1. Development

2. Design

3. Operational history
    Records 

4. Incidents
    Transfer gearbox failures 

5. Specifications

6. Derivatives
    GEnx  GP7000  GE9X  LM9000 

7. See also

8. References
    Notes 

9. External links

The General Electric GE90 is a family of high-bypass turbofan aircraft engines built by GE Aviation for the Boeing 777, with thrust ratings from {{convert|81000|to|115000|lbf|kN|abbr=on}}. It entered service with British Airways in November 1995. It is one of three options for the 777-200, -200ER, and -300 versions, and the exclusive engine of the -200LR, -300ER, and 777F. It is the world's largest and the most powerful jet engine.^[2] Its {{cvt|{{#expr:134-128}}|in|cm}} wider fan successor, the {{cvt|105000|lbf|kN}} GE9X, is expected to power the Boeing 777X from 2019.

Development

The GE90 was developed from the NASA 1970s Energy Efficient Engine. GE's GE36 UDF (propfan) was meant to replace the CFM International CFM56 high-bypass turbofan which was initially noncompetitive against the rival IAE V2500. However, when the V2500 ran into technical problems, sales of the CFM56 took off. GE was not interested in having the GE36 cannibalize the CFM56, and while "the UDF could be made reliable by earlier standards, turbofans were getting much, much better than that." However, GE integrated the UDF’s blade technology directly into the GE90.^[3]

The GE90 engine was launched in 1990.^[4] GE Aviation teamed with Snecma (France, 24%), IHI (Japan) and Avio (Italy) for the program.^[5]

Initially the GE90 was only one of three 777 options and GE Aviation then-CEO Brian H. Rowe would have paid for the development of putting it on an A330, but Airbus' strategy for long-haul was the four-engine A340, missing the market favouring twins.^[6]

Design

The GE90's 10-stage high-pressure compressor develops an industry record pressure ratio of 23:1 and is driven by a 2-stage, air-cooled, HP turbine. A 3-stage low-pressure compressor, situated directly behind the fan, supercharges the core. The fan/LPC is driven by a 6-stage low-pressure turbine.

The higher-thrust variants, GE90-110B1 and -115B, have a different architecture from the earlier GE90 versions, with one stage removed from the HP compressor and an extra stage added to the LP compressor. A net increase in core flow was achieved. General Electric performed a similar re-staging exercise when they upgraded the CF6 from the -6 to the higher-thrust -50. However, this thrust growth route is expensive, since all the downstream components (e.g. turbines) must be larger for flow capacity. The fan is an advanced, larger diameter unit made from composite materials and is the first production engine to feature swept rotor blades.^[3][11]

Its nacelle has a maximum diameter of {{cvt|166|in}}.^[7]

Operational history

As one of the three available engines for the new Boeing 777, the GE90 was an all-new $2 billion design meant to handle transoceanic routes, in contrast to the offerings from Pratt & Whitney and Rolls-Royce which were modifications of existing engines.^[3]

The first General Electric-powered Boeing 777 was delivered to British Airways on November 12, 1995.^[8] The aircraft, with two GE90-77Bs, entered service five days later. Initial service was affected by gearbox bearing wear concerns, which caused the airline to temporarily withdraw its 777 fleet from transatlantic service in 1997. British Airways' aircraft returned to full service later that year.^[9]

Problems with GE90 development and testing caused delays in Federal Aviation Administration certification. In addition the GE90's increased output was not yet put to use by airlines and it was also the heaviest engine of the three available choices, making it the least popular option while Rolls-Royce held the top spot. British Airways soon replaced the GE90 with Rolls-Royce engines on their 777s.^[3][11]

For Boeing's second-generation 777 long-range versions (later named 777-200LR, 777-300ER, and 777F), greater thrust was needed to meet the specifications. General Electric and Pratt & Whitney insisted on a winner-take-all contract due to the $500 million investment in engine modifications needed to meet the requirements. GE received sole engine supplier status for the higher-thrust engine variants for the 777-200LR, -300ER, and 777F.^[10][11]

The higher-output GE90-110B1 and -115B engines, in combination with the second-generation 777 variants -200LR and -300ER, has been a primary driver of the twinjet's sales past the rival A330/340 series.^[12] Using two engines produces a typical operating cost advantage of around 8–9% for the -300ER over the A340-600.^[13] The 777-300ER has also been seen as a 747-400 replacement amid rising fuel prices given its 20% fuel burn advantage.^[14]

Until passed by its derivative, the GE9X, the GE90 series held the title of the largest engines in aviation history. The fan diameter of the original series being {{convert|123|in|cm|abbr=on}}, and the largest variant GE90-115B has a fan diameter of {{convert|128|in|cm|abbr=on}}. As a result GE90 engines can only be air freighted in assembled form by outsize cargo aircraft such as the Antonov An-124, presenting unique problems if, due to emergency diversions, a 777 were stranded in a place without the proper spare parts. If the fan is removed from the core, then the engines may be shipped on a 747 Freighter.^[15]

The -94B for the -200ER is being retrofitted with some of the first FAA-approved 3D-printed components.^[16]

It has an in-flight shutdown rate (IFSD) of one per million engine flight-hours.^[2] It accumulated more than 8 million cycles and 50 million flight hours in 20 years.^[17]

Records

The GE90-115B is powerful enough to fully operate GE's Boeing 747 testbed on its own power, an attribute demonstrated during a flight test.^[18][19]

According to the Guinness Book of Records, at {{convert|127900|lbf|kN|abbr=on}}, the engine holds the record for the highest thrust (although rated at {{convert|115300|lbf|kN|abbr=on}}). This thrust record was accomplished inadvertently as part of a one-hour, triple-red-line engine stress test. To accommodate the increase in torsional stresses, a new steel alloy, GE1014 was created and then machined to extreme tolerances.^[20] The new record was set during testing of a GE90-115B development engine at GE Aviations' Peebles Test Operation, which is an outdoor test complex outside Peebles, Ohio. It eclipsed the engine's previous Guinness world record of {{convert|122965|lbf|kN|abbr=on}}.^[21]

In October 2003, a Boeing 777-300ER broke the ETOPS record by being able to fly five and a half hours (330 minutes) with one engine shut down.^[22] The aircraft, with GE90-115B engines, flew from Seattle to Taiwan as part of the ETOPS certification program.

On November 10, 2005, the GE90 entered the Guinness World Records for a second time. The GE90-110B1 powered a 777-200LR during the world's longest flight by a commercial airliner, though there were no fare-paying passengers on the flight, only journalists and invited guests. The 777-200LR flew {{convert|13422|mi|km|abbr=on}} in 22 hours, 42 minutes, flying from Hong Kong to London "the long way": over the Pacific, over the continental U.S., then over the Atlantic to London.^[23]

Incidents

On August 11, 2004 a GE90-85B powering a Boeing 777-200ER on British Airways flight 2024 suffered an engine failure on takeoff from George Bush Intercontinental Airport, Houston. The pilots noticed a noise and vibration on takeoff but continued the rotation. At 1500 ft AGL they noticed smoke and haze in cockpit and cabin crew advised cabin was filling with smoke. They returned to the airport for an immediate emergency landing.

Findings were a stage 2 turbine blade had separated at its shank damaging the trailing blades causing the vibration. The debris was contained in the engine casing.^[24]

On May 28, 2012, an Air Canada 777 taking off from Toronto en route to Japan suffered failure of a GE90-115B at {{convert|1500|ft|m}} and returned safely. Engine debris was found on the ground.^[25][26]

On September 8, 2015, a GE90-85B powering a Boeing 777-236ER on British Airways Flight 2276 suffered an uncontained failure during take-off roll leading to a fire. NTSB and FAA investigations were begun to determine the cause; initial findings were reported in September 2015.^[27][28]

On June 27, 2016, a GE90-115B powering a Boeing 777-300ER, on Singapore Airlines Flight 368, received an engine oil warning during flight and returned to Singapore Changi Airport. On landing the malfunctioning right engine caught fire, leading to fire damage to the engine and the wing.^[29]

Transfer gearbox failures

The FAA issued an Airworthiness Directive (AD) on May 16, 2013, and sent it to owners and operators of General Electric GE90-110B1 and GE90-115B turbofan engines. This emergency AD was prompted by reports of two failures of transfer gearbox assemblies (TGBs) which resulted in in-flight shutdowns (IFSDs). Investigation revealed that the failures were caused by TGB radial gear cracking and separation. Further inspections found two additional radial gears with cracks. This condition, if not corrected, could result in additional IFSDs of one or more engines, loss of thrust control, and damage to the airplane. The Airworthiness Directive requires compliance by taking remedial measures within five days of receipt of the AD.^[30]

Specifications

Derivatives

GEnx

The GEnx engine, that has been developed for the Boeing 787 Dreamliner and 747-8, is derived from a smaller core variant of the GE90, but features a fan with swept rotor blades.

GP7000

GE Aviation has also set up a cooperative venture with Pratt & Whitney, named Engine Alliance, under which the companies have developed an engine for the Airbus A380, named GP7000, based on an 0.72 flow scale of the GE90-110B/115B core.

GE9X

In February 2012, GE announced studies on a 10% more efficient derivative, dubbed the GE9X, to power the new Boeing 777-8X/9X aircraft.

LM9000

The LM9000 is an aeroderivative gas turbine available in two options; the LM9000 without water augmentation outputting {{cvt|66|MW}} at a 42.4% efficiency before cogeneration, and the LM9000 with water augmentation outputting {{cvt|75|MW}} at a 42.7% efficiency before cogeneration.^[36] The engine's 33:1 pressure ratio comes from a 4 stage low pressure compressor followed by a 9 stage high pressure compressor, driven by a 2 stage high pressure turbine and a 1 stage low pressure turbine, powering a 4 stage Free Turbine.^[37]

See also

• General Electric GEnx
• Engine Alliance GP7000
• General Electric GE9X

• Pratt & Whitney PW4000
• Rolls-Royce Trent 800
• Rolls-Royce Trent XWB

• List of aircraft engines

References

Notes

External links

• {{official website|http://www.geaviation.com/commercial/engines/ge90/}}
• {{cite press release |url= http://www.geaviation.com/press/ge90/ge90_20041116.html |title= It's Great Design Too: World's Biggest Jet Engine Fan Blade at The Museum of Modern Art |publisher= GE Aviation |date= November 16, 2004}}

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