General Electric CF6: Wikis

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CF6
CF6 turbofan at the KLM engine shop
Type Turbofan
Manufacturer GE Aviation
First run 1971
Major applications Airbus A300
Boeing 747
Boeing 767
McDonnell Douglas DC-10
Developed from General Electric TF39
Developed into General Electric LM6000

The General Electric CF6 is a family of high-bypass turbofan engines. A development of the first high-power high-bypass jet engine available, the TF39, the CF6 powers a wide variety of civilian airliners. The basic engine core formed the basis for the LM2500, LM5000, and LM6000 marine and power generation turboshaft. GE Aviation intends to replace the CF6 family with the GEnx.

Contents

Development

CF6 high-bypass turbofan

After the successful development in the late 1960s of the TF39 for the C-5 Galaxy, GE offered a more powerful development for civilian use as the CF6, and quickly found interest in two designs being offered for a recent Eastern Airlines contract, the Lockheed L-1011 and McDonnell Douglas DC-10. Although the L-1011 would eventually select the Rolls-Royce RB211, the DC-10 stuck with the CF6, and entered service in 1971. It was also selected for versions of the Boeing 747. Since then, the CF6 has powered versions of the Airbus A300, 310 and 330, Boeing 767, and McDonnell Douglas MD-11.[1]

Variants

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CF6-6

The CF6-6 was a development of the military TF39. It was first utilized on the McDonnell Douglas DC-10-10.

This initial version of the CF6 comprises a single stage fan, with one core booster stage, driven by a 5-stage LP (low pressure) turbine, supercharging a 16-stage HP (high pressure) axial compressor driven by a 2-stage HP turbine; the combustor is annular; separate exhaust nozzles are used for the fan and core airflows. The 86.4 in (2.19 m) diameter fan generates an airflow of 1300 lb/s (590 kg/s), resulting in a relatively high bypass ratio of 5.72. The overall pressure ratio of the compression system is 24.3. At maximum take-off power, the engine develops a static thrust of 40,000 lbf (178 kN).

A complete disintegration of a CF6-6 fan assembly resulted in the loss of cabin pressurization of National Airlines Flight 27 over New Mexico, USA in 1973.[2] The failure of a CF6-6 was the primary cause of the Sioux City, Iowa USA crash of United Airlines Flight 232 in 1989 .

CF6-50

The CF6-50 series are high-bypass turbofan engines rated between 46,000 and 54,000 lbf (205 to 240 kN) of thrust. The CF6-50 was developed into the LM5000 industrial turboshaft engines. It was launched in 1969 to power the long range McDonnell Douglas DC-10-30, and was derived from the earlier CF6-6.

Because a significant increase in thrust and therefore core power was required not long after the -6 had entered service, General Electric could not increase (HP) turbine rotor inlet temperature significantly, so they took the very expensive decision to reconfigure the CF6 core to increase its basic size. They achieved this by removing two stages from the rear of the HP compressor (even leaving an empty air passage, where the blades and vanes had once been located). Two extra booster stages were added to the LP (low pressure) compressor, which increased the overall pressure ratio to 29.3. Although the 86.4 in (2.19 m) diameter fan was retained, the airflow was raised to 1450 lb/s (660 kg/s), yielding a static thrust of 51,000 lbf (227 kN). The increase in core size and overall pressure ratio, significantly raised the core flow, resulting in a decrease in bypass ratio to 4.26.

In late 1969, the CF6-50 was selected to power the then new Airbus A300. Air France became the launch customer for the A300 by ordering six aircraft in 1971. In 1975, KLM was the first airline to order the Boeing 747 powered by the CF6-50. This led further developments to the CF6 family such as the CF6-80. The CF6-50 also powered the Boeing YC-14 USAF AMST transport prototype.

The basic CF6-50 engine was also offered with a 10% thrust derate for the 747SR, a short-range high-cycle version used by All Nippon Airways for domestic Japanese operations. This engine is termed the CF6-45.

CF6-80

The CF6-80 series are high-bypass turbofan engines with a thrust range of 48,000 to 75,000 lbf (214 to 334 kN). It is an advanced development of the earlier successful CF6-50 series engine, but despite superficial resemblance, it is a completely new engine with no interchangeable parts. Although the HP compressor still has 14 stages, GE did take the opportunity to tidy-up the design, by removing the empty air passage at compressor exit. A shorter combustor further reduced the overall length, permitting the removal of one bearing sump (due to a shorter and stiffer fan drive shaft).

Following a series of high-pressure turbine failures,[3] [4] [5] some which resulted in 767s being written off,[6] [7] [8] the FAA has issued an airworthiness directive mandating inspections for over 600 engines. The NTSB feels this number should be increased to include all -80 series engines with more than 3000 cycles since new or since last inspection. [9]

The -80 series is divided into three distinct models.

CF6-80A

The CF6-80A, which has a thrust rating of 48,000 to 50,000 lbf (214 to 222 kN), powered two twinjets, the Boeing 767 and Airbus A310. The GE-powered 767 entered airline service in 1982, and the GE powered A310 in early 1983. It is rated for ETOPS operations.

For the CF6-80A/A1, the fan diameter remains at 86.4 in (2.19 m), with an airflow of 1435 lb/s (651 kg/s). Overall pressure ratio is 28.0, with a bypass ratio of 4.66. Static thrust is 48,000 lbf (214 kN). The basic mechanical configuration is the same as the -50 series.

CF6-80C2
A Delta Air Lines Boeing 767-400ER with CF6-80C2 engines

The CF6-80C2, which entered revenue service in October 1985, has a thrust rating of 52,500 to 63,500 lbf (234 to 282 kN). It has a reputation of good new engine fuel economy in its thrust class, but unfortunately degrades quickly over time. The CF6-80C2 is certified with 16 different thrust ratings. This versatile engine has the most widespread use of any large turbofan engine.[citation needed]

For the CF6-80C2-A1, the fan diameter is increased to 93 in (2.36 m), with an airflow of 1750 lb/s (790 kg/s). Overall pressure ratio is 30.4, with a bypass ratio of 5.15. Static thrust is 59,000 lbf (263 kN). An extra stage is added to the HP compressor, and a 5th to the LP turbine.

The CF6-80C2 is currently certified on eleven wide-body aircraft models including the Boeing 747 and McDonnell Douglas MD-11. The CF6-80C2 is also certified for ETOPS-180 for the A300, A310, Boeing 767, and, as the F108-GE-100, the U.S. Air Force's C-5M Super Galaxy.

CF6-80E1

The CF6-80E1 is a derivative of the successful CF6 family applied to the Airbus A330, with thrust rating of 67,500 to 72,000 lbf (300 to 334 kN). For the CF6-80E1A2, the fan diameter is increased to 96 in (2.44 m), with an airflow of 1925 lb/s (875 kg/s). Overall pressure ratio is 32.6, with a bypass ratio of 5.3.[citation needed]

The CF6-80E1A3 was a stretch too far for the family with severe deterioration in service resulting in a rating (CF6-80E1A4B) that allows temporary use of 72,000lb when temperature margins allow (citation needed). An upgrade to the CF6 is planned to address this shortcoming.

Other variants

The industrial and marine development of the CF6-80C2, the LM6000 Series, has found wide use including fast ferry and high speed cargo ship applications, as well as in power generation. Unlike the LM2500 and LM5000, it is capable of cold (compressor) end drive allowing for an axial exhaust which aids power output and efficiency. The LM6000 actually uses the LP compressor section from the CF6-50.

CF6-32

The CF6-32 was intended to be a stripped-down version of the CF6-6 for the Boeing 757. It was never launched due to lack of interest from airlines following the success of the PW2000 and RB211-535 engines.

Applications

CF6-6
CF6-50
CF6-80

Specifications (CF6-50)

An FAA cutaway diagram of the CF6-6 engine

Data from [10]

General characteristics

  • Type: Turbofan
  • Length: 183 in (4.65 m)
  • Diameter: 105 in (2.67 m)
  • Dry weight: 8,966 - 9,047 lb (4067 kg - 4104 kg)

Components

  • Compressor: 1 stage fan, 3 stage low pressure, 14 stage high pressure axial compressor
  • Turbine: 2 stage high pressure, 4 stage low pressure turbine

Performance

See also

Comparable engines

Related lists

References

External links


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