In the 1980s, when the U.S. Air Force opened up what is now known as the Great Engine War for propulsion systems to power its F-16 and F-15 fleets, GE saw its chance to again become a major supplier of power plants for fighter aircraft. Its engineers had developed the engine for the B-1 supersonic bomber, and they used its powerful and efficient beating heart — called the core — to design a new jet engine, the F110.
Today, the Air Force is searching for the best, nimblest ways to procure parts, including crucial spare parts, it needs for planes that have been in service for decades. 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 a cap —and a key part of the engine.
Challenge: Spare parts for readiness
The US Air Force’s Rapid Sustainment Office (RSO) is charged with increasing mission readiness by rapidly identifying, applying and scaling technology essential to the operation and sustainment of its fleet. With a significant number of aircraft soon entering their sixth decade of service, difficulties in sourcing and producing spare parts potentially represents significant risk.
GE’s experience qualifying and certifying additively manufactured metal components that meet the commercial aviation sector’s rigorous regulatory requirements was of interest to the RSO as the Air Force continues to shape its own metal additive airworthiness and certification path.
GE’s collaboration with the RSO has been the first time that GE Additive's and GE Aviation’s engineering and supply-chain teams have partnered for the benefit of an external customer. The Air Force wanted to:
- Go fast to gain the capability and capacity of metal additive manufacturing, as rapidly as possible, to improve readiness and sustainment.
- Explore how to quickly eliminate the associated risks of castings and investigate how metal additive might replace castings for those parts that are either no longer in production or where they need smaller production runs to keep our platforms flying.
The US Air Force and GE settled on a program based on a “spiral development” model (based on a concept often used to enhance software development) that increases in complexity and scale with each phase. In this program, complexity involves moving from simpler part identification, progressing to part and family-of-parts consolidation, and eventually tackling complex components and systems, such as common core heat exchangers.
The GE Additive team - headed by James Bonar - partnered closely with the GE Aviation team to build on the exploratory work on the sump cover, which was conventionally cast in aluminum. Bonar’s team ensured the robust design practices were met during the fine tuning of parameters and the dial-in process at GE Aviation’s Additive Technology Center (ATC) in Cincinnati. GE Additive Concept Laser M2 machines, running cobalt-chrome at the ATC, were used for the first builds of additively manufactured sump covers.
Phase 1b is already being planned in line with the spiral development model, adding complexity to focus on a sump cover housing, a family of parts on the TF34 engine - which has been in service for more than 40 years. As the program enters this next phase, the combined US Air Force and GE team finds itself at an exciting intersection: rapidly solving problems today for the US Air Force’s immediate readiness and sustainment needs, while turning its attention to tomorrow and how additive will advance and inform design, manufacturing and certification of things we’ve never seen before in the commercial and military aerospace sectors.