L3Harris Technologies has delivered more than 1,000 shipsets each of the Panoramic Cockpit Display Electronic Unit (PCD-EU) and the Aircraft Memory System (AMS), two of the three core avionics components of the F-35 Lightning II’s Technology Refresh 3 (TR-3) hardware baseline, the company announced on October 19, 2026. Deliveries of both units began in 2022.
The milestone highlights the gap that has defined TR-3 for three years: the hardware is in production at scale, while the software that exploits it is not yet cleared for combat. TR-3, the computing foundation for the F-35’s Block 4 modernization, was originally due in April 2023. Software instability led the Pentagon to stop accepting TR-3 jets from July 2023 to July 2024, and aircraft delivered since then fly with a truncated software load limited to training and combat training. The Director, Operational Test and Evaluation (DOT&E) reported that no combat-capable TR-3 aircraft had been delivered to US services as of the end of September 2025.
Inside the F-35 TR-3 Hardware: PCD-EU, AMS, and ICP
L3Harris builds all three core TR-3 avionics elements. The Integrated Core Processor (ICP), the central mission computer hosting the aircraft’s sensor fusion and mission software, reached full-rate production in 2025. The PCD-EU is the processing unit behind the cockpit’s panoramic touchscreen display, while the AMS provides onboard storage for mission and sensor data. Each replaces a corresponding Technology Refresh 2 (TR-2) component, the configuration still fielded across nearly the entire F-35 fleet.
According to L3Harris, the TR-3 suite delivers a 37-fold increase in processing capability and 20 times the data storage of the legacy system. That headroom is the purpose of the program. Block 4 is built around the AN/APG-85 active electronically scanned array radar, an expanded electronic warfare suite, new weapons and improved sensor fusion, none of which the TR-2 computers can host. DOT&E has noted that a new electromagnetic warfare capability depends on upgraded hardware installed on TR-3 aircraft starting with production Lot 19.
The 1,000 figure applies to each system individually. L3Harris says its production tempo supports both new-build aircraft and upgrades to the fielded fleet, but it did not break the total down between the two. For scale, DOT&E counted 158 F-35s delivered in the TR-3 configuration through September 2025, and Lockheed Martin delivered a record 191 F-35s across all configurations in 2025, after 98 in 2023 and 110 in 2024. The September 29, 2025 award for Lots 18 and 19, valued at $24.29 billion for 296 aircraft, sustains new-build demand for TR-3 hardware, with first deliveries from those lots scheduled for 2026.
TR-3 Field Reliability and the Pending Combat Certification
L3Harris states that its processing hardware has shown reliability exceeding program expectations across an F-35 fleet that has passed 1 million flight hours. The company did not publish supporting data such as mean time between failures or unscheduled removal rates, and the fleet-wide hour total is dominated by TR-2 aircraft.
“In the demanding environments the F-35 operates in, reliability isn’t optional,” said Eric DiStasi, president of Airborne Solutions at L3Harris. Describing the ramp-up, he said the company built the processing infrastructure and “scaled it to full production at speed with the quality to match.”
Government reviews locate the TR-3 bottleneck elsewhere. In its September 2025 report, the Government Accountability Office (GAO) said program officials no longer considered the new core processor a cause of TR-3 delays and identified the new aperture system as the key driver of postponed TR-3-enabled capability. The same report put Block 4 more than $6 billion over budget and found that a reduced set of Block 4 capabilities would not be complete until 2031, five years later than originally planned. DOT&E found that TR-3 software builds remained unsuitable for dedicated operational testing in fiscal 2025.
Under the 2024 acceptance agreement, the F-35 Joint Program Office (JPO) withholds approximately $5 million per TR-3 aircraft from Lockheed Martin until combat capability is qualified and delivered. Lockheed told auditors it planned to begin delivering combat-capable TR-3 aircraft in 2026. Neither the JPO nor Lockheed Martin had publicly confirmed TR-3 combat certification as of October 19, 2026.
Analysis: The milestone confirms that the TR-3 supply chain is not what is holding back F-35 modernization. At 1,000 sets per system, L3Harris has produced display and memory hardware well beyond the number of TR-3 aircraft handed over to customers, a gap that likely reflects fielded-fleet upgrades, spares and inventory for future lots, though the company has not specified the split. That reverses the usual acquisition risk. The US services and partner air forces are accumulating Block 4-ready hardware ahead of the software, sensors and operational testing needed to turn it into combat capability, and each month of delay keeps that investment confined to training roles.
The next decision points sit with the government rather than the supplier: JPO certification of TR-3 combat capability, the start of dedicated TR-3 operational testing, delivery of the next-generation Distributed Aperture System, and the first Block 4 capability releases. On the industrial side, Lot 18 and 19 deliveries will keep PCD-EU, AMS and ICP output at full rate. How many of the 1,000 shipsets are destined for the fielded fleet remains undisclosed, and that figure will show how far the upgrade effort has progressed.