General Electric CF6

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CF6
Turbofan640.jpg
CF6 turbofan at the KLM engine shop
Type Turbofan
Manufacturer GE Aviation
First run 1971
Major applications Airbus A300
Airbus A310
Airbus A330
Boeing 747
Boeing 767
McDonnell Douglas DC-10
McDonnell Douglas MD-11
Lockheed C-5M Super Galaxy
Developed from General Electric TF39
Developed into General Electric LM6000
CFM International CFM56

The General Electric CF6 is a family of high-bypass turbofan engines produced by GE Aviation. 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 intends to replace the CF6 family with the GEnx.

Development[edit]

After developing the TF39 for the C-5 Galaxy in the late 1960s, GE offered a more powerful variant for civilian use, 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. The L-1011 eventually selected the Rolls-Royce RB211, but 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]

In 2000, the NTSB issued warnings about cracking of the high-pressure compressor.[2] In 2010, it issued warnings about failure of the low-pressure turbine rotor disks.[3]

Variants[edit]

CF6-6[edit]

CF6 high-bypass turbofan

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

This initial version of the CF6 has a single-stage fan with one core booster stage, driven by a 5-stage LP (low pressure) turbine, turbocharging 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 1,300 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 41,500 lb (185.05 kN).

In 1973, a CF6-6 fan assembly disintegrated, resulted in the loss of cabin pressurization of National Airlines Flight 27 over New Mexico, USA.[4] In 1989, a CF6-6 failed, causing United Airlines Flight 232 to crash in Sioux City, Iowa.

CF6-50[edit]

The CF6-50 series are high-bypass turbofan engines rated between 51,000 and 54,000 lb (227.41 to 240.79 kN, or '25 tons') 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.

Not long after the -6 entered service, an increase in thrust and therefore core power was required. Unable to increase (HP) turbine rotor inlet temperature, General Electric chose the expensive path of reconfiguring the CF6 core to increase its basic size. They removed two stages from the rear of the HP compressor, leaving an empty air passage where the blades and vanes had once been. Two 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 1,450 lb/s (660 kg/s), yielding a static thrust of 51,000 lbf (227 kN). The increase in core size and overall pressure ratio raised the core flow, decreasing the 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 became 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.

In May 2010, four uncontained failures of CF6-45/50 engines in the preceding two years prompted the U.S. National Transportation Safety Board to issue an "urgent" recommendation to increase inspections of the engines on U.S. aircraft.[5] None of the four incidents of rotor disk imbalance and subsequent failure resulted in an accident, but parts of the engine did penetrate the engine housing in each case.[5]

CF6-80[edit]

Air Canada Boeing 767-300ER with CF6-80C2B6F engines

The CF6-80 series are high-bypass turbofan engines with a thrust range of 48,000 to 75,000 lb (214 to 334 kN). 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.[citation needed]

Following a series of high-pressure turbine failures,[6] [7] [8] some of which resulted in 767s being written off,[9] [10] [11] the FAA issued an airworthiness directive mandating inspections for over 600 engines. The NTSB believed that this number should be increased to include all -80 series engines with more than 3000 cycles since new or since last inspection.[12]

The -80 series is divided into three distinct models.

CF6-80A[edit]

The CF6-80A, which has a thrust rating of 48,000 to 50,000 lb (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[edit]

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 lb (263 kN). An extra stage is added to the HP compressor, and a 5th to the LP turbine.[13]

The CF6-80C2 is currently certified on eleven widebody aircraft models including the Boeing 747-400, and McDonnell Douglas MD-11. The CF6-80C2 is also certified for ETOPS-180 for the Airbus A300, Airbus A310, Boeing 767, and, as the F138-GE-100, the U.S. Air Force's C-5M Super Galaxy.

CF6-80E1[edit]

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 lb (300 to 320 kN).[14]

Other variants[edit]

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. The LM6000 gas turbine family provides power in the 40 to 56 MW range for utility, industrial, and oil & gas applications.[15]

Undeveloped variants[edit]

The General Electric CF6-32 was to be a lower thrust derivative of the CF6-6 for the Boeing 757. In 1981, General Electric formally abandoned development of the engine, leaving the Boeing 757 engine market to Pratt & Whitney and Rolls-Royce.[16]

Applications[edit]

Specifications (CF6-50)[edit]

An FAA cutaway diagram of the CF6-6 engine

Data from General Electric.[17]

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
  • Combustors: annular
  • Turbine: 2 stage high pressure, 4 stage low pressure turbine

Performance

See also[edit]

Related development
Comparable engines
Related lists

References[edit]

  1. ^ General Electric - Model TF39
  2. ^ "Safety Recommendation A-00-104" (PDF). National Transportation Safety Board. August 9, 2000. 
  3. ^ "FOUR RECENT UNCONTAINED ENGINE FAILURE EVENTS PROMPT NTSB TO ISSUE URGENT SAFETY RECOMMENDATIONS TO FAA". National Transportation Safety Board. May 27, 2010. 
  4. ^ Applying Lessons Learned - National Airlines Flight 27 Federal Aviation Administration
  5. ^ a b Ahlers, Mike M. (May 28, 2010), Jet engine failures overseas prompt 'urgent' NTSB recommendation here, CNN, retrieved 2010-05-28 
  6. ^ Report on aircraft C-FTCA 6 September 1997 engine failure Aviation Safety Network
  7. ^ Report on aircraft PP-VNN 7 June 2000 engine failure Aviation Safety Network
  8. ^ Report on aircraft ZK-NBC 8 December 2002 engine failure Aviation Safety Network
  9. ^ Report on aircraft N654US 22 September 2000 engine failure Aviation Safety Network
  10. ^ Report on aircraft N330AA 2 June 2006 engine failure Aviation Safety Network
  11. ^ N330AA photos airliners.net
  12. ^ NTSB wants at-risk GE CF6 engines removed Flight International, September 5, 2006
  13. ^ CF6-80C2 Engine | Commercial Aviation | Jet Engines | GE Aviation. http://www.geaviation.com/engines/commercial/cf6/cf6-80c2.html. Accessed May 12, 2013.
  14. ^ CF6-80E1 Engine | Commercial Aviation | Jet Engines | GE Aviation. http://www.geaviation.com/engines/commercial/cf6/cf6-80e1.html. Accessed May 12, 2013.
  15. ^ "LM6000 & SPRINT Aeroderivative Gas Turbine Packages (36 - 64 MW)". GE Distributed Power. Retrieved 2014-06-28. 
  16. ^ "New engine proposed as GE drops CF6-32". Flightglobal. January 31, 1981. Retrieved October 23, 2013. 
  17. ^ GE CF6-50. http://geae.com/engines/commercial/cf6/cf6-50.html. Accessed Oct 3 2009.

External links[edit]