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Big fan MRO

After more than two decades in service, the GE90 appears to be performing better than ever. Paul E Eden discusses its MRO provision with OEM General Electric, AFI KLM E&M and MTU Maintenance

General Electric’s GE90 entered service with British Airways in late 1995. Offered as a Boeing 777 powerplant option alongside the Pratt & Whitney PW4000 and Rolls-Royce Trent 800, it remains exclusive to the big twin. And Boeing offers only the higher-rated GE90-110 and -115 variants for the 777-200LR, -300ER and Freighter; in its -115B variant, the GE90 is the most powerful in-service jet engine, rated at 115,300lb (513kN) thrust.


More than two decades after British Airways took its first GE-powered 777-200, Judd Tressler, GE90 Customer Programs Leader, GE Aviation, revealed statistics for the engines leading the GE90 fleet. The senior GE90-94B has 86,000 hours and 18,000 cycles, the lead -115B 55,000 hours and 9,000 cycles. “Engines typically run between 3,500 and 4,500 cycles between performance restoration shop visits, with variation depending on operational parameters and environment,” he says.


“The GE90-94B engines are approaching their third shop visit since the engine was introduced in 1995. For the -115B, which entered service in 2004, the family is approaching its second shop visit.” Off-wing maintenance requirements are described in the Engine Maintenance Manual, typically factoring in Workscope Planning Guide (WPG) recommendations. Their scope varies significantly, depending on why the engine was removed, inspection findings, intended time on-wing after a shop visit and so on. “GE provides a WPG to customers to share experience and recommendations for maintenance considerations when engines are returned to an overhaul shop,” Tressler explains.


Between its constituent airlines, Air France KLM operates around 20% of the in-service GE90 fleet. Air France Industries KLM Engineering & Maintenance (AFI KLM E&M) has therefore inevitably become what a company spokeswoman termed the ‘main alternative to the manufacturer’s services’.


“AFI KLM E&M’s offering is backed up by leading-edge technology infrastructure and the group has expanded its engineering capacity through a continuous investment programme. For example, we added a further 5,500m2 to our workshops in 2006 and 11,000m2 in 2010. The group has also developed unique ‘Quick Turn’ rectification operations.”


On-wing GE90 maintenance requirements and their timing are documented in the Boeing 777 Maintenance Planning Document (MPD) and Aircraft Maintenance Manual. Recommendations for additional targeted inspections or maintenance actions are made through GE or Boeing Service Bulletins. Tressler notes: “The MPD includes inspection recommendations for numerous engine components, including visual inspections of fan flowpath and engine mount hardware, borescope inspection of the combustor and high-pressure turbine hardware, and operational checks of controls and accessories hardware.”


At a very basic level, much of the on-wing maintenance task is about what an engineer can see, particularly signs of leakage and wear and tear. Engine performance may also be assessed, both AFI KLM E&M and MTU Maintenance, for example, employing proprietary engine monitoring systems.


GE90 maintenance requirements vary with model and hardware configurations, and operational demands between aircraft fleets. The same is true when comparing the GE90-90B (777-200ER) to the GE90-115B (777-300ER). Germany’s MTU Maintenance, a division of MTU Aero Engines, specialises in the -110 and -115B engines, as Norbert Moeck, Director Engine Programs MTU Maintenance explains:


“MTU Maintenance has been licensed to provide independent engine services for the GE90-110/-115B since 2010. We’re the number one independent service provider for the model, performing more than 20 shop visits per year, a number we only expect to increase in coming years. 


“Our individually-tailored solutions encompass innovative MRO services, integrated short- and long-term leasing, and asset management. They focus on minimising costs and maximising customer assets, and we demonstrate world-class turnaround times of less than 100 days. Our GE90 business is extremely important to us.”


Well matured?

The first of the higher-rated GE90s entered service in 2004, almost a decade behind the original series. With so much flight time behind it, has GE seen the engine deliver the performance it expected? “With more than 2,400 GE90s in service, the engine has outperformed our expectation,” Tressler says. “In fact, today’s GE90-115Bs have been enhanced to reduce fuel burn by 3.6% compared to the 2000 launch specifications.” >>

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