U.S. Air Force Looks to Fly with 3D Printed Parts

Metal additive manufacturing is being applied to the production of oil lubrication system parts for the GE F110 engine, which powers the Air Force’s F-16 jet fighter.

Adopting new manufacturing technologies has often proven to be a game changer for companies seeking to enter a new market or retain their leadership in an existing one. For GE, 3D printing is the latest tool for staying ahead of its competitors in the aircraft industry.

Though GE engineers had originally developed the engine for the B-1 supersonic bomber, by 1970 it was no longer seen as a leading supplier. That opinion changed in the 1980s when GE designed a new engine around the B-1 core to provide the U.S. Air Force with propulsion systems for its F-16 and F-15 fighter aircrafts. Decades later, that F110 jet engine still powers most frontline F-16 fighters. 

To keep its fleet flying, the U.S. Air Force continually searches for the best ways to procure parts, including crucial spare parts for planes that have been in service for decades. That’s why the Air Force’s Rapid Sustainment Office (RSO) was receptive when representatives from GE Additive approached them last year with the idea of making some parts with 3D printing.

That collaboration is now bearing fruit. GE’s engineers are building a 3D-printed sump cover for the GE F110 engine. The sump is part of the oil lubrication system, and the sump cover is basically a cap, yet still a key part of the engine, says James Bonar, engineering manager at GE Additive. “Compared to other parts on the F110 engine, the sump cover might have lower functionality, but it is incredibly important. It needs to be durable, form a seal, and it needs to work for the entire engine to function. That’s critical, of course, on a single-engine aircraft like the F-16.” F110 engine. Source: GE AviationF110 engine. Source: GE Aviation

Intricate shapes
GE was able to make its case for 3D printing based on its broad expertise with 3D printing technology. Also known as additive manufacturing, the process works by fusing thin layers of metal powder with a laser or electron beam to make a final product. The technology allows engineers to create shapes that would otherwise be too expensive, or too intricate, to make by casting or stamping. 

According to Antroine Townes, site leader for GE Aviation’s Additive Technology Center (ATC), “The beauty and the value of additive manufacturing comes in the flexibility of design and the speed of innovation.” And it has been a particular boon for GE’s work in aviation.

Engineers at the ATC, for instance, were able to use the technology to combine more than 300 engine parts into just seven 3D-printed components in the new GE9X engine, which GE claims is the most powerful jet engine in the world. Thanks to 3D printing and other technologies, this engine is 10% more fuel-efficient than its predecessor, the GE90.

GE Aviation also relied on 3D printing for its Catalyst, the first “clean-sheet” design of a turboprop engine to make it to the aviation market in more than a half-century, according to GE Aviation. With 3D printing, GE’s engineers distilled about 800 parts down to a dozen or so, while reducing the Catalyst’s weight and improving its fuel consumption.

3D-printed sump cover 
GE’s collaboration with the Air Force RSO builds on this experience. “The Air Force wanted to go fast from day one and gain the capability and capacity for metal additive manufacturing as rapidly as possible in order to improve readiness and sustainability,” says Lisa Coroa-Bockley, general manager for advanced materials solutions at GE Aviation. “Speed is additive’s currency.” Additively manufactured cobalt-chrome sump cover for F110 jet engine. Source: GE AdditiveAdditively manufactured cobalt-chrome sump cover for F110 jet engine.
Source: GE Additive

The first print run of the sump covers, which are conventionally cast from aluminum, happened at the ATC, where engineers created the parts from cobalt-chrome powder using GE Additive’s Concept Laser M2 machine. 

“Part of that process involved exploring how to quickly eliminate the associated risks with castings, and how metal additive might replace it for those parts that are either no longer in production or where we need smaller production runs to keep our platforms flying,” explains Melanie Jonason, chief engineer for the propulsion sustainment division at Tinker Air Force Base in Oklahoma.

For this collaboration, the Air Force and GE are using a spiral development model common to fields like software. This process begins with lower functionality individual parts, like the sump cover, and then advances to tackle complex components and systems such as heat exchangers. With Phase 1a of the sump cover project underway, the teams are moving on to Phase 1b, which focuses on a sump cover housing—a family of parts on the TF34 engine. This engine powers the Air Force’s Fairchild Republic A-10 Warthog, which has been in service for more than 40 years.

“The program with GE is ahead of schedule and the preliminary work already done on the sump cover has allowed us to move forward quickly,” says Beth Dittmer, division chief of propulsion integration at Tinker Air Force Base. “As we build our metal additive airworthiness plan for the Air Force, the completion of each phase represents a significant milestone as we take a step closer to getting an additive part qualified to fly in one of our aircrafts.”

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