| CF6 | |
|---|---|
| CF6 turbofan at the KLM engine shop | |
| Type | Turbofan |
| Manufacturer | GE Aviation |
| First run | 1971 |
| Major applications | Airbus A300 Airbus A330 Boeing 747 Boeing 767 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. 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.
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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] The NTSB issued warnings regarding the cracking of the high pressure compressor in 2000 and failure of the low pressure turbine rotor disks in 2010.[2][3]
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 41,500 lb (185.05 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.[4] The failure of a CF6-6 was the primary cause of the Sioux City, Iowa USA crash of United Airlines Flight 232 in 1989 .
The CF6-50 series are high-bypass turbofan engines rated between 51,000 and 54,000 lb (227.41 to 240.79 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.
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 in May 2010.[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]
The CF6-80 series are high-bypass turbofan engines with a thrust range of 48,000 to 75,000 lb (214 to 334 kN). It is an advanced development of the earlier successful CF6-50 series engine. 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,[6] [7] [8] some which resulted in 767s being written off,[9] [10] [11] the FAA has 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.
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.
The CF6-80C2, which entered revenue service in October 1985, has a thrust rating of 52,500 to 63,500 lb (234 to 282 kN).
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.
The CF6-80C2 is currently certified on eleven widebody aircraft models including the Boeing 747-400 (all variants), and McDonnell Douglas MD-11. The CF6-80C2 is also certified for ETOPS-180 for the A300, A310, Boeing 767, and, as the F138-GE-100, the U.S. Air Force's C-5M Super Galaxy.
The CF6-80E1 is a derivative of the successful CF6 family applied to the Airbus A330, with thrust rating of 67,500 to 73,530 lb (300 to 305 kN).
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 CF6-32 was intended to be a stripped-down version of the CF6-6 for the Boeing 757. It never went into production.
Data from [13]
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