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At one stage the biggest aircraft in the world, the Lockheed C-5 Galaxy is still a giant of the skies. The U.S. Air Force has been flying this long-haul cargo aircraft for four decades and plans to keep it in service until 2040. Half of the U.S. Air Force’s 114 aircraft are now being modernized and the obsolete TF39-GE-1C engines are being replaced by the enhanced CF6-80C2L1F variant. MTU Aero Engines participates in this GE Aviation engine program.
The C-5 Galaxy is a heavy logistics cargo transport aircraft developed to provide strategic airlift and logistical support to U.S. combat and supply units. Almost as long as a soccer pitch (75 meters), as tall as a sixstory building (20 meters) and with a huge wingspan (68 meters), this is a uniquely superlative aircraft. Featuring a cargo bay that is over four meters high and almost six meters wide, its large front and rear cargo doors allow simultaneous loading and unloading from two sides. The Galaxy’s cargo bay doors can also be opened unusually wide, permitting outsized equipment to be loaded far more rapidly and tanks and trucks to be easily driven in and out. To further facilitate loading, the parked aircraft can be lowered hydraulically on its landing gear to truckbed height. The Galaxy can swiftly carry out intercontinental transport of up to 150 metric tons of cargo, and can take off and land on relatively short runways.
The cargo floor of the Super Galaxy.
The C-5 Reliability Enhancement and Reengining Program (RERP) was launched by the U.S. government to upgrade its C-5 fleet for the 21st century. Among other things, the program is designed to replace the engines with newer ones—four per aircraft—, make improvements to the avionics including providing a “glass cockpit”, and enhance the electrical and fuel systems, ultimately transforming the C-5 into the C-5M Super Galaxy. The initial conversions have already been completed, and Lockheed Martin delivered the first C-5M to the U.S. Air Force on December 10, 2008. The aircraft is stationed at the Warner Robins Air Logistics Center at Robins Air Force Base in Georgia. Two further aircraft followed and were delivered to Dover Air Force Base in Delaware in February 2009. By the year 2020, the plan is to convert 52 aircraft of the more modern C-5B and C-5C types to the Super Galaxy standard but to exclude the oldest C-5A-type aircraft, which will no longer be updated.
Prior to their delivery to the U.S. Air Force, the three now enhanced C-5M cargo aircraft successfully completed an extensive test flight program in the United States. “Between 2006 and 2008, around 5,200 test points were flown over the course of 1,100 flight hours,” explains Josef Moosheimer, Senior Manager, Program Coordination, GE Programs at MTU in Munich. “The 12 engines achieved a combined total of 7,400 operating hours.” The new CF6-80C2L1F turbofan engines from GE Aviation not only offer around 75 kN more thrust than the obsolete TF39: “They also burn less fuel and are much more reliable, quieter and, crucially, more economical to maintain,” adds Wolfgang Hiereth, MTU’s Director, GE Programs. The U.S. Air Force has ordered 208 engines plus a number of spare engines. In fact, the Super Galaxy’s engines are largely equivalent to the commercial CF6-80C2 with just some minor modifications. “Developing a brand-new engine would have simply been too expensive,” explains Hiereth. “It goes without saying that the CF6-80C2L1F is a state-of-the-art system.”
The GE Aviation CF6-80C2 engine.
When the Galaxy was being developed at the start of the 1960s, the Pentagon was looking for a suitable propulsion system. U.S. manufacturer General Electric (GE) came up with an engine design featuring a larger fan than usual. The result was the TF39, the world’s first high-bypass turbofan engine. The advantage of this innovative technology is that the engines burn far less fuel—a factor that duly impressed the people in charge and won GE the contract for the Galaxy engines. The CF6 turned into a genuine success story for GE, with the commercial engine variant for the Douglas DC-10 marking the U.S. company’s entry into the commercial market in 1971. In that same year, GE signed a cooperation agreement with the still-fledgling company MTU in Munich covering the production of CF6-50 components for the Airbus A300. As a risk-and-revenue-sharing partner, the German engine manufacturer took on responsibility for sophisticated technical components of the two-stage cooled high-pressure turbine. In the 1980s, the CF6 gradually became the most popular engine for medium- and long-haul wide-body aircraft such as the Boeing 747 and 767, the Airbus models A300, A310 and A330 and the McDonnell Douglas MD-11. The CF6 family continued to grow, eventually comprising the versions CF6-50, CF6-80A, CF6-80C2 and CF6-80E1. Since entering into service in 1971, these engines have completed more flight hours than any other high-thrust commercial engine.
Maintenance, repair and overhaul of CF6 engines.
Having had such a positive experience with the successful collaboration on the CF6-50, GE was keen to get MTU on board once again for the CF6-80. In this follow-on project, the German company additionally participated in the engine post-design engineering phase, as well as in materials testing, vibration testing of critical assemblies and the manufacture of engine components for prototype engines and test facilities. The enhanced CF6-80C2 came into service in 1985, scoring particularly high thanks to the new standards it set for efficiency and reliability. The contract for collaboration on the Super Galaxy engine was inked in May 2003, with MTU taking on responsibility for a 9.1 percent share of the program.
“Participating in a foreign military engine project is a sign of the high regard in which our company is held,” comments Hiereth, “and it represents a huge advantage when it comes to future contracts. That’s because there are essentially three key things that determine a manufacturer’s position in the market: prominence, reliability, and quality. All of which MTU can rightly claim to offer.
