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
Lockheed C-5M Super Galaxy
McDonnell Douglas DC-10
McDonnell Douglas MD-11
Developed from General Electric TF39
Developed into General Electric LM6000

The General Electric CF6 is a family of high-bypass turbofan engines produced by GE Aviation. Based on the TF39, the first high-power high-bypass jet engine, the CF6 powers a wide variety of civilian airliners. The basic engine core also powers the LM2500, LM5000, and LM6000 marine and power generation turboshafts.

GE intends to replace the CF6 family with the GEnx.

Development[edit]

A CF6 turbofan installed on a testbed

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 the McDonnell Douglas DC-10. Lockheed eventually selected the Rolls-Royce RB211, but Douglas stuck with the CF6 and the DC-10 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, A310 and A330, Boeing 767, and McDonnell Douglas MD-11.

The high bypass of the CF6 represented a historic breakthrough in fuel efficiency.[1]

Variants[edit]

CF6-6[edit]

An FAA cutaway diagram of the CF6-6 engine

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).

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.[2]

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.

The engine is designated the General Electric F103 in United States Air Force service on KC-10 Extenders and Boeing E-4s.

CF6-80[edit]

CF6-80C2K1F Engine for the Kawasaki C-2

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]

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 LP compressor, and a 5th to the LP turbine.[3]

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, Kawasaki C-2(CF6-80C2K), as the F138-GE-100, the U.S. Air Force's C-5M Super Galaxy.

CF6-80E1[edit]

The 68,000 to 72,000 lbf (300 to 320 kN) variant competes with the Rolls-Royce Trent 700 and the Pratt & Whitney PW4000 to power the Airbus A330.[4]

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.[5]

Accidents and incidents[edit]

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

In 2000, the National Transportation Safety Board (NTSB) warned that the high-pressure compressor could crack.[7]

Following a series of high-pressure turbine failures on 6 September 1997,[8] 7 June 2000[9] and 8 December 2002,[10] and resulting in 767s being written off on 22 September 2000,[11] and on 2 June 2006,[12] the Federal Aviation Administration issued an airworthiness directive mandating inspections for over 600 engines and 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.[13]

In May 2010, The NTSB warned that the low-pressure turbine rotor disks could fail.[14] Four uncontained failures of CF6-45/50 engines in the preceding two years prompted it to issue an "urgent" recommendation to increase inspections of the engines on U.S. aircraft : 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[15]

Applications[edit]

CF6 with cutouts at The National Air and Space Museum in Washington, D.C.
cutouts detail : compressor at right, combustor in center and turbine at left

Specifications[edit]

CF6 Specifications[16]
Variant CF6-6 CF6-50 CF6-80A CF6-80C2 CF6-80E1
Type Dual rotor, axial flow, high bypass ratio turbofan, annular combustor
Compressor Fan & 1LP + 16HP Fan & 3LP + 14HP Fan & 4LP + 14HP
Turbine 2HP + 5LP 2HP + 4LP 2HP + 5LP
Length 188 in (478 cm) 183 in (465 cm) 167 in (424 cm) 168 in (427 cm)
Diameter 105 in (267 cm)[17][18][19] 106 in (269 cm)[3] 114 in (290 cm)[3]
Takeoff thrust 41,500 lbf
185 kN
51,500–54,000 lbf
229–240 kN
48,000–50,000 lbf
210–220 kN
52,200–61,960 lbf
232.2–275.6 kN
65,800–69,800 lbf
293–310 kN
Pressure ratio 25–25.2 29.2–31.1 27.3–28.4 27.1–31.8 32.4–34.8
Bypass ratio 5.76–5.92[17] 4.24–4.4[18] 4.59–4.66[19] 5–5.31[3] 5–5.1[20]
Max. power TSFC 0.35 lb/lbf/h
9.9 g/kN/s[17]
0.368–0.385 lb/lbf/h
10.4–10.9 g/kN/s[18]
0.355–0.357 lb/lbf/h
10.1–10.1 g/kN/s[19]
0.307–0.344 lb/lbf/h
8.7–9.7 g/kN/s[3]
0.332–0.345 lb/lbf/h
9.4–9.8 g/kN/s[3]
Application[21] DC-10-10 B747, DC-10-15/30, A300 A310, B767 A300/310, B747, B767, MD-11 A330
TCDS CF6-6[22] CF6-50[22] CF6-80A[23] CF6-80C2[23] CF6-80E1[24]
Weight[a] 8,176 lb
3,709 kg
8,825–9,047 lb
4,003–4,104 kg
8,760–8,776 lb
3,973–3,981 kg
9,480–9,860 lb
4,300–4,470 kg
11,225 lb
5,092 kg
Max. LP RPM 3,810 4,102 4,016 3,854 3,835
Max. HP RPM 9,925 10,761 10,859 11,055 11,105
Thrust-to-weight ratio 5.08 5.84–5.97 5.48–5.7 5.51–6.28 5.86–6.22
  1. ^ Dry, includes basic engine accessories & optional equipment

See also[edit]

Related development
Comparable engines
Related lists

References[edit]

  1. ^ Stephen Trimble (3 Jul 2015). "Industry sees path to carbon-neutral aviation". Flight Global. 
  2. ^ "New engine proposed as GE drops CF6-32" (PDF). Flightglobal. January 31, 1981. Retrieved October 23, 2013. 
  3. ^ a b c d e f "CF6-80C2 Engine". GE Aviation. 
  4. ^ "CF6-80E: Past, present and future" (PDF). Engine Yearbook. 2006. 
  5. ^ "LM6000 & SPRINT Aeroderivative Gas Turbine Packages (36 - 64 MW)". GE Distributed Power. Retrieved 2014-06-28. 
  6. ^ "National Airlines Flight 27, McDonnell Douglas DC-10-10, N60NA". Lessons Learned. Federal Aviation Administration. 
  7. ^ "Safety Recommendation A-00-104" (PDF). National Transportation Safety Board. August 9, 2000. 
  8. ^ "Report on aircraft C-FTCA 6 September 1997 engine failure". Aviation Safety Network. 
  9. ^ "Report on aircraft PP-VNN 7 June 2000 engine failure". Aviation Safety Network. 
  10. ^ "Report on aircraft ZK-NBC 8 December 2002 engine failure". Aviation Safety Network. 
  11. ^ "Report on aircraft N654US 22 September 2000 engine failure". Aviation Safety Network. 
  12. ^ "Report on aircraft N330AA 2 June 2006 engine failure". Aviation Safety Network. 
  13. ^ "NTSB wants at-risk GE CF6 engines removed". Flight International. September 5, 2006. 
  14. ^ "Four Recent Uncontained Engine Failure Events Prompt NTSB to Issue Urgent Safety Recommendations to FAA". National Transportation Safety Board. May 27, 2010. 
  15. ^ Mike M. Ahlers (May 28, 2010). "Jet engine failures overseas prompt 'urgent' NTSB recommendation here". CNN. 
  16. ^ "The CF6 Engine". GE Aviation. 
  17. ^ a b c "Model CF6-6". GE Aviation. 
  18. ^ a b c "Model CF6-50". GE Aviation. 
  19. ^ a b c "Model CF6-80A". GE Aviation. 
  20. ^ "Model CF6-80A". GE Aviation. 
  21. ^ "Commercial Aircraft Engines > CF6". MTU. 
  22. ^ a b "Type Certificate Data Sheet E23EA" (PDF). FAA. June 10, 2013. 
  23. ^ a b "Type Certificate Data Sheet E13NE" (PDF). FAA. September 11, 2014. 
  24. ^ "Type Certificate Data Sheet E41NE" (PDF). FAA. June 10, 2013. 

External links[edit]