A collaboration between the U.S. Air Force, GE Additive and GE Aviation focused on the acceleration of metal additive manufacturing for the sustainment and operation of aircraft has reached a significant milestone. The partners recently initiated Phase 1 of the joint program, and have already 3D printed a metal sump cover for GE’s F110 engine used on both F-15 and F-16 aircraft. The next phase of the collaboration will focus on producing a sump cover housing assembly.
Last year, GE Additive and GE Aviation reached out to the U.S. Air Force with a proposal to explore additive manufacturing for its sustainment, readiness and affordability requirements. This initial conversation developed into a joint program between the two GE businesses and the U.S. Air Force’s Rapid Sustainment Office (RSO), which is responsible for increasing mission readiness by identifying, adopting and scaling new technologies for the operation and sustainment of its fleet.
One of the key things that the RSO is tasked with is efficiently sourcing and producing spare parts for aircraft. It is no surprise that metal AM ended up on the roster for potential technologies to address spare part production: the technology’s agility and speed have made it interesting for spare parts production in many industries. GE, with its extensive experience qualifying and certifying 3D printed metal parts for the aviation sector, was therefore an ideal partner for the RSO.
Agility and speed
“The collaborative effort between the U.S. Air Force and GE shows great promise toward the adoption of metal 3D printed parts as an option to solve the US Air Force’s current and future sustainment challenges,” said Colonel Benjamin Boehm, Director of AFLCMC/LP Propulsion Directorate. “This capability provides an alternate method to source parts for legacy propulsion systems throughout their life cycle, especially when faced with a diminishing supplier base or when infrequent demands or low volume orders are not attractive to traditional manufacturers.”
Notably, the collaboration is the first time that GE Additive and GE Aviation engineering and supply chain teams have worked together for the benefit of an external customer. Together, the businesses are demonstrating to the Air Force the advantages of metal additive manufacturing for spare parts production. Chief among these benefits is speed, which is especially crucial in a defense setting. Traditional casting, on the other hand, can have lead times of up to two to three years for certain parts.
“The Air Force wanted to go fast from day one and gain the capability and capacity for metal additive manufacturing, as rapidly as possible, to improve readiness and sustainability,” explained Lisa Coroa-Bockley, general manager for advanced materials solutions at GE Aviation. “Speed is additive’s currency, and by applying our additive experiences with the LEAP fuel nozzle and other parts additively printed for the GE9X, being able to offer an end-to-end solution and also applying lessons learned of a robust certification processes, we’ve been able to accelerate the pace for the USAF.”
3D printed sump cover
The joint program is based on a “spiral development” model, a concept typically used to enhance software development but which can also be applied here to increase the complexity and scale with each project phase. In their work, the partners are upping the complexity throughout each phase by moving from simpler part identification, to part and family of parts consolidation, to complex components and systems, like common core heat exchangers.
The team recently initiated the first phase of the RSO program, which has involved the identification of GE Aviation spare parts for the F110 and TF34 engines and showcasing their airworthiness. Specifically, the first phase is building on preliminary work conducted by a GE Aviation team surrounding a 3D printed sump cover for the GE F110 engine used on the F-15 and F-16 aircraft.
“Compared to other parts on the F110 engine, the sump cover might have lower functionality, but is incredibly important,” said James Bonar, engineering manager at GE Additive. “It needs to be durable, form a seal and it needs to work for the entire engine to function – which is of course critical on a single engine aircraft like the F-16.”
The sump cover component is typically cast from aluminum, but the GE Additive and Aviation teams recognized the potential benefits of producing it using additive manufacturing. The first 3D printed sump covers were produced at GE Aviation’s Additive Technology Center in Cincinnati using Concept Laser M2 machines and cobalt-chrome material. “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,” said Melanie Jonason, chief engineer for the propulsion sustainment division at Tinker Air Force Base (AFB) in Oklahoma.
“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,” added Beth Dittmer, division chief, propulsion integration at Tinker AFB. “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 aircraft.”
With progress being made, the partners are preparing to move into Phase 1b, which will add complexity to focus on a sump cover housing: a family of parts on the TF34 engine that has been in service for over 40 years. Ultimately, the program aims to explore how additive manufacturing can shape the future of design, production and certification of parts in the commercial and military aircraft sectors.