3 Time On Wing (TOW) upgrade package has received engine certification from the U.S. Federal Aviation Administration and French Direction Gnrale de l'Aviation Civile. Launch customer Southwest Airlines is set to take delivery of its first 50 kits this year.
U.S.-based Southwest launched the TOW upgrade in 2001 with a $300 million order for 300 upgrade kits. In addition to the 50 kits to be delivered in 2002, the airline will take delivery of 100 kits each in 2003 and 2004, with the final 50 packages delivered in 2005.
The CFM56 product line is produced by CFM International (CFM), a 50/50 joint company between Snecma Moteurs (Safran Group) of France and General Electric of the United States. More than 4,200 CFM56-3 engines have been produced for the Boeing 737-300/-400/-500 series, and CFM anticipates potential sales of about 1,000 engines for this upgrade.
The CFM56-3 TOW package completed an exhaustive development and certification program, including more than 400 hours of ground testing and a 50-hour flight test program.
In May, CFM completed final certification icing tests at a unique U.S. Air Force facility, the McKinley Climatic Laboratory at Eglin Air Force Base, Florida. An unusually warm winter had prevented CFM from completing all of the required icing test points at GE's Peebles test facility in Ohio earlier in the year. The McKinley facility is capable of reaching and maintaining the necessary temperature of about 8? F. A portable rig developed by Peebles test engineers was used to create the ground fog conditions that enabled the engine to complete the remaining test point. The engine was installed on a 737-500 aircraft leased from Southwest Airlines.
In February, Boeing Airplane Services conducted the flight test program at its facilities in Seattle, Washington, on a 737-400 aircraft leased from Alaska Airlines. Two different enginessequentially installed in the No. 2 positionwere used to evaluate performance and operability characteristics throughout the flight envelope. CFM also completed a 150-hour block test at Snecma (Safran Group) facilities in France. As part of certification requirements, the engine was completely disassembled for inspection by regulatory agencies. Despite the grueling nature of this test, the hardware was in like-new condition.
The TOW upgrade, which is installed during normal overhaul, features advanced three-dimensional aerodynamics (3-D aero) in the high-pressure compressor and new high-pressure turbine hardware. It provides significantly better fuel efficiency, through a 1 percent improvement in specific fuel consumption, and up to 15 degrees additional exhaust gas temperature (EGT) margin. The additional EGT margin helps reduce maintenance cost through longer on-wing life, versus the current configuration.
CFM56-3 engines average 16,000 hours on wing before requiring an initial shop visit and about 10,000 hours after overhaul. The TOW core upgrade will improve post-overhaul time on wing by as much 1,500 to 2,000 hours.
Turbine improvements include new nozzle and shroud materials, a new blade coating, and improved cooling. These changes extend component life and will lower scrap rates and repair costs by as much as 50 percent.