CFM International CFM56

From Wikipedia, the free encyclopedia

You have new messages (last change).

CFM56-3

CFM56, front view

CFM International CFM56 series engines is a family of high-bypass turbofan engines made by CFM International and has a thrust range from 18,500 to 34,000 lb_f (82 kN to 151 kN). CFM International is a 50-50 joint company of Snecma, France and GE-Aviation, U.S.A. Both companies are responsible for producing various components, with each having their own final assembly line. GE is responsible for the high pressure compressor, combustor and high pressure turbine, while Snecma is responsible for the fan, low pressure turbine, the gearbox and the exhaust.

The CFM56 is one of the most prolific engine types in the world because of its long history starting with the Boeing 737-300. The 737 family has solely relied on the CFM56 for more than 25 years, and still powers the newest variants, the 737-900ER and 737-700ER. The engine is also an option on Airbus A320 series (including the A318, A319, and A321.) It is also the sole powerplant of the A340-300.

In U.S. Air Force use, the CFM56 has the designation of General Electric F108.

1 Variants
2 Future
3 External Links

[edit] Variants

The CFM56 powers short-, medium- and long-range aircraft. Its core turbomachinery is based on General Electric's F101 engine, which was developed for the B-1B Lancer strategic bomber. It entered service in 1982 and there are now 13,000 CFM56 engines of all types in service.

[edit] CFM56-2 series

This is the earliest of the series with a thrust range of between 22,000 to 24,000 lb_f (98 kN to 108 kN). It first appeared in the re-engined Douglas DC-8 Super 70 in 1982. Its success led to it re-engining military variants of Boeing 707. F108 is the engine's U.S. military designation. Today, the U.S. Air Force is CFM's largest customer, with more than 450 re-engined aircraft in service, or 1,800 CFM56-2 engines. This does not include later CFM56 variants on USAF and U.S. Navy 737 airframes. The -2 comprises a single stage fan, with a three-stage IP compressor, driven by a four-stage LP turbine, supercharging a nine-stage HP compressor, driven by a single stage, high work, HP turbine. The combustor is annular. Leading particulars for the -2C are bypass ratio of 6.0 and an overall pressure ratio of 24.7. The 68.3in diameter fan has an airflow of 788lb/s. The engine develops 22-24000 lb_f of static thrust.

[edit] CFM56-3 series

The first derivative of the CFM56 series, the CFM56-3 is designed for Boeing 737-300/-400/-500 series aircraft and is available with thrust ranging from 18,500 to 23,500 lb_f (82 kN to 105 kN). A cropped fan derivative of the -2, the engine has 60in diameter fan and retains the original engine layout.

The main problem with this series was the size of the engine for ground clearance, this was overcome by mounting the accessories on the lower sides to flatten the nacelle bottom and intake lip, giving a distinctive feature of the Boeing 737 with CFM56 engines. The engines were moved forward and raised, level with the upper surface of the wing and tilted 5 degrees up which not only helped the ground clearance but also directed the exhaust downwards which reduced the effects of pylon overheating and gave some vectored thrust to assist take-off performance. It was first certified by the FAA in January 1984.

It is the most numerous turbofan variant in aviation history with 3,975 engines produced for the 737-300/-400/-500. It is very reliable and has a high resale value, however the entire 737-400 fleet was grounded in 1989 owing to metal fatigue issues resulting in compressor failure. One such event would lead to the Kegworth air disaster.

Leading particulars for the -3B1 are bypass ratio 5.0, overall pressure ratio 27.5, airflow 655lb/s, static thrust 20000 lb_f.

[edit] CFM56-5 series

The CFM56-5 series is designed for the Airbus aircraft. It has a very wide thrust rating of between 22,000 to 34,000 lb_f (98 kN to 151 kN). It differs from its Boeing fitted cousins by features such as FADEC, advanced internal design giving improved performance over the CFM56-3 whilst maintaining the CFM56-3 reliability. It has 3 distinct sub-variants, the CFM56-5A, CFM56-5B and CFM56-5C. Both the CFM56-5A and CFM56-5B are ETOPS rated. The CFM56-5C is not due to its application in the 4-engined Airbus A340. The Airbus designator for any aircraft equipped with CFM engines is "1"; eg. A320-211 or A340-312.

[edit] CFM56-5A series

CFM56-5A series is designed to power the short-to-medium range Airbus A320 series, with thrusts between 22,000 to 26,500 lb_f (98 kN to 118 kN). This is the initial CFM56-5 series. Its design is derived from the CFM56-2 and CFM56-3 families. Mechanical arrangement and fan diameter as -2C.

Leading particulars for the 5/A1 are: bypass ratio 6.0, overall pressure ratio 31.2, airflow 852lb/s, static thrust 25000 lb_f.

[edit] CFM56-5B series

CFM56-5As power all of easyJet's A319s

An improvement of the CFM56-5A series, it was originally designed to power the A321. Today, it powers every model in the A320 family (A318/A319/A320/A321), and has superseded the CFM56-5A series. Among the change over the CFM56-5A is the double annular combustor technology which reduces oxides of nitrogen emission by as much as 45 percent. It is also the most numerous engine supplied to Airbus. The thrust range is between 22,000 to 33,000 lb_f (98 kN to 147 kN).

Mechanical arrangement and fan diameter as -5A, but with a 4th stage added to the IP compressor.

Leading particulars for the 5/B1 are: bypass ratio 5.5, overall pressure ratio 35.4, airflow 943lb/s, net thrust 30000lbf.

[edit] CFM56-5C series

With thrust rating of between 31,200 to 34,000 lb_f (139 kN to 151 kN), CFM56-5C series is the most powerful of the CFM56 family. It powers Airbus' long-range A340-200 and A340-300 airliners, and entered service in 1993. A fifth stage was added to the LP turbine.

For the A340, CFM International supplies the CFM56-5C series as a total propulsion system: engine, nacelle, and exhaust systems as opposed to just bare engines of the other variants.

It features exhaust design featuring mixer and an integrated nozzle for good efficiency (this design is also found in IAE V2500 series and on some Rolls-Royce RB211 series) and it also features the unique 'petal' thrust reversers rather than the conventional cascade design. This is due to the A340 requirements of maximum range and efficiency.

Leading particulars for the -5/C2 are: bypass ratio 6.6, overall pressure ratio 37.4, airflow 1027lb/s, net thrust 31200lbf.

[edit] CFM56-7 series

CFM56-5 installation on an A340

The image above is believed to be a replaceable fair use image. It will be deleted on 2007-04-06 if not determined to be irreplaceable. If you believe this image is not replaceable, follow the instructions on the image page to dispute this assertion.

The CFM56-7 powers the Next-Generation 737(Boeing 737-600/-700/-800/-900). The CFM56-7 is rated with takeoff thrust from 18,500 to 27,300 lb_f (82 kN to 121 kN).

It has higher thrusts, improved efficiency, and lower maintenance costs than its predecessor, the CFM56-3 series. It incorporates many features from the CFM56-5 series such as FADEC, double annular combustor and improved internal design. Mechanical arrangement is as in -3 series, but the fan diameter is increased to 61.0in.

The CFM56-7-powered 737 is granted 180-minute Extended-Range, Twin-Engine Operations (ETOPS) approval by the U.S. Federal Aviation Administration. It also powers the military versions of the Next-Generation 737, the C-40 Clipper, the P-8 Poseidon, and Project Wedgetail.

Leading particulars for the -7/B18 are: bypass ratio 5.5, overall pressure ratio 32.7, airflow 677lb/s, net thrust 19500lbf.

The CFM56-5B/5C/7 use essentially the same HP core. HP parts are dimensionally identical among the 5B/5C/7 although may or may not have different part numbers (source is ESM - Engine Shop Manual). Double annular combustor (DAC) is minority; most engines are SAC.

[edit] Future

CFM International is currently studying a new engine project, currently known as the LEAP56[1]. It is intended to be a successor to the CFM56-5B and CFM56-7. Currently proposed for the LEAP56 is a greater use of composite materials, as well as 10-15% lower fuel consumption. The proposed LEAP56 is considered by some to be one of the possible engines offered on the Boeing 737RS and Airbus NSR. CFM's main rival, International Aero Engines, has not yet made any proposals for a next generation engine, however, IAE members Rolls-Royce and Pratt & Whitney are currently studying their own designs for potential engine offerings on the 737RS/NSR.