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The CFM International CFM56 (U.S. military designation F108) series is a Franco-American family of high-bypass turbofan aircraft engines made by CFM International (CFMI), with a thrust range of 18,500 to 34,000 lbf (82 to 150 kN). CFMI is a 50–50 joint-owned company of Safran Aircraft Engines (formerly known as Snecma) of France, and GE Aviation (GE) of the United States. Both companies are responsible for producing components and each has its own final assembly line. GE produces the high-pressure compressor, combustor, and high-pressure turbine, Safran manufactures the fan, gearbox, exhaust and the low-pressure turbine, and some components are made by Avio of Italy and Honeywell from the US. The engines are assembled by GE in Evendale, Ohio, and by Safran in Villaroche, France. The completed engines are marketed by CFMI. Despite initial export restrictions, it is the most used turbofan aircraft engine in the world, in four major variants.
The CFM56 first ran in 1974.[2] By April 1979, the joint venture had not received a single order in five years and was two weeks away from being dissolved.[3] The program was saved when Delta Air Lines, United Airlines, and Flying Tigers chose the CFM56 to re-engine their DC-8s and shortly thereafter it was chosen to re-engine the Boeing KC-135 Stratotanker fleet of the U.S. Air Force.[3] The first engines entered service in 1982.[4] Several fan blade failure incidents were experienced during the CFM56's early service, including one failure that was a cause of the Kegworth air disaster, and some engine variants experienced problems caused by flight through rain and hail. Both of these issues were resolved with engine modifications.Research into the next generation of commercial jet engines, high-bypass ratio turbofans in the "10-ton" (20,000 lbf; 89 kN) thrust class, began in the late 1960s. Snecma (now Safran), who had mostly built military engines previously, was the first company to seek entrance into the market by searching for a partner with commercial experience to design and build an engine in this class. They considered Pratt & Whitney, Rolls-Royce, and GE Aviation as potential partners, and after two company executives, Gerhard Neumann from GE and René Ravaud from Snecma, introduced themselves at the 1971 Paris Air Show a decision was made. The two companies saw mutual benefit in the collaboration and met several more times, fleshing out the basics of the joint project.[5]
At the time, Pratt & Whitney dominated the commercial market. GE needed an engine in this market class, and Snecma had previous experience of working with them, collaborating on the production of the CF6-50 turbofan for the Airbus A300.[2] Pratt & Whitney was considering upgrading their JT8D to compete in the same class as the CFM56 as a sole venture, while Rolls-Royce dealt with financial issues that precluded them from starting new projects; this situation caused GE to gain the title of best partner for the program.[5]
A major reason for GE's interest in the collaboration, rather than building a 10-ton engine on their own, was that the Snecma project was the only source of development funds for an engine in this class at this particular time. GE was initially considering only contributing technology from its CF6 engine rather than its much more advanced F101 engine, developed for the B-1 Lancer supersonic bomber. The company was faced with a dilemma when the United States Air Force (USAF) announced its Advanced Medium STOL Transport (AMST) project in 1972 which included funding for the development of a 10-ton engine – either to build a "limited" technology 10-ton engine with Snecma, or a similar engine with "advanced" technology on their own. Concerned that the company would be left with only the "limited" engine in its portfolio if it did not win the Air Force contract (for which it was competing with Pratt & Whitney and a General Motors division with its "advanced" engine), GE decided to apply for an export license for the F101 core technology.[6]
Export issues
GE applied for the export license in 1972 as their primary contribution to the 10-ton engine project. The United States Department of State's Office of Munitions Control recommended the rejection of the application on national security grounds; specifically because the core technology was an aspect of a strategic national defense system (B-1 bomber), it was built with Department of Defense funding, and that exporting the technology to France would limit the number of American workers on the project.[7] The official decision was made in a National Security Decision Memorandum signed by the National Security Advisor Henry Kissinger on 19 September 1972.[8]
While national security concerns were cited as the grounds for rejection, politics played an important role as well. The project, and the export issue associated with it, was considered so important that French President Georges Pompidou appealed directly to U.S. President Richard Nixon in 1971 to approve the deal, and Henry Kissinger brought the issue up with President Pompidou in a 1972 meeting. GE reportedly argued at the highest levels that having half of the market was better than having none of it, which they believed would happen if Snecma pursued the engine on their own without GE's contribution. Nixon administration officials feared that this project could be the beginning of the end of American aerospace leadership.[9]
There was also speculation that the rejection may have been, in part, retaliation for French involvement in convincing the Swiss not to purchase American-made LTV A-7 Corsair II aircraft that had been competing against a French design,[9] the Dassault Milan. In the end, the Swiss did not purchase either aircraft, opting for the Northrop F-5E Tiger II instead.
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