General Electric [GE] said on Sept. 12 that it has tested out the company’s second XA100 adaptive cycle engine at the U.S. Air Force’s Arnold Engineering Development Complex in Tullahoma, Tenn., for the Air Force’s Adaptive Engine Transition Program (AETP).

The completion of the testing of the second XA100 comes a year after such testing on that engine began in August last year, per the company.

“With testing at AEDC completed, GE has accomplished the final major contract milestone” of AETP, GE said.

David Tweedie, GE Edison Works’ vice president and general manager for advanced products, said in a Sept. 12 statement that GE is ready to begin an AETP Engineering and Manufacturing Development phase for the XA100 to field the engine before 2030.

The Air Force is pursuing AETP and the Next Generation Adaptive Propulsion (NGAP) program for the service’s Next Generation Air Dominance (NGAD) fighter program.

Five companies–General Electric, Raytheon Technologies

‘ Pratt & Whitney [RTX], Boeing [BA], Lockheed Martin [LMT], and Northrop Grumman [NOC]–are receiving contracts under an umbrella, $975 million effort for the prototype phase of the NGAP program (Defense Daily, Aug. 19).

In fiscal 2023, the Air Force requested nearly $354 million for advanced engine development, including $286 million for AETP and nearly $68 million for NGAP. Senate defense authorizers and appropriators agreed to the Air Force request. House defense authorizers recommended boosting AETP by $150 million in fiscal 2023, while House appropriators said that they advised funding the Air Force’s nearly $354 million advanced engine development request but, “at the Air Force’s request,” decreasing AETP funding to $133 million and increasing NGAP to $220 million.

The Pentagon is also considering AETP as an option for the Lockheed Martin F-35 fighter and is likely to lay out a path forward for a future F-35 engine in next year’s fiscal 2024 budget request.

Since 2016, the Air Force has funded the AETP, but thus far it appears that an AETP engine will fit on the F-35A and possibly the Navy F-35C, not on the Marine Corps’ F-35B short takeoff and vertical landing variant, as the latter requires an engine that drives the lift-fan system, provides bleed air to the roll-posts, and uses a swivel exhaust duct.

GE’s Tweedie on Sept. 12 said that the XA100 “isn’t a concept, proposal, or research program.”

“This is a flight-weight, highly product-relevant engine that would provide the F-35 with 30 percent more range, greater than 20% faster acceleration, and significant mission systems growth to harness the F-35’s full capabilities for Block 4 upgrades, and beyond,” per Tweedie’s statement. “The XA100 is the only F-35 propulsion modernization option that has been built, fully tested, and evaluated against Air Force performance targets, and the only option that provides the Air Force the capability it needs to outpace its adversaries for decades to come.”

Pratt & Whitney, which builds the F-35’s current F135 engine, has said that its F135 Enhanced Engine Package (EEP) has “ample design margin” to allow for the envisioned Block 4 upgrades for the fighter and that EEP will save $40 billion in lifecycle costs.

AETP would involve an estimated $6.7 billion for the development of a new power plant for the F-35 (Defense Daily, June 30).

In June 2016, General Electric and Pratt & Whitney received AETP contracts worth more than $1 billion each. “Since delivering the first [F135] production engine in 2009, P&W has invested more than half a billion dollars in capital, process improvements and cost reduction initiatives to support the production ramp and reduce the average unit cost of the F135 by more than 50 percent,” Pratt & Whitney has said.