Lockheed Martin’s F-35 Lightning II program is being rocked by soaring costs, delays in the TR-3 upgrade, and engine failures.
Summary
The F-35 program, which is central to the NATO allies’ air strategy, is going through a difficult phase. Estimates of additional maintenance costs over the lifetime of the program now exceed $1.6 trillion (more than €1.5 trillion). The central element of the modernization, the TR-3 (or Block 4) upgrade, is several years behind schedule and at least $6 billion over budget. On the industrial side, the target production rate (approximately 156 jets per year) remains uncertain, as do on-time deliveries. Finally, several allies—notably the United Kingdom—have reported software and logistical problems, which are affecting operational availability. These technical, industrial, and strategic issues raise questions about the program’s sustainability over the coming decades.
Skyrocketing costs: when the bill keeps climbing
The F-35 program was initially announced with relatively modest estimates, but these have been revised upward several times. According to a report by the Government Accountability Office (GAO) published in April 2024, sustainment costs for the entire life of the program have increased by 44% since 2018, from $1.1 trillion to approximately $1.58 trillion. Adding acquisition costs (approximately $442 billion), the total now exceeds $2 trillion.
This decline in efficiency translates into an estimated annual operating cost of approximately $6.6 million per aircraft for the F-35A variant, well above the initial target of $4.1 million.
The conclusion is clear: the logic of a “single” fighter for multiple armed forces, synonymous with cost reduction, is being undermined. The program is absorbing colossal resources, even as other priorities emerge (drones, hypersonic systems). The economic aspect is no longer a minor variable in this project but a critical issue.
The TR-3 (Block 4) upgrade: a modernization that has lost momentum
One of the pillars of the F-35 strategy is to upgrade the aircraft to respond to the threats of the coming decade: new radars, data processing, electronic warfare. This is the purpose of the “Technology Refresh 3” (TR-3) upgrade included in the Block 4 modernization program. However, this phase is experiencing significant delays. According to specialist sources, TR-3 is at least five years behind schedule and has cost overruns of more than $6 billion.
More specifically, flight testing with certain TR-3 components began in 2023, but software instabilities and component quality issues forced the Pentagon to suspend acceptance of the aircraft.
In July 2025, the Joint Program Office (JPO) announced that delivery of the “40R02” version (software) would not be possible before 2026 or later. The scope of the upgrade was reduced to meet a more realistic schedule.
The direct consequence is that aircraft are being delivered with “restricted” capabilities that are not yet fully operational. This calls into question the idea that the F-35 will be able to remain at the cutting edge of technology without undergoing costly mid-life retrofits.
Engine and maintenance issues: reliability under pressure
In addition to software delays, the reliability of the engine, cooling systems, and thermal management is problematic. One report indicates that the current thermal management system is overloaded, reducing the aircraft’s engine life. Replacing or upgrading the engine (EPM program – engine performance modification) is therefore critical but still unstable.
Furthermore, another GAO report highlights that the three variants of the F-35 do not meet mission capability rate targets: operational availability is progressing with difficulty.
In terms of logistics, the spare parts chain is under heavy demand, and the need for heavy maintenance operations is seen as a hindrance to operational deployment. The hourly maintenance cost (cost per flight hour) remains high.
In summary, the aircraft is still struggling to deliver on its promises in terms of reliability and operating costs, which poses a significant risk to its long-term credibility.
Production and deliveries: volume still uncertain
The F-35 program is based on very high volumes: estimates suggest a production rate of 156 aircraft per year in the coming years. However, this does not necessarily correspond to actual deliveries to the armed forces. According to one article, this volume is described as the “intelligent maximum” but is not guaranteed.
For example, in 2023, only 98 aircraft were delivered. In 2024, despite efforts, the average delay for each delivery reached 238 days.
Lockheed Martin is aiming for between 170 and 190 deliveries in 2025, thanks to the addition of aircraft held in reserve.
This distinction between production and delivery is important: the ability to produce does not equate to the ability to deliver on time and with all features. Maintaining such a volume in a context of increased complexity (modernization, global supply chain) is a major industrial challenge.
Availability of allied forces: warning signs are multiplying
The program’s allies are expressing reservations about their own fleets. In the United Kingdom, the House of Commons has highlighted delays in upgrades, parts issues, and lower-than-targeted effective operation rates. Reports suggest that the British fleet may only be able to fulfill about one-third of its planned missions due to material and logistical support constraints.
Israel, the first user of the F-35 in “real” conditions, has also reported software bugs affecting internal systems and interoperability, fueling concern among other partners. Although less publicly documented, this confirms that the aircraft is still in a maturation phase.
For user countries, this context creates tension: acquiring a so-called “fifth-generation” aircraft means betting on future capabilities that are not yet fully operational, while bearing significant operating costs and upgrade delays.
Strategic and industrial impacts: towards a readjustment of the model
The F-35 was envisaged as a long-term palliative in the face of the proliferation of advanced air defenses and upgraded fourth-generation aircraft. But several facts call this model into question.
On the one hand, rising operating costs are limiting profit margins: each hour of flight is becoming more expensive. On the other hand, delays in modernization and reduced availability call into question the F-35’s ability to maintain its technological advantage. This could push countries to anticipate the next generation of combat aircraft or to diversify their solutions (drones, long-range missiles, stronger international cooperation).
On the industrial side, the challenge is twofold: maintaining a high-volume production line while integrating increasingly complex technologies (AESA radars, electronic warfare, embedded AI). Add to this the pressure on engines, global logistics, and maintenance requirements, and we see a cost model that could evolve toward “lean” or modular production rather than mass production.
Finally, on a strategic level, the commitment of allies to the F-35 remains a key anchor. But the cost, delays, and ongoing maintenance are turning this anchor into a credibility issue: that of being able to deploy an aircraft that meets expectations at a time when air threats are rapidly evolving.
Towards an adjustment of the program: what are the options for the future?
Three main approaches are emerging:
- Reducing the scope of modernization: the decision to deliver aircraft with “intermediate” capabilities (not including all TR-3 elements) shows that the program is moving towards a graduated model. This avoids blocking all deliveries for a single unfinished block.
- Optimization of logistics and maintenance: to contain costs, reducing the cost per flight hour, improving parts availability, training, and predictive maintenance are at the heart of the strategy. The GAO report highlights that many of the recommendations (43) have not yet been implemented.
- Diversification of air capability approaches: Some countries are beginning to combine 5th generation aircraft with drones or modernized 4+ generation aircraft. The F-35 can no longer be the sole pillar, regardless of its cost and temporary limitations.
The F-35 program remains a strategic asset for its operators, but it is now entering a phase of recalibration where ambitions must be reconciled with industrial and operational realities. For allies, it will be necessary not only to acquire the aircraft, but also to ensure that it is available, maintainable, and adaptable in a world where air and electronic threats continue to grow. The coming months will be crucial in assessing whether this program can deliver on its promises or whether it must embark on a new path of evolution.
Sources:
Government Accountability Office; Defense Industry; Defense News; Bloomberg; Congress Research Service; Breaking Defense.
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