GE Aerospace and Pratt & Whitney have both cleared Assembly Readiness Reviews (ARR) for their competing adaptive cycle engines under the US Air Force’s Next Generation Adaptive Propulsion (NGAP) program, with the two milestones announced within three days of each other.
Pratt & Whitney was first to announce, on May 8, 2026, that it had cleared the ARR for its XA103 design. GE Aerospace followed on May 11, 2026, with the same milestone for its XA102. Both engines are competing to power the Boeing F-47, the sixth-generation fighter at the heart of the Next Generation Air Dominance (NGAD) initiative awarded to Boeing in March 2025 as the eventual successor to the Lockheed Martin F-22 Raptor.
Digital-first development
The ARR is designed to validate that each engine’s design, manufacturing processes, and supply chain are mature enough to begin building a full-scale demonstrator. Both companies said the milestone keeps their respective programs on schedule for the next contract phase. Pratt & Whitney said it expects to finish assembling an XA103 prototype in the late 2020s, with ground testing to follow shortly afterwards. GE Aerospace said it expects the Air Force to award the next phase later this year.
The two manufacturers stated that each review made extensive use of fully digital engine models, with each company highlighting a model-based definition approach connecting design, manufacturing, and inspection within a single digital framework.
The ARR milestone follows the Detailed Design Reviews completed by both contractors in early 2025, backed by a $3.5 billion contract award from the US Department of Defense to fund prototype development through both competitors.
The US Air Force has requested $514 million for NGAP in its fiscal 2027 budget, roughly $187 million more than the previous year, explicitly to maintain competitive prototyping.
