1,750th PTMS turbomachine for F-35 fighter jets | Honeywell Aerospace

The F-35 Power and Thermal Management System (PTMS) turbomachine is the only system of its kind in operation, with its performance and reliability proven over more than 1 million flight hours on nearly 1,200 F-35 aircraft delivered to the U.S. and Allied nations. The turbomachine’s innovative technologies enable the PTMS to operate as an auxiliary power unit, emergency power unit, environmental control system, and thermal management system in one highly integrated package.

Honeywell’s established and fully qualified global supply chain continually produces and sustains F-35 PTMS turbomachines, with the 1,750th delivery on track for this month. This robust and resilient supply chain is integral to the global Defense Industrial Base, with PTMS parts manufactured and maintained in the United Kingdom, Canada, Mexico, France, Netherlands, and Czech Republic.

Low-risk, scalable PTMS upgrade

The PTMS is a foundational element of the F-35 program’s global sustainment and industrial participation network. Honeywell understands all 19 international F-35 program partners are looking for a low-risk, scalable PTMS upgrade option that minimizes development, production, retrofit, and sustainment costs for their 1,156 and counting aircraft orders. Honeywell will leverage our existing global industrial base to minimize PTMS upgrade costs and provide a scalable solution to avoid extra costs for cooling capacity that may not be needed by all international partners. 

“Through our internal investments, we’re making great progress on a software-only upgrade to partially increase F135 engine life through reduced bleed air usage while the Engine Core Upgrade is developed and fielded,” said Lori Schneider, Vice President, Defense Original Equipment Manufacturing, Honeywell Aerospace Technologies. “In addition to cutting engine overhaul costs, this low-risk software upgrade will increase cooling capacity 25 percent to 40kW and enable next-generation avionics upgrades by 2029.”

Honeywell is also investing in the hardware upgrades to boost the PTMS’ cooling capacity to 80kW, already successfully demonstrated using F-35 digital twin models. These upgrades are designed to minimize risk and cost by reusing 95 percent of current PTMS hardware, maintaining existing interfaces, and preserving the F-35’s critical functions.

Honeywell’s PTMS is so integral to F-35 aircraft systems that a clean sheet replacement would require a high-risk and massively expensive reintegration and retest program to requalify its 14 mission and safety-critical functions. These include functions that cool and pressurize the cockpit, provide oxygen to the pilot, supply emergency power to primary flight controls if the main engine or generator fails, and supply ram air to cool avionics systems essential for a safe landing during an in-flight emergency.

Proven PTMS for F-35

“Upgrading our proven PTMS is the smart choice for domestic and international taxpayers and warfighters,” said Rich DeGraff, President, Control Systems, Honeywell Aerospace Technologies. “Our low-risk solution builds on more than $100 million in recent investments across military and commercial programs—advancements that are already flying today. That dual-use experience accelerates fielded capability by at least 3 years compared to a clean-sheet design and avoids costly, redundant development. We’re delivering a solution that saves over $7 billion in development, production, retrofit, and sustainment—while minimizing potential disruption to warfighter readiness and the supply base.”

Honeywell’s PTMS is supported by a world-class service network around the globe. Honeywell has partnered with Lockheed Martin, the F-35 Joint Program Office, and international allies to establish PTMS repair capabilities in the European and Asia-Pacific regions. In 2022, Honeywell successfully transferred PTMS turbomachine repair capability to Aeronamic, which is co-located at the Royal Netherlands Air Force (RNLAF) base in Woensdrecht, Netherlands. A modular test cell is on track for delivery to Aeronamic in late 2025 to enable full turbomachine test capability after repairs. In addition, Honeywell is pursuing opportunities in Australia to establish additional repair capabilities for a select group of PTMS components.