GKN Aerospace and RTX’s Pratt & Whitney have signed a Technology Development Agreement to additively manufacture a large-scale engine case for the F135, the engine that powers the F-35 Lightning II. Announced at the Farnborough Air Show on 20 July 2026 and backed by the Norwegian Defence Materiel Agency (NDMA), the program targets a first demonstrator component in 2027 and a certified product by the end of 2028.
The work will be led from GKN Aerospace’s site in Kongsberg, Norway, using the company’s laser-directed energy deposition with wire (L-DED-w) process. The partners describe the resulting structure as likely to be among the first of its scale in a military engine application, a claim that rests less on the printing itself than on the size and load path of the part in question.
What the F135 is
The F135 is the sole engine for the F-35 Lightning II, fitted to all three variants, the F-35A, F-35B and F-35C, which share a common airframe and propulsion platform along with maintenance, training and supply chains. Pratt & Whitney delivered the first production engine in 2009. As of 2025, more than 1,300 engines power over 1,100 aircraft for the US Air Force, Marine Corps and US Navy and 20 allied nations, supported through a sustainment network spanning multiple depots, 32 bases and 12 ships. The company puts thrust at more than 40,000 lbs and the fleet total past one million engine flight hours.
That installed base shapes what comes next. Pratt & Whitney says F-35 operators agreed an upgrade was needed to meet future platform demands while holding to the original engine life specifications, and developed the Engine Core Upgrade (ECU) in response, drawing on the Navy’s Fuel Burn Reduction compressor and turbine testing and the Air Force’s Adaptive Engine Transition Program. The ECU is designed to retrofit across all three variants with more than 60% commonality with the current engine, reusing existing production and maintenance infrastructure rather than replacing it.
An interchangeable part, not a redesign
The additive program is bound by the same logic. The 3D printed case must remain compatible and interchangeable with the current F135 design, reproducing every existing interface, which rules out the usual additive dividend of consolidating or reshaping a part and forces the process to hit an existing drawing instead.
GKN Aerospace and Pratt & Whitney frame the assessment around supply chain resilience, shorter lead times, lower material usage and overall production efficiency. The timing is not incidental. Pratt & Whitney is scaling F135 output, the company has said it raised production rates by around 20% and invested over $1 billion in its factories, while carrying the ECU toward a production decision that US government watchdogs have placed no earlier than 2031. Any route that shortens the queue for large forgings has an obvious constituency.
Sébastien Aknouche, Senior Vice President at GKN Aerospace, said the initiative “reflects our ambition to further develop and industrialise additive technologies for demanding aerospace applications.” Chris Johnson, vice president of the F135 Program at Pratt & Whitney, said the partners are exploring “new manufacturing approaches that contribute to future engine readiness.”
Certifying metal AM without touching the design
GKN Aerospace and Pratt & Whitney’s approach treats the F135 case as a test of whether large-scale metal AM can be certified into an existing military platform without changing anything about it. The gap being closed is can a printed version stand in for the forged one without anyone downstream needing to requalify the engine around it.
Norsk Titanium’s structural titanium components for the Boeing 787 followed the same logic years earlier: Boeing designed the parts, and Norsk’s Rapid Plasma Deposition process was qualified to produce them as a second path to the same design, an alternative to forging, not a departure from it. That case became the first time a commercial aircraft flew with certified additive titanium in a structural role.
AML3D’s ARCEMY X systems at Newport News Shipbuilding point the same direction on the defense side: the wire-arc systems are being used for fabrication and replacement of ship components, where the value is a faster, more resilient source for parts that already have a spec, not a redesigned one.
Both cases show the same trade GKN and Pratt & Whitney are making: additive earns its place by disappearing into the existing design instead of changing it. The F135 case, at engine-structural scale, is the sharper version of that same strategy.
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Featured image shows F135 engine cases. Photo via GKN.
