(Editor's Note: This story has been updated with a statement from Pratt & Whitney.)
General Electric and the Air Force have completed testing for the company's second Adaptive Engine Transition Program prototype, marking the end of GE's current AETP efforts as the Air Force weighs whether to move forward with the program, the company announced in a press release today.
Called the XA100, the engine is GE’s offer for an upgrade to the Air Force’s F-35A. The engine includes features such as the ability to transition between a fuel-efficient flight mode to a high-thrust combat setting, known as an adaptive engine, and improved thermal management.
"This is the culmination of more than a decade of methodical risk reduction and testing GE has completed with the Air Force across three different adaptive cycle engine programs," GE Edison Works' Vice President and General Manager for Advanced Products David Tweedie said in the release.
"The engine performance data we gathered at AEDC continued to show the XA100's transformational capability, while also demonstrating a return on substantial Air Force and taxpayer investment. We now stand ready to transition to an Engineering and Manufacturing Development program and bring this engine to the field with the F-35 before the end of this decade."
GE received an AETP contract in June 2016 alongside rival engine maker Pratt & Whitney, the manufacturer for the Air Force’s current F135 engine.
The two companies have since been developing AETP prototypes designed to fit into the Air Force’s F-35A, though the F-35 Joint Program Office has also explored the feasibility of a “tri-variant” engine solution that would be viable across the entire F-35 fleet as it considers a business case assessment for propulsion modernization, Inside Defense previously reported.
A new suite of capabilities brought on by the F-35’s Block 4 upgrades will require greater power and cooling than current engines can provide. In response, GE is backing a follow-on engine for the F-35, touting the XA100 as a contender.
Pratt has also developed two AETP prototypes called the XA101, but the company supports an alternative approach that will gradually upgrade the F-35’s existing F135 engine through two Enhanced Engine Packages.
"XA101 testing remains on track and aligned with the U.S. Air Force’s AETP development timeline,” a Pratt spokesman said in a statement to Inside Defense.
"P&W’s block upgrade to the F135, known as the Enhanced Engine Package (EEP), delivers the fastest, most cost efficient, lowest risk path to fully enabled Block 4 capability for all F-35 operators, while saving taxpayers $40 billion in lifecycle costs and building upon a combat-tested architecture with more than one million flight hours of dependable operation," he added.
Air Force officials have yet to determine whether the service will pursue a follow-on engine, though service Secretary Frank Kendall recently indicated officials plan to decide in time for the filing of the fiscal year 2024 budget request.
John Sneden, the Air Force’s propulsion chief, told reporters at the service's Life Cycle Industry days in August that AETP’s future hinges on whether the service pursues a new engine for the F-35.
If the Air Force chooses to upgrade the existing engine, AETP will not transition into the EMD phase, Sneden said.
Regardless of the program’s fate, Sneden said in an interview with Inside Defense that AETP will serve as the “baseline” for the service’s Next Generation Adaptive Propulsion program, which is designing an engine planned to fit in with any future Next Generation Air Dominance platform.