Honeywell Aerospace advances F-35 cooling capacity with 40-kilowatt upgrade

PHOENIX, Sep. 22, 2026 — Honeywell Aerospace (Nasdaq: HONA) has launched its 40-kilowatt Power and Thermal Management System (PTMS) upgrade, a low-risk solution that increases F-35 cooling capacity by 25%, improves reliability and provides a scalable path to meet future cooling demands.

As the F-35 adds increasingly capable sensors, mission systems and processing power, demand for cooling continues to grow. Honeywell Aerospace’s “P40” upgrade increases cooling capacity from approximately 32 kilowatts to 40 kilowatts through software updates and targeted liquid-cooling enhancements. It requires no airframe modifications and can be incorporated alongside the aircraft's planned Engine Core Upgrade, allowing operators to add cooling capacity during an already scheduled maintenance event.

“Operators need additional cooling capacity and improved readiness on a timeline that matters,” said Matt Milas, president of Defense and Space at Honeywell Aerospace. “P40 delivers both by building on the proven PTMS architecture already operating across the global F-35 fleet. It provides meaningful near-term cooling growth while preserving a scalable path to support future modernization requirements.”

Honeywell Aerospace expects to field this technology between 2029 and 2030, providing operators additional thermal capacity years before a replacement architecture could be developed, qualified and fielded. The upgrade also establishes a foundation for future thermal growth, enabling a phased modernization approach that expands capability while preserving investments already made across the F-35 enterprise.

Building on more than 1 million flight hours

Honeywell Aerospace's PTMS performs 14 mission- and safety-critical functions, including auxiliary power, emergency power, engine starting, environmental control and thermal management. The system has accumulated more than 1 million flight hours across the global F-35 fleet.

Because the PTMS is deeply integrated across the aircraft, replacing it would require extensive redesign, qualification, airframe integration and fleetwide transition activities. P40 instead expands cooling capacity within the existing architecture, reducing technical, certification and schedule risk while maintaining compatibility with aircraft already in service.

Reliability improvements

Beyond increasing cooling capacity, P40 is expected to improve system reliability.

After analyzing nearly 1 million fleet flight hours, Honeywell Aerospace and the OEM identified the root causes of Honeywell-attributable non-resettable in-flight shutdowns. The resulting corrective actions, implemented in P40, are projected to lower the occurrence of these events by about 30%.

Additional reliability initiatives are expected to further improve system performance and reduce maintenance burdens across the fleet.

Preserving global sustainment investments

The P40 approach preserves the repair, sustainment and support infrastructure already established across the F-35 enterprise, including qualified maintenance facilities, tooling and technical expertise developed by partner nations.

By leveraging the existing architecture, operators can expand cooling capacity without creating a new sustainment network, reducing transition costs and operational disruption.

A practical path forward

As cooling demands continue to grow, P40 provides a scalable modernization path that can ultimately expand system capacity to 62 kilowatts and beyond. The approach allows operators to increase cooling capacity in phased increments while preserving fleet commonality and avoiding the cost, schedule and integration challenges associated with replacing a deeply embedded aircraft system.