While additive manufacturing, including 3-D printing, is emerging as a method OEMs may commonly use in the near future to produce specific components for new aircraft—with some 3-D-printed parts already flying in engines—the technology may also be on the verge of revolutionizing MRO. In addition to spare parts being 3-D-printed on demand, they might also be repaired with the method—and both uses offer an attractive business case.
Satair Group, thesubsidiary that specializes in the distribution of spare parts, offers plastic spares made via additive manufacturing. It uses materials such as polyamide, acrylonitrate-butadiene styrene (ABS) and thermoplastic polyurethane. It makes sense when a conventional method would involve a long lead time or a complicated supply chain, or when the part is out of production, Stephan Bloempott, Satair Group’s head of additive manufacturing, tells Aviation Week.
An extra advantage over a straightforward replacement is that additive manufacturing enables the production of a customized component for an in-service fleet. For Jetstar’s Airbusfleet, Satair designed a new blanking plate for seat armrests (the need stemmed from the removal of an inflight entertainment interface). There were only a few aircraft to equip. Therefore, conventional methods, possibly involving expensive molds, would have been uneconomical. “So we ‘printed’ the cover, which now flies on A330s,” Bloempott says.
The cost of an additive manufacturing machine is still very high, however, at €500,000-1 million ($525,000-1.05 million). “It only works with a very good machine utilization,” Bloempott says. The next generation of machines, available in 2-3 years, is expected to be much more productive.
When additive manufacturing becomes widespread in MRO, it will facilitate the shrinking of inventories. “If I can print efficiently, I save in inventory,” Bloempott points out.
The strength of the business case for 3-D printing in MRO depends on the number of parts required. On a cabin part, conventional casting of plastic can be economical for the manufacture of 60-70 parts, estimates James Kornberg, innovation director forIndustries Engineering & Maintenance. But the cost of additive manufacturing is decreasing very quickly, he says: “The cost of an additive manufacturing machine has plummeted and the trend [continues].”
has yet to manufacture any parts for MRO purposes. But it is just a question of time, according to Thierry Thomas, vice president of Safran Additive Manufacturing. “These processes are still very expensive, but their profitability threshold will evolve with the productivity of the machines,” he says. “What I could say today about additive manufacturing costs may be obsolete in six months.”
Although it is still costly, additive manufacturing can already be exploited for its agility, Thomas emphasizes. This can be the case when a tool is no longer available or if producing it again might disturb an already busy supply chain, Thomas says. “Three-D printing can solve a lead time issue,” Kornberg concurs.
is using 3-D printing to replace obsolete cabin interior plastic parts on early /72s. Some molds are no longer usable because related techniques were abandoned. “We can make a single part without having to launch the manufacture of a series of 200,” says Stephane Marty, ATR’s head of cabin design. A 3-D-printed polyesterimide part passed the flammability test, and ATR is awaiting the imminent first “flyable” component.
Additive manufacturing is gaining ground in terms of usable materials. Three-D printing is about to be technically mature for titanium, a metal of great interest in aeronautics, and this opens a field of possibilities.
Satair, which had been using 3-D printing for plastic spare parts only, is starting to use titanium in additive manufacturing, beginning with tools, and ground support equipment. “We selected 60 tools, and we changed from casting, for instance, to 3-D printing,” Bloempott explains. An example is a spherical location tool, used to align pins in a landing gear. It is now made of a single part instead of 14. The design is more efficient, and the lead time if the tool is not in stock is shorter for the customer.
Another example is a safety collar to immobilize a high-lift device for maintenance. Usually, it is a machined titanium part. “It is difficult to machine and wastes a lot of material,” Bloempott says. Satair did some topology optimization, meaning it removed material where it is not needed to withstand a load. “We saved 50% of weight and rounded all edges,” Bloempott says. As it is lighter, the tooling is easier to use. And as the edges have been rounded, it does not necessarily damage the wing if it falls. Both tools are now in use.
What about flyable spare parts? Bloempott predicts the first ones will be made early in 2017. “We can rely on Airbus qualification processes for titanium,” he says. Last fall, titanium printing was qualified on an Airbus printer. The (EASA) approved the so-called major modification. “To start with, we will manufacture nonloaded parts,” Bloempott explains. Satair and Airbus will thus gather experience, notably in adapting the design to the process. A prototype bracket for a crew rest compartment has been manufactured. Another candidate is a part for an Airbus pylon.
ATR is experimenting with a 3-D-printed titanium filler for a hollow situated on the wing’s leading edge. It would avert water ingress and resulting corrosion. “We do not offer a service bulletin yet, but we have just installed the part on our test aircraft,” says Vladimir Camuzard, ATR head of structures support engineering.
New prospects are emerging in component replacement. As Satair did with tooling, an airframer may redesign a part, optimizing it for its role rather than for its manufacturing process. ATR is considering replacing several damaged parts with one single part, which would reduce repair time. It would also cut the number of interfaces between parts, making cracks less likely. ATR is counting on collaboration with third-party additive manufacturing experts to select suitable areas on the airframe; the task is to begin early this year.
Rather than being replaced, a damaged part may be repaired. This is what France-based BeAM is offering with its directed energy deposition (DED) technology. “A lot of parts could not be repaired because welding carries so much energy that it changes the structure of the part,” says BeAM Chairman Emeric d’Arcimoles. “Our technology brings just enough energy to melt the powder.”
A cooled turbine blade, for instance, may one day be manufactured via selective laser melting (SLM), a longer-established process. But DED might be used to repair such a blade, whatever its manufacturing process. “We are performing qualification trials for blade repair, and the first repair of a flyable blade may take place in 2017,” d’Arcimoles says.
BeAM not only sells DED machines, it also helps the customer design a part for the technology and simulate the manufacturing process. It then creates a dedicated machine and trains the customer’s engineers. As the technology is tricky to master, a number of universities are buying BeAM machines to support their industrial partners, d’Arcimoles adds.
In fact, BeAM is betting on an open approach, sharing know-how with the customer and with the ecosystem around it to stay at the edge of innovation.
Associating the DED and SLM processes may drastically cut the cost of 3-D printing, d’Arcimoles suggests. “SLM is suitable for a small, complex part that used to be made of several parts but it is costly, as SLM involves recycling a large amount of powder.” Combining the two processes, manufacturing could start with SLM as the base; then functions could be added through DED. The latter uses a small quantity of powder, so total cost would be slashed while the lead time benefit of 3-D printing would be kept.
Done another way, DED could be linked to metal forging. “In terms of metallurgic structure, DED is better than casting but inferior to forging,” d’Arcimoles says. The idea is to use DED to add functions to forged parts. The final component can be complex, but its critical part can have superior metallurgic properties, while requiring only simple forge tooling.
Companies besides OEMs may want to use 3-D printing for spare parts, thus creating a new headache for airframers, engine-makers and other equipment manufacturers. Numerous companies have long been in business manufacturing non-OEM spare parts. But now manufacturing becomes much easier and the upfront investment will be drastically reduced. This opens the door to an onslaught of established MRO service providers and newcomers, all looking to offer lower-price parts. Should OEMs accept the new situation and look for a win-win arrangement? Or should they build barriers to maintain their dominant position in spare parts manufacturing?
Additive manufacturing is creating a business model shift, d’Arcimoles contends. OEMs—especially engine-makers—usually sell spare parts to earn big money after having sold original equipment at rock-bottom prices. “Some OEMs tell us they will stand in the middle and keep everything under control, selling repair licenses,” d’Arcimoles says. But others want to “build a wall and continue to sell spare parts,” thus risking that some companies may try to bypass them.
Safran’s Thomas does not object to letting authorized MRO service providers operate 3-D-printing machines to make Safran parts. “We will have to assure quality,” he notes.
ATR even sees an opportunity. A spare part could be manufactured closer to the customer. An MRO service provider may be equipped with a 3-D-printing machine or linked to a local partner for 3-D printing, Camuzard says.
Air France Industries Engineering and Maintenance (AFI KLM E&M) is already using 3-D printing for prototypes, tooling and parts. A prototype part for an engine may be 3-D-printed for shape and size validation. It will later be manufactured with a conventional process. AFI KLM E&M is 3-D-printing patch prototypes that will be used to define the design of the final part to repair a-80C2/E1 turbine rear frame. The prototype of a seat track cover has also been validated using 3-D printing, says Kornberg.
The actual parts Air France Industries KLM E&M manufactures with additive manufacturing are not critical, as they are cabin parts. The company is studying the use of laser cladding on some engine components.
“We cooperate with the OEM on a number of subjects,” Kornberg emphasizes. In fact, even though cooperation is not always mandatory, it is most often preferable. For example, a lessor may require the airline to use authorized parts and repair processes.
Satair is considering spreading the use of additive manufacturing upstream in its supply chain. “We will enable our suppliers to adopt the technology so the airline is benefitting,” Bloempott says. He expects higher availability of parts. The plan is to help suppliers with the specifications of the materials and processes. “Satair and Airbus will gradually involve more and more suppliers in the qualification,” he adds.
Will aluminum fit 3-D printing?
Not all experts in additive manufacturing are on the same page for the usability of aluminum. Vladimir Camuzard, ATR’s head of structures support engineering, asserts that 3-D printing of aluminum is technically doable—but hardly economical for simple shapes. The feasibility of using aluminum in additive manufacturing is recent, as it has evolved from “impossible” to “difficult” in just one year, according to Thierry Thomas, vice president of Safran Additive Manufacturing.
In BeAM’s “directed energy deposition” process, aluminum disturbs the laser beam and so is not currently usable. “But we are working on it; this is pure metallurgy,” chairman Emeric d’Arcimoles says.
Certifying 3-D Printing
“From a certification standpoint, switching to additive manufacturing is like changing material,” says Thierry Thomas, vice president of Safran Additive Manufacturing. Indeed, the material is created during the manufacturing process. He reports progress with EASA and the. “We have a much clearer view of certification requirements,” he says. A few parts for new engines—for example, a fuel nozzle on a helicopter turboshaft—are expected to be certified soon.
“An MRO service provider has to develop a stable process,” says Simon Waite, an EASA senior expert in materials. “An MRO may miss that unless it works directly with the type certificate holder.”
In other words, having EASA production and design organization approvals, such as most large MRO service providers have, may not be enough. “Certification is also about criticality of the part and working with the type certificate holder,” says Waite.
EASA believes the regulatory framework already exists, except for some fine tuning. “A minor change in process or material can have a major influence on a part failure mode and therefore on the size of the debris downstream, for instance—this is the gray area we are working on,” Waite explains.
EASA is taking “a cautious approach” to the entry of this technology into the aviation industry. As it is still in its infancy, the agency is going as deep as requiring the serial number of the 3-D printing machine. “Manufacturer or MRO, they have to show they have control of the machine,” he says.
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