Lockheed eyes two-year timeline to pick new F-35 cooling system

A US Air Force F-35A Lightning II assigned to the F-35A Lightning II Demonstration Team performs a practice aerial demonstration prior to the Warriors Over the Wasatch Air Show at Hill Air Force Base, Utah, on June 28, 2024. (US Air Force photo by First Lieutenant Nathan Poblete)

AFA WARFARE 2025 — Selecting a highly-anticipated upgrade for the F-35’s incumbent cooling system may take as long as two years to play out as manufacturer Lockheed Martin weighs options from Collins Aerospace and Honeywell, according to the company’s program manager.

“There’s a few folks that have already presented some options to us now. That’s going to take us, I think, about the next 24 months or so to really go through those options,” Chauncey McIntosh, Lockheed’s vice president for the F-35 program, told Breaking Defense Monday in an interview on the sidelines of the AFA Warfare Symposium.

Lockheed is examining “all offerings that are out on the market today to make that decision and go through [them]. So it’s not going to be a quick choice, it’s going to be one that’s driven by data” that ensures the company is “getting the right thing” to support future needs, McIntosh added. “So that’s kind of the time frame that I think we’re on, but as we go through, that could either accelerate or decelerate,” based on what the company learns. 

Collins and Honeywell are so far the only companies to have publicly thrown their hat in the ring for a new cooling system. Lockheed will run the competition, Breaking Defense previously reported, setting up a lucrative opportunity for an eventual winner that would provide parts to retrofit likely a bulk of the roughly 1,000 F-35s currently in service and manufacture the system for future aircraft.

Officials say a new cooling system, formally known as the Power and Thermal Management Unit (PTMU), is needed to support forthcoming upgrades that are expected to make the jet run even hotter than it does now. In the near term, an enhancement to the stealth fighter’s Pratt & Whitney F135 engine is expected to enable a suite of upgrades known as Block 4. Beyond Block 4, a new cooling system will be needed to work in tandem with the engine upgrade, the F-35 Joint Program Office has previously said.

Regardless of how a competition for the new cooling system proceeds, time is of the essence. A previous request for information from the JPO said the government expects a new cooling system solution should be ready to field in roughly the 2032 timeframe. According to a May 2024 Government Accountability Office report [PDF], the F-35 program could start delivering post-Block 4 upgrades as soon as 2029. That timeline, the watchdog found, means that “if the thermal management system upgrades come after 2029, post-Block 4 capabilities will also be delayed.”

Remarking on the need to keep various requirements in sync, McIntosh said, “We’re gonna let the data drive us while knowing we’re on a timeline to insert that engine along with the PTMU out in the future.” 

Honeywell supplies the incumbent cooling apparatus, known as the Power and Thermal Management System (PTMS), which is responsible for other critical tasks like providing emergency electrical power — and is offering an upgrade to the existing design. Collins, a subsidiary of RTX, is looking to unseat Honeywell by introducing a new offering dubbed the Enhanced Power and Cooling System (EPACS). 

Both Honeywell and Collins say their candidates meet an objective set out by the JPO: a capacity for 80 kilowatts of cooling. Honeywell touts its approach, which the company’s Defense and Space President Matt Milas shared with Breaking Defense following the results of digital modeling, as less risky, due to the fact that it retains much of the PTMS’s current “footprint” with largely mature technologies.

Collins, on the other hand, is pitching the EPACS as an alternative solution to meet the F-35’s needs, which the system’s chief engineer Matt Pess recently told Breaking Defense is being developed with the goal of “leav[ing] as much margin in the system and as much flexibility in the system as possible.” Breaking Defense also toured the company’s facility and viewed the EPACS prototype in action last year. 

“We looked at the total box of things that we were asked about” and worked to “make sure that we were mission critical itself and make sure that our system would actually hold up to that,” Henry Brooks, Collins president of power and controls, said in a Feb. 27 interview alongside Pess. “I think that our solution will be a novel one, if you will, for the F-35. It’ll enable not only the F-35” but also sixth-generation fighter jets like the Air Force’s Next Generation Air Dominance platform as well as future commercial aircraft designs.

Additionally, according to Collins, the EPACS has achieved Technology Readiness Level 6, meaning the system is mature enough to enter into the engineering and manufacturing and development phase.