F-15 in Okinawa: 3D printing shortens downtime with an on-site printed cooling-air duct

Additive manufacturing is increasingly seen by armed forces as a tool to sustain maintenance at forward locations when supply chains are slow or spare parts are unavailable. The NAVAIR additive-manufacturing team supports Marine Corps and Navy maintainers with training, engineering support, and technical data packages so repairs can be carried out even under contested logistics conditions.

A recent example comes from Kadena Air Base in Okinawa. There, U.S. Air Force technicians discovered a crack in the right cockpit cooling duct of an F-15 Eagle after a flight. The initial assessment assumed a grounding of three to four months because the component could not be sourced quickly. First, they tried to preserve as much original material as possible using conventional methods. After consulting with a Depot Liaison Engineer, the decision was made to replace the part additively.

“We were skeptical of the first design provided by [the MALS] due to the significant shorter print time compared to our first prints. Our techs learned that the duct’s orientation affects the necessity for the support structures, which allowed the Marines to reduce the duct’s print time without compromising its structural integrity,” he said.

In practice, iteration was still necessary here as well: the 18th Maintenance Group (18 MXG) maintenance team first printed two prototypes, but ran into technical issues before a part met the specification.

“Here was a situation where a multi-million dollar aircraft was going to be sidelined for months due to the lack of a part in the supply system,” NAVAIR Additive Manufacturing Program Manager Theodore Gronda said. “The Air Force’s proactive, forward-leaning maintainers sought and obtained approval to repair the part using their on-site AM capability. 18 MXG was backstopped by MALS-36’s AM capability and they even got a better and quicker AM design out of the collaboration.  This was truly a glowing example of a ‘One Team, One Fight’ effort.”

What proved decisive afterward was the collaboration with Marine Aircraft Logistics Squadron 36 (MALS-36), which had the same printing system. In less than 12 hours, prototypes were manufactured, delivered, and test-fitted on the aircraft. After analyzing the technical data package, the Marines also optimized the print layout: the part’s orientation reduced support structures and shortened print time by two hours without compromising mechanical integrity.

Carrillo sees the outcomes of this effort going beyond a single aircraft and the Air Force. “The duct’s new printing requirements are now part of the Air Force’s AM technical publications and will be used for similar repairs across the F-15 community,” he said. “Cooperative and joint exercises with sister services and other stakeholders can help cross-pollinate ideas and methodologies, strengthen partnerships and increase force effectiveness.”