CFM International's new CFM56-7 engine for the Boeing 737-600/-700/-800 series began flight tests in January on board a modified Boeing 747 flying testbed at GE Aircraft Engines test facilities in Mojave, California.
The CFM56-7 is on track for engine certification in October 1996, and first flight on the new 737 in early 1997.
The 747 testbed flights will run through March 1996 and encompass a total of about 20 flights (100 flight hours), during which the engine will demonstrate flight worthiness and flight safety. Tests will include takeoff and in-flight performance, operability evaluations, air starts and engine stability, and fan stress and inlet distortion test.
The CFM56-7 has performed well in more than 600 hours of ground development and certification testing. The CFM56-7B engines on test have successfully completed performance and operability tests, engine acoustics tests, low pressure turbine and high pressure compressor airfoil stress tests, cross wind testing, and fan and booster stress tests. Vibration endurance and the 150-hour block test are in progress.
Ground performance tests demonstrated that specific fuel consumption and exhaust gas temperature margins are on target. In addition, a 4 percent thrust margin at hot day conditions to the maximum thrust rating of 26,300 pounds was demonstrated.
CFMI has also successfully completed three fan blade-out component tests. As required, only one blade separated in each event. However, CFMI is thickening the fan casing to improve fan containment capability. Similarily, the engine accessory gearbox casing and attachment pads are being reinforced to withstand higher fan blade-out loads. In addition, Boeing is adding more containment capability to the inlet in the unlikely event that fan blade pieces are ejected forward of the engine containment ring. All of these changes will be incorporated into the engine prior to the blade-out certification test scheduled for April 1996.
Large bird ingestion component testing has been completed and the engine met all certification requirements.
CFMI is working with Boeing on modifications and design changes that will further enhance durability and reliability. For example, the material in the exhaust nozzle has been changed from titanium to INCO for improved durability and life.
Since the CFM56-7-powered 737 program was officially launched in late 1993, 13 airlines have placed orders for more than 350 firm and option aircraft, representing the fastest accumulation of orders for any commercial jet in history.
CFM International is a 50/50 joint company of Snecma (Safran Group) of France and General Electric of the United States.