CFM International CFM56

CFM56
	CFM56-5
Type	Turbofan
National origin	France and United States
Manufacturer	CFM International
First run	1970s
Major applications	Airbus A320 family ; Boeing 737 Classic ; Boeing 737 Next Generation ; KC-135R Stratotanker
Number built	13,000+
Developed from	General Electric F101
Developed into	CFM International LEAP-X

CFM International CFM56 series engines (US military designation F108) are a family of high-bypass turbofan engines made by CFM International with 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 engines are assembled by GE in Evendale, Ohio, USA and by Snecma in Villaroche, France.

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 the CFM56 still powers the newest variants, the 737-900ER and 737-700ER. The engine is also an option on Airbus A320 family. It is also the sole powerplant of the A340-200 & -300. The F108 replaced the Pratt & Whitney JT3D engines on the KC-135 Stratotanker in the 1980s to create the KC-135R, achieving a 27% fuel savings.^[1]

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.^[2]

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 CFM56-2 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 CFM56-2C 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 22,000-24,000 lb_f of static thrust.

CFM56-3 series

The first derivative of the CFM56 series, the CFM56-3 was designed for Boeing 737-300/-400/-500 series aircraft, with static thrust ratings from 18,500 to 23,500 lb_f (82 kN to 105 kN). A cropped fan derivative of the -2, the -3 engine has a smaller 60in fan diameter and lower bypass ratio, but retains the original basic engine layout.

A significant challenge for this series was the size of the wing-mounted engine for ground clearance. This was partially overcome by mounting the accessories at the lower corners, and flattening the nacelle bottom and intake lip, thus giving a distinctive appearance of the Boeing 737 with CFM56 engines. The engines were also moved forward and raised, with the top nacelle surface essentially level with the upper surface of the wing, and tilted 5 degrees up. This not only helped increase the ground clearance but also directed the exhaust downwards which reduced the effects of pylon overheating and gave some vectored-thrust effect, assisting take-off performance.^{[citation needed]}

It was first certified by the US Federal Aviation Administration in January 1984. It became 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.

Following the Kegworth air disaster of 1989, due to metal fatigue causing compressor failure in the engine, the entire 737-400 fleet was temporarily grounded.

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

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 Airbus designator for any aircraft equipped with CFM engines is "1"; eg. A320-211 or A340-312.

CFM56-5A series

CFM56-5A series is designed to power the short-to-medium range Airbus A320 family, 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.

CFM56-5B series

File:DSCF6247a.jpg

CFM56-5Bs 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.

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 -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.

Its exhaust design features a mixer with integrated nozzle for better efficiency (this design is also found in IAE V2500 series and on some RB211 series) and it also features a 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.

CFM56-7 series

The CFM56-7 powers the Boeing 737 Next Generation series (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 Boeing 737 AEW&C.

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.

Applications

Specifications

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References

External links

Official website

[1] Boeing: Integrated Defense Systems - Logistics Support Systems - KC-135 Stratotanker - KC-135 Stratotanker Home

[2] Case study

[1]

[2]

v t e GE Aircraft Engines/GE Aviation/GE Aerospace aircraft engines
Turbojets	CJ610 CJ805 GE1 GE4/J5 I-A J31 J33 J35 J47 J73 J79 J85 J87 YJ93 J97 YJ101
Turbofans	Affinity CF6 CF34 CF700 CFE738† CFM56† CJ805-23 GE90 GE9X GEnx GP7000† HF120† LEAP† Passport F101 F108† F110 F118 YF120 F136† F404/F412 F414 RM12† RM16 TF34 TF39 XA100 XA102
Turboprops and turboshafts	Catalyst CT7 CT58 CT64 GE27 GE38 H-Series T31 T58 T64 T407 T408 T700 T901
Aeroderivative gas turbine engines	LM500 LM1500 LM1600 LM2500 LM6000 LM9000 LMS100
Propfans	GE36 RISE†
† Joint development aeroengines

v t e United States military gas turbine aircraft engine designation system
Turbojets	J30 J31 J32 J33 J34 J35 J36 J37 XJ38 J39 J40 XJ41 J42 J43 J44 J45 J46 J47 J48 XJ49 J51 J52 J53 J54 J55 J56 J57 J58 J59 J60 J61 J63 J65 J67 J69 J71 J73 J75 J79 J81 J83 J85 J87 J89 J91 YJ93 J95 J97 J99 J100 YJ101 J102 J400 J401 J402 J403 J700
Turboprops/ Turboshafts	T30 T31 T33 T34 T35 T36 T37 T38 T39 T40 T41 T42 T43 T44 T45 T46 T47 T48 T49 T50 T51 T52 T53 T54 T55 T56 (variants) T57 T58 T60 T61 T62 T63 T64 T65 T66 T67 T68 T69 T70 T71 T72 T73 T74 T76 T78 T80 T100 T101 T400 T405 T406 T407 T408 T700 T701 T702 T703 T706 T708 LHTEC T800 APW T800 T900 T901
Turbofans	TF30 TF31 TF32 TF33 TF34 TF35 TF37 TF39 TF41 F100 F101 F102 F103 F104 F105 F106 F107 F108 F109 F110 F112 F113 F117 F118 F119 YF120 F121 F122 F124 F125 F126 F127 F128 F129 F130 F135 F136 F137 F138 F400 F401 F402 F404 F405 F408 F412 F414 F415
Adaptive cycle engines	XA100 XA101 XA102 XA103

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