A321 in January 1995, is currently operating a fleet of five A320/A321s and is scheduled to take seven more A320/A321 aircraft by year's end. Austrian Airlines, which launched the CFM56-5B DAC with Swissair, will take its first A321 later this year. The Swissair fleet has logged more than 2,300 hours and 2,300 cycles to date, providing the exceptional reliability CFM56 customers have come to expect.
CFMI is continuing development work on the DAC that will provide operators with additional value. In September 1995, CFMI is certifying a new fuel system that reduces CO (carbon monoxide) emissions by 23 percent compared to the current configuration. The fuel system includes a new fuel manifold and nozzles, new configuration hardware, and modifications to the engine's FADEC (Full Authority Digital Electronic Control) system. Follow-on developments, set for certification in 1996, will improve combustor durability and will further reduce NOx emissions below current -5B DAC levels.
The CFM56-5B engine equipped with a single annular combustor (SAC) entered service on the A321 in July 1994, and has had an exceptional first year of operations service. The engine has logged more than 25,000 flight hours with no in-flight shutdowns, no removals, and a 99.91 percent dispatch reliability rate.
The engine, which is offered at five thrust ratings ranging from 22,000 pounds (98 kN) to 32,000 pounds (142 kN), is offered on the A319, A320, and A321. The SAC and DAC engines are operationally interchangeable as a shipset and, thus, customers have the option of specifying either combustor configuration for the CFM56-5 engines.