Honeywell Aerospace has launched the P40 Power and Thermal Management System (PTMS) upgrade for the Lockheed Martin F-35, offering a 25% increase in cooling capacity.
The upgrade raises the PTMS’s capacity from about 32kW to 40kW through a combination of software updates and targeted improvements to liquid-cooling subsystems.
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In a 22 September release, Honeywell Aerospace stated that this upgrade does not require modifications to the aircraft airframe and can be carried out in coordination with scheduled maintenance, such as the planned Engine Core Upgrade, reducing operational disruption.
The company confirmed that the P40 upgrade will be ready for integration into F-35 aircraft between 2029 and 2030.
Honeywell Aerospace defence and space president Matt Milas said: “Operators need additional cooling capacity and improved readiness on a timeline that matters. 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 modernisation requirements.”
Honeywell Aerospace described the P40 as a critical step towards meeting both current and future thermal management needs, noting that the upgrade establishes a platform for potential phased expansions that could eventually support capacities beyond 62kW.
The PTMS underpins 14 essential functions on the F-35, including auxiliary and emergency power, engine start, environmental conditioning, and thermal management.
According to Honeywell Aerospace, the deeply embedded nature of the PTMS means that completely replacing it would require extensive aircraft redesign, requalification, and a disruptive transition across the entire fleet.
By expanding the system within its existing architecture, the P40 upgrade reduces such risks and maintains compatibility with in-service aircraft.
The company, together with the original equipment manufacturer, analysed almost one million hours of global F-35 fleet flight data to trace the causes of PTMS-attributable non-resettable in-flight shutdowns.
As a result, corrective adjustments included in the P40 are projected to reduce these events by about 30%, with further reliability improvements planned.
Retaining the current infrastructure also brings logistical advantages. The company stated that by leveraging existing maintenance expertise, repair facilities, and supporting tools across partner nations, the P40 approach avoids the costs and complexity of creating a new global sustainment network.
Fleet operators are expected to benefit from reduced transition challenges and will be able to enhance aircraft performance and operational readiness with minimal disruption.
