The number of CFM LEAP engines in the air is about to increase rapidly, both through aircraft returning from grounding and from new deliveries. Bernie Baldwin finds out about the MRO services in place for these developments.

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The CFM56 has been an engine family so seemingly ubiquitous in aircraft propulsion that its successor, the LEAP (Leading Edge Aviation Propulsion) family, still feels like it’s in its infancy. Yet it is almost 13 years since the programme was launched – and this year the LEAP‑1A will celebrate five years in service, on 2 August.

Also this year, the LEAP family’s operational presence in the market – on the Airbus A320neo and the Boeing 737 MAX – is scheduled to be expanded by the introduction into service of the Comac C919. And, of course, 737 MAX aircraft – powered by the LEAP-1B – are once again being delivered to operators following the aircraft’s grounding. 

While these new aircraft join the global fleet, there will also be significant numbers of LEAP-powered A320neos and older 737 MAXs coming out of pandemic-driven storage and returning to service, which is bound to have an effect on the amount of LEAP maintenance work when compared with what might be considered a ‘regular’ level of maintenance.

Lufthansa Technik’s senior vice-president of engine services Dietmar Fokke confirms that for these aircraft, in particular the 737 MAX and the LEAP-1B engines, the return to service requires specific maintenance tasks to be performed. 

“These tasks can include software updates, oil exchange and visual inspections, and normally do not require the engine to be removed from the aircraft or to even be disassembled,” he explains. “However, the performed maintenance tasks can lead to findings requiring further MRO work, hence it is beneficial to have a qualified MRO company under contract. Lufthansa Technik has therefore started preparation on the LEAP-1B to support our customers.”

After their storage, the A320neo family aircraft powered by LEAP-1A engines require similar maintenance work as the aircraft are likely to have been parked for a long period of time. “Again, during the checks further findings can occur, hence making it beneficial to have a contract with a MRO company,” Fokke says. “In general, an increased amount of necessary maintenance work can be expected due to the large number of aircraft and engines returning to service. The more extensive maintenance work, however, can be flexibly postponed due to the reduced utilisation and deployment of aircraft. 

“Furthermore, airlines are able to swap engines between their aircraft fleet while not all aircraft are being utilised. This allows the deferral of more extensive and expensive maintenance work for the moment and may result in a tense MRO availability and capacity situation in the future as a wave of maintenance work builds up.”

MTU Maintenance is also ready for the task of all these LEAP engines re-entering service, but has its own take on the extent of that challenge. “As this engine is still comparatively young, MRO tends to be focused on on-site services such as smaller fixes and BSI inspections or quick-turn visits,” comments Marcel Gerth-Noritzsch, head of engineering at MTU Maintenance Zhuhai. 

“This has not changed due to the storage of the fleet. Engine storage requirements and checks prior to re-entry into service are regulated by the OEM engine manual. We will be supporting our joint venture partner China Southern with their fleet wherever necessary.”

MTU Maintenance Zhuhai introduced the LEAP-1B into its portfolio in September 2019 and has had full disassembly, assembly and test capacity since autumn 2020. “We also carried out our first on-site activity, a lease inspection, for a LEAP-1B engine in summer 2020 and are currently in the process of introducing and obtaining certification for the LEAP-1A,” Gerth-Noritzsch reports. “Furthermore, MTU Maintenance Lease Services will be adopting LEAP engines into its spare engine leasing and technical asset management portfolio.”

Beyond this short-term pressure, MRO companies are also building long-term capabilities to maintain LEAP engines. They are designing support packages to bring benefits to customers which they believe can differentiate their MRO services on LEAP engines from those provided by their competitors.

“As with the around 30 other engine types in our portfolio, MTU Maintenance offers [LEAP] customers individual tailored and specialised solutions, catering entirely to their needs,” Gerth‑Noritzsch says. “We have short-term slot availability, fast turnaround times, competitive pricing structures and are able to adapt flexibly to airlines’ planning in this current market environment. 

“Our MTU Maintenance Zhuhai facility was one of the first MRO shops worldwide to obtain LEAP maintenance capability, and was the first MRO shop outside the OEM network that could provide quick-turn shop visits service to address any early technical issues in the LEAP fleet.” 

Lufthansa Technik was also quick off the mark in being one of the first engine MRO shops to provide services for the LEAP family and claims to provide a competitive alternative to the OEM. “We have already performed the first events at Lufthansa Technik in Hamburg,” Fokke confirms. “In addition, [we are] the first ‘CFM Branded Service Agreement’ (CBSA) holder, which includes extended licences, other commercial agreements and a strong technical cooperation with the OEM. 

“This enables us to continue to use our strength of developing our own MRO technologies and processes and to make use of our extensive knowledge, experience and engineering capabilities. This is with the aim and focus on tailor-made solutions to support individual customer needs, which in the end are aimed at reducing the total cost per engine flight hour (EFH).”

Fokke says Lufthansa Technik will offer competitive LEAP services covering the complete spectrum of engine MRO, from full performance restoration shop visits to on-wing support including in-house repair capabilities, ‘wing2wing’ and coverage of the complete engine life cycle. “We’re also building up worldwide mobile engine support services for LEAP engines in order to avoid shop visits,” he adds.

With new technologies, of course, new repair techniques and processes are often required. And there have been some changes needed to maintain LEAP engines compared with the CFM56.

“Since the LEAP engine is still a new engine type, many of the new repair techniques and processes are still under development,” says Fokke. “Many of the basic repair processes can be transferred from the CFM56. On the other hand, newly introduced materials and parts do require new repair techniques and processes. Examples of new material and parts are in areas such as composites [for example, the new LEAP engine fan blade requires completely new approaches for its repair], ceramic matrix composites (CMCs) and blisks.

“In addition, new technologies and repair processes have been developed and are available for the new engine types, such as cold-gas-spray.”

Fokke notes that Lufthansa Technik has begun a multi-million Euro investment to build its repair capabilities for LEAP engines, mainly at its facilities in Hamburg, Germany and Shannon, Ireland. “Some of the new repair technologies we are focusing on are multi hole laser drilling/HiY (high yttrium) 3-layer thermal barrier coating for the combustion chamber, but also new CCW14 shot peening and corrosion coating procedures for specific parts of the engine,” he explains.

“In April 2020, for example, the first LEAP-1A in Hamburg was dispatched for a quick turn. A first inspection of the engine revealed damage to the anti-erosion coating on the fan blades, which is not only an important protection, but also needed to maintain aerodynamic efficiency. As part of our repair activities, a successful repair method was developed and applied within just four weeks, resulting in a cost and material efficient application method for the coating repair of the LEAP-1A fan blades.”

At MTU Maintenance, Gerth-Noritzsch also emphasises that LEAP engines are still very young. “Only a limited number of repairs have been released in manuals,” he states. “However, conventional repair techniques and processes can also be applied to LEAP engine components. In fact, this philosophy was adopted by the OEM during the design phase in order to maintain high reliability for their new products.”

Gerth-Noritzsch highlights MTU Maintenance’s position as “engine experts” and discloses that as more and more repairs are released in the manuals, the company will actively adapt its experience and expertise from other engine types to the new repair techniques and processes introduced on LEAP engines.

One of those new technologies involves 3D-printing/additive manufacturing in which CFM’s parent companies – GE and Safran – each developed considerable expertise. According to Fokke, Lufthansa Technik shares the vision that additive manufacturing will play an even more important role in the production of parts and in the MRO industry. “We see that already certain parts, for example the swirler of the fuel spray nozzle, are being produced by this technique,” he says. “We can imagine that some of these manufacturing processes will also become available for LEAP engines.

“We believe, however, that this technology and manufacturing process needs to mature further, taking more than five years in time before being used for the manufacturing of parts in higher quantities. Lufthansa Technik sees the potential and the advantages regarding the cost, time and resource effectiveness, as well as design flexibility that additive manufacturing will offer.”

The company is already making use of additive manufacturing for the repair of parts for legacy engine types, Fokke says. “In addition, we have invested further into additive manufacturing and built up a centre of excellence specifically focusing on the development, manufacturing and repair of parts until production maturity. The focus is on rapid prototyping, tooling, repair and direct manufacturing. Based on our strong technical collaboration with the OEM, we can bring in our extensive knowledge and experience concerning development of new processes and technologies.”

There may be a busy time coming with the reintroduction of stored and/or grounded LEAP-powered aircraft, but the industry has prepared well for that. And plans to support the vastly increased numbers of engines for many years ahead appear well advanced, too.