CFM International CFM56
The CFM International CFM56 series is a Franco-American family of high-bypass turbofan aircraft engines made by CFM International, with a thrust range of. CFMI is a 50–50 joint-owned company of Safran Aircraft Engines of France, and GE Aerospace of the United States. 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. Both companies have their own final assembly line, GE in Evendale, Ohio, and Safran in Villaroche, France. The engine initially had extremely slow sales but has gone on to become the most used turbofan aircraft engine in the world.
The CFM56 first ran in 1974. By April 1979, the joint venture had not received a single order in five years and was two weeks away from being dissolved. The program was saved when Delta Air Lines, United Airlines, and Flying Tigers chose the CFM56 to re-engine their Douglas DC-8 aircraft as part of the Super 70 program. The first engines entered service in 1982. The CFM56 was later selected to re-engine the Boeing 737. Boeing initially expected this re-engine program to sell only modestly, but in fact the CFM56's lower noise and lower fuel consumption led to strong sales.
In 1987, the IAE V2500 engine for the A320, which had beaten the CFM56 in early sales of the A320, ran into technical trouble, leading many customers to switch to the CFM56. However, the CFM56 was not without its own issues; several fan blade failure incidents were experienced during early service, including one failure that was a cause of the Kegworth air disaster, and some CFM56 variants experienced problems when flying through rain or hail. Both of these issues were resolved with engine modifications.
History
Origins
Research into the next generation of commercial jet engines, high-bypass ratio turbofans in the "10-ton" thrust class, began in the late 1960s. Snecma, 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.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. 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.
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 announced its Advanced Medium STOL Transport 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, GE decided to apply for an export license for the F101 core technology.
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, 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. The official decision was made in a National Security Decision Memorandum signed by the National Security Advisor Henry Kissinger on 19 September 1972.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.
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, the Dassault Milan. In the end, the Swiss did not purchase either aircraft, opting for the Northrop F-5E Tiger II instead.
1973 Nixon–Pompidou meeting
Despite the export license being rejected, both the French and GE continued to push the Nixon Administration for permission to export the F101 technology. Efforts continued throughout the months following the rejection, culminating in the engine becoming an agenda topic during the 1973 meeting of Presidents Nixon and Pompidou in Reykjavík. Discussions at this meeting resulted in an agreement that allowed the development of the CFM56 to proceed. Contemporary reports state that the agreement was based on assurances that the core of the engine, the part that GE was developing from the military F101, would be built in the U.S. and then transported to France in order to protect the sensitive technologies. The joint venture also agreed to pay the U.S. an $80 million royalty fee as repayment for the development money provided by the government for the F101 engine core. Documents declassified in 2007 revealed that a key aspect of the CFM56 export agreement was that the French government agreed not to seek tariffs against American aircraft being imported into Europe.CFM International
With the export issue settled, GE and Snecma finalized the agreement that formed CFM International, a 50–50 joint company that would be responsible for producing and marketing the 10-ton engine, the CFM56. The venture was officially founded in 1974. The "CF" in the engine name stands for GE's designation for commercial turbofan engines, while the "M56" is the name of Snecma's original engine proposal. The two primary roles for CFMI were to manage the program between GE and Snecma, and to market, sell and service the engine at a single point of contact for the customer. CFMI was made responsible for the day-to-day decision making for the project, while major decisions required the go-ahead from GE and Snecma management.The CFMI board of directors is currently split evenly between Snecma and GE. There are two vice presidents, one from each company, who support the President of CFMI. The president tends to be drawn from Snecma and sits at CFMI's headquarters near GE in Cincinnati, Ohio.
The work split between the two companies gave GE responsibility for the high-pressure compressor, the combustor, and the high-pressure turbine ; Snecma was responsible for the fan, the low-pressure compressor, and the low-pressure turbine. Snecma was also responsible for the initial airframe integration engineering, mostly involving the nacelle design, and was initially responsible for the gearbox, but shifted that work to GE when it became apparent that it would be more efficient for GE to assemble that component along with their other parts.
Development
Overview
Development work on the CFM56 began before CFMI was formally created. While work proceeded smoothly, the international arrangement led to unique working conditions. For example, both companies had assembly lines, some engines were assembled and tested in the U.S. and others in France. Engines assembled in France were subject to the initially strict export agreement, which meant that GE's core was built in the U.S., then shipped to the Snecma plant in France where it was placed in a locked room into which even the President of Snecma was not allowed. The Snecma components were brought into the room, GE employees mounted them to the core, and then the assembled engine was taken out to be finished.The first completed CFM56 engine first ran at GE plant in Evendale on 20 June 1974 with the second running in October 1974. The second engine was then shipped to France and first ran there on 13 December 1974. These first engines were considered "production hardware" as opposed to test examples and were designated as the CFM56-2, the first variant of the CFM56.
The engine flew for the first time in February 1977 when it replaced one of the four Pratt & Whitney JT8D engines on the McDonnell Douglas YC-15, an entrant in the Air Force's Advanced Medium STOL Transport competition. Soon after, the second CFM56 was mounted on a Sud Aviation Caravelle at the Snecma flight test center in France. This engine had a slightly different configuration with a long bypass duct and mixed exhaust flow, rather than a short bypass duct with unmixed exhaust flow. It was the first to include a "Thrust Management System".