The CFM56-7 is performing exceptionally well in the Boeing Next-Generation 737-700 flight-test program, meeting or exceeding all expectations in terms of reliability, operability, and performance. The four-aircraft, 2,200-hour 737-700 flight test program is expected to lead to aircraft certification in September and entry into service in October with Southwest Airlines.
The CFM56-7, which powers all models of the Next-Generation 737 family, is produced by CFM International, a 50/50 joint company between Snecma (Safran Group) of France and General Electric of the United States.
The CFM56-7B-powered 737 began flight tests in early February and had logged more than 600 flight hours through May. The engine portion of the aircraft certification program has been completed with no problems, and the -7B is meeting guarantees in all areas. Some of the tests Boeing has conducted to date include: aircraft stability and control, fuel burn and performance, operability, acoustics, equipment vibration, flight loads, and stall handling. The aircraft has also successfully completed high altitude, hot day testing.
In March, the 737-700 set a new 737 altitude record at 41,000 feet; current 737s have a maximum altitude of 37,000 feet. Boeing's test pilot noted that "the climb performance of the engines was excellent."
The next phase of the program will be launched this summer when the new 737-800 begins flight tests in preparation for entry into service in 1998. First flight of the smaller 737-600 is scheduled for next January, and that aircraft will enter service in 1998 as well.
Although the CFM56-7 was certified last December, CFMI is conducting on-going engine tests. An engine equipped with CFMI's double annular combustor (DAC) has completed thermal survey and over temperature tests, in addition to the Full Authority Digital Electronic Control fault test, at GE facilities in Ohio. Another DAC engine began the certification block test at Snecma earlier this month. In July, the DAC engine will begin a 40-hour operability demonstration flight test program on GE's modified flying testbed in preparation for certification and entry into service with Scandinavian Airlines System (SAS) on the 737-600 in 1998. SAS launched the -7 DAC in 1995 with an order for 41 firm, 35 option aircraft.
In addition to the DAC tests, CFMI has successfully completed the 3,000 "E" cycle test to qualify the CFM56-7 for eventual extended-range twin-engine operations approval by the U.S. Federal Aviation Administration. The rigorous test involves running the engine through 3,000 simulated in-service cycles - takeoff, climb, cruise, and descent - in addition to continuous four-hour cycles to simulate an aircraft diversion on a single engine.
The demanding test program to which CFMI subjected the CFM56-7 is designed to ensure a service-ready engine at entry into service. The resulting reliability of the engine has facilitated a very smooth flight-test program and has been a major contributor to Boeing's ability to set new records for flight-test hours per month in its 737 flight-test program.
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