When MTU and Lufthansa Technik joined forces to establish EME Aero – an overhaul shop for Pratt & Whitney PW1000G engines near Polish city Rzeszow – they targeted a flexible layout with optimal process and material flows that would avoid any repeat of mistakes from the past.
Like other MRO providers, MTU and LHT had once used flow lines in which engines would move at a defined pace through different work stations, and wanted to replicate the efficiency gains automotive manufacturers had realised through their moving production lines.
At its Hannover shop, MTU established a flow line in which engines move through workstations on a moving floor. LHT subsequently, in 2009, opened a newly built Hamburg shop that featured a bespoke, rail-based crane system in the ceiling, from which engines were suspended on chains.
Such systems have enabled MRO providers to process greater engine volumes. But the flow principle is vulnerable to disruptions and provides limited flexibility when processes do not go according to plan. What might work like a clockwork in the assembly of predictable, factory-new products turned out to be less suitable for maintaining used engines with varying repair requirements.
“Many flow lines… are not operating as they should,” EME Aero chief executive Derrick Siebert tells Cirium. “The weakness of the flow is whenever you have disturbances or deviations from the standard, then you have to stop to [resolve the issue], and then the whole thing stands. This is a vulnerable point in MRO because you always have different [findings],” he says.
Siebert, who joined EME Aero from LHT, was involved in the design of the MRO group’s Hamburg engine shop. The greenfield project in Poland, he says, represented an opportunity to “challenge everything” in terms of shop design conventions and incorporate “all learnings and best practices from our shareholders… to avoid mistakes of the past”.
The new shop will include a flow line in which engines move through different disassembly and assembly stations. But crucially, that system will not be based on permanently installed structures like a moving floor or overhead engine suspension system. Instead, engines will be fitted to freely moving, floor-based carriers that can be pulled in and out of the production line, without disturbing the overall flow.
MTU developed for its PW1100G assembly line in Munich a bespoke system of freely moving, motorised carriers rather than adopting the US manufacturer’s assembly principle whereby engines are being suspended from an overhead structure.
Beyond sharing the basic idea of a mobile, ground-based unit, the carriers used in Rzeszow – dubbed mobile transport overhaul stands (MTOS) – are quite different to the ones used in Munich. Engines attach to MTOS, via an adapter, at a single hoist point. The same principle and adapter is used to attach the engine to fixed overhaul stands (FOS), which have been designed especially for EME Aero.
Usually during shop visits, PW1000G engines are suspended from a horizontal beam supported by two stands located either side of the engine’s central body. A similar, smaller arrangement is used to support the engine’s turbine section. That set-up restricts engine access and also complicates the disassembly process as stands need to be detached and reattached to the engine at different points as modules are removed, Siebert says.
He describes that process as “not very comfortable” and “unpractical”, and says that MTU and LHT therefore decided “we need something different there”. Prior to EME Aero’s construction, both shareholders had started servicing PW1000G-series engines at their own shops.
Each FOS is capable of holding two engines at a time from arms stretching out sideways from the central floor fixture. EME Aero started operations with the static stands in January 2020. An initial two MTOS units are scheduled to be introduced to the shop in early 2021.
Siebert says, however, that the mobile carriers still need to demonstrate efficiency gains over the stationary stands. “At the moment, we are so happy with the FOS. It exceeds all our expectations in terms of ergonomics, safety and helping to reduce process time,” he notes.
The number of MTOS units has not been finalised. “We are still in the concept phase,” Siebert says. “We need to investigate the final flow line… and how the whole system of FOS and MTOS is working together.”
Nevertheless, he thinks the combination of a flow line with stationary stands – crucially without permanent infrastructure that could determine the shop’s basic layout – is a “game changer”. He adds: “The area where our flow line is, is just [made] of concrete. If you decide not to do the flow line anymore, you can do anything else.”
EME Aero chief operating officer Robert Maslach foresees that the company will use a hybrid model of using mobile and static stands.
Operations at the site have so far concentrated on the PW1100G, an option for the A320neo family. In 2021, the shop is scheduled to additionally start servicing PW1500Gs, which power A220s. The Embraer 190/195-E2-powering PW1900G is to be added to the shop’s capabilities later on.
While there are differences in the dis- and reassembly of these engine models, Maslach says EME Aero designed processes and tooling with to be as similar as possible in order to increase efficiency and flexibility. Around two-thirds of tooling is interchangeable between engine models, Maslach says. “This creates a lot of freedom and space on the shop floor.”
Engine module stands and fixtures to handle large engine parts have been equipped with batteries to support operations independently from power points in the facility. “This is a concept that is paying off well because especially in the beginning you try something; you change; [you] take something out, put it somewhere, without having to do the hardwiring,” says Siebert.
NEW OVERHAUL MODEL
Like other PW1000G overhaul shops in the OEM’s aftermarket network, EME Aero concentrates solely on dis- and reassembly, and engine testing. Component repairs are conducted by a specialist supplier network governed by the manufacturer.
The objective for the overhaul shops is to standardise processes as much as possible. Siebert notes that while other overhaul shops support different engine types and manufacturers, EME Aero can concentrate on a single engine family. Still, despite commonality between the engines, Siebert says, “we do see big differences in the findings”, some of which lead to “totally unplanned” shop activities.
Noting that in-service PW1000G engines have not yet reached a mature age, he says: “You have to maintain broad boundaries in MRO to define a standard.” Concentration on engine dis- and reassembly and testing has reduced complexity in shop processes and, Siebert says, “performance of the [part repair] network so far is good”.
Maslach does not rule out the possibility that “question marks could come [up]” about the new model of using external repair providers, especially when overhaul volumes increase and supplier management could become more demanding. But Siebert cautions: “Don’t be mistaken, even if you do a repair yourself, it still remains a challenge to get it back on to the engine in time.”
Siebert says EME Aero’s “only wish” today is to have access to more repair processes in order to reduce part scrap. “With legacy, mature engines, of course, you have more available repairs.” He acknowledges that the PW1000G repair network is “still developing”.
Despite the downturn, EME Aero operates at “full load”, Siebert says, adding: “We have nothing to complain about.” Airlines have tended to deploy new aircraft, like the A320neo, amid the crisis, firstly because of their fuel efficiency versus older equipment, but secondly because maintenance for new engines is typically covered by manufacturers’ warranty during their initial operating period.
This will likely have favoured MRO shops servicing new engine types, like EME Aero.
Maslach says the shop had inducted 42 engines by 4 December, and will take in another four by year-end. The site has a staff of around 400, and will, its owners envision, handle more than 450 shop visits per annum from 2026.
On 10 December, MTU disclosed an agreement with International Aero Engines LLC – an IAE subsidiary established to set up a support network for the PW1000G series – to expand the German programme partner’s MRO activities under the OEM’s aftermarket support programme. MTU says it will handle “a significant quantity of shop visits per year in addition to [its] existing and substantial commitments to the programme” under the new 11-year deal.
Noting that “a lot of MRO capacity” had been established by P&W and its partners for the PW1000G series prior to the pandemic, Siebert acknowledges that an overhaul ramp-up will likely be delayed. “Airlines are postponing deliveries… so growth we expected has also been postponed,” he says. “The [MRO] capacity will be there, and the question is: will the engines be there. That’s a challenge. A bump that we might have to overcome.”
Still, Maslach expresses satisfaction that operations were established at the site “without any big issues”, despite restrictions due to the pandemic. Approvals for new processes designed especially for EME Aero were remotely granted. “The coronavirus was quite well mitigated,” he says.
This analysis was written by Michael Gubisch, part of Cirium’s London-based reporting team