Part players who will help cut costs

Industry forecasts appear to have reached broad consensus on at least one prediction – Middle East air traffic will continue to grow at extremely healthy, even spectacular rates, for the next two decades. The Airbus global forecast, for instance, anticipates year-on-year growth of 6.5%, requiring the region’s commercial jet fleet to triple to more than 1,600 aircraft, while additionally, the Rolls-Royce 20-year Outlook anticipates regional demand for a similar number of new business jets.  

The situation creates some interesting dynamics as the delivery of state-of-the-art equipment is accompanied by demands for ever more inventive ways of reducing operating costs. It’s against this background that the specialist area of component repair has turned into a battleground for the MRO providers.  

MTU Maintenance is researching innovative repairs for blisks being developed for next generation single-aisle aircraft

The agreed industry ballpark appears to be that, on average, a repair costs around one third as much as a replacement part, and often goes on to achieve longer service life. Little wonder the major players are committing serious levels of resource in the drive for repair innovations.  

Pratt & Whitney, for instance, has a team of around 300 specialists dedicated to developing new repair solutions, and claims that initiatives delivered by its SAVE (Scrap Avoidance and Value Engineering) clinics, have already identified $100 million worth of potential savings to customers. 

“As a leading OEM, we can define much more complex repairs for our own engines. We’re capable of levels of sophistication that others can’t match,” said Lynn Gambill, director of P&W Global Services Engineering. This has even led P&W to offer design enhancement rather than straight repair on some old parts where a significant cost of ownership benefit is identified.

P&W’s starting point involves analysing scrapped parts, concentrating on high-volume, high-value components, followed by a detailed project evaluation carried out in conjunction with the customer. Pratt says it takes anything up to six weeks to assess potential new repairs on its own products, although evaluations involving other manufacturers’ engines can last several months. P&W is targeting an increased share of CFM56-5 and –7 overhauls, which Gambill describes as “a definite growth opportunity”. New overhaul shops being opened by P&W in China and Turkey this year will both be CFM-capable.

Meanwhile, MTU Maintenance, whose customers include Saudi Arabian Airlines, Saudi Aramco, Qatar Airways, Royal Jordanian and Abu Dhabi Aircraft Technologies (ADAT), have even embraced the repair revolution as part of their branding, using the motto “Repair Beats Replacement”. MTU’s search for new repair schemes involves teams in Berlin, Hanover and Munich funded by an annual R&D budget of €10 million.

Arc cleaning high-pressure turbine vanes at Lufthansa Technik, where researchers develop around 50 new major repair schemes a year

“Our strategy is not to come up with ‘me too’ repairs,” declares Bernd Kriegl, director engineering, Commercial MRO at MTU Aero Engines. As an example, he cites repairs involving low-pressure compressor blisks (one-piece bladed discs), which have normally been viewed as replacement-only components. Developments in milling techniques and advanced welding methods initially allowed blade tips, as well as leading and trailing edges, to be treated. Now, as more processes evolve, the range of repairs is being extended to include replacement of entire blisk blade sections.

Pratt & Whitney has also patented blisk repair schemes; another segment identified as an area of “key focus” by Gambill and is using linear friction welding to replace whole blades.

New repair procedures, like engine development programmes, will typically pass through a series of formal approvals. MTU Maintenance has a procedure that requires seven “gates” to be cleared in sequence, starting with confirmation of a repair’s objectives and ending with a full process and quality review several months after production release. Depending on the complexity of the repair, clearance can take between six months and two years, although in exceptional cases involving advanced technologies and rigorous certification testing, it can be longer. MTU’s blisk initiatives, for instance, took between two and four years to clear the gating process. 

The ability of history to shape corporate character is illustrated in this sector by Lufthansa Technik (LHT). “Psychologically, because we originated as Lufthansa’s technical support arm, I believe we’re able to get closer to the airline point of view,” said Thomas Böttger, head of Customer Support and Product Sales, Engine Services at LHT. “We’re not an OEM, so we try to differentiate. If the only option is to buy a new OEM part, we look for an alternative. Is a repair possible? Is the technology available, and how much resource will be needed?”

Pratt & Whitney says new repair schemes developed through its repair clinics could deliver savings worth
$100 million to customers

Parts availability is also factored in. For instance, if a high-value component is scarce, and that situation is likely to persist, the case for investment in developing a new repair is strengthened. Conversely, the ready availability of used parts would have the opposite effect. 

Development of new repairs is the responsibility of LHT’s 90-strong Engine Parts and Accessory Repair (EPAR) team, based in Hamburg, with around 50 significant new schemes being produced every year. Two examples which typify LHT’s approach involve a new anti-friction barrier, developed with subsidiary Lufthansa Technik Intercoat, to treat CFM56 splitter fairings, and a thermal barrier coating for V2500 combustion chamber fuel nozzle guides.

According to LHT, neither of the OEMs offered a repair, but in both cases LHT’s own solutions are claimed to have cut scrap rates and made available a repair with longer life than a replacement part, at a third the cost.

However, LHT, which recently signed broad-based support deals with National Air Services of Saudi Arabia, and Saudi’s newest low-fare carrier Sama Airlines, said developing new repair solutions has to be balanced with more immediate issues in the Middle East, such as the number of engines coming off wing early. Focus is on intervention between overhauls to increase time on wing as sand ingestion continues to be a common cause of disruption, particularly affecting combustion liners and blocking cooling passages in HP turbine blades.

Realistically, none of the rivals can afford to ignore the levels of R&D required to push the boundaries on repair solutions. In fact, as P&W’s Gambill points out, advancing the science of repair is imperative, with specialists in ever-wider demand, evidenced by their integral role within the product design team behind the PurePower geared turbofan series.

“Experience in the field means we are aware of aspects such as distress modes, which allows us to anticipate future repair needs. For instance, that may lead us to recommend an optimum thickness for a blade root, resulting in longer on-wing life. Even before a new engine enters service, our input can be a vital part of driving down lifecycle cost,” Gambill said.