It Takes 41,500 Hours Of Labor To Build A Single F-35A According To New Report

The first of the UK’s F-35Bs arrived at RAF Marham today to much fanfare. It was a big, long-awaited milestone not only for the Royal Navy and Royal Air Force, but also for the F-35 program. Meanwhile the U.S. Government Accountability Office, better known as the GAO, has released a new report on the status of the F-35 program overall. One of the most interesting tidbits in the report was metrics on how many man hours of labor it takes to manufacture each type of F-35 and how those numbers have changed over time.

The chart below shows exactly how many labor hours are poured into constructing each F-35 variant on average. With the A model unsurprisingly being the lowest at 41,541 hours in 2017, the more complex B model taking 57,152 hours, and the carrier-capable C model coming in at 60,121 hours. 


These numbers generally vibe with the differential in cost of each type as well. But what’s most intriguing is just how much these metrics have decreased over time, underlining that Lockheed has found meaningful efficiencies on the F-35 production line in recent years.

Over a five year period of time, the labor it took to assemble a single F-35A dropped by a whopping 62 percent. This is skewed somewhat due to the number of airframes ordered in 2012 compared to 2017, but the between 2016 and 2017 alone the same metric dropped an impressive 12 percent. This is a considerable change for just one year and tells an important story when it comes to the maturity of the F-35’s design compared to 2012.

The GAO report states:

These improvements in airframe manufacturing efficiency indicate that manufacturing processes are stabilizing and coming under control, and production capability is improving. Lockheed Martin has delivered a total of 266 aircraft to DOD and international partners. As of January 2018, 170 aircraft were in production worldwide, an increase of 20 percent from January 2017. As Lockheed Martin gained more production experience, the average hours needed to produce an aircraft decreased, as shown in figure 6. The line of best fit, shown below, is calculated to help visualize a trend in the rate of change in the data.


The average hours needed for rework and repair of aircraft already delivered is still a major issue, but it is also receding, with a change of 70 percent between 2012 and 2017, and 20 percent between 2016 and 2017. Once again, it’s still taking a whopping 6,237 hours of labor to correct production mistakes on each brand new jet. In many cases, this means those aircraft are being pulled from the fleet to receive corrective measures, and at great cost, but at least that number seems to be heading somewhat in the right direction.

The F-35 assembly line in Fort Worth, Texas. , Lockheed Martin

The report described the drop as a good thing, but it notes that it doesn’t take into account another looming issue that could drastically impact these metrics:

According to Lockheed Martin, the rate of quality defects discovered per aircraft delivered has declined 21 percent from 2016 to 2017. However, this metric will likely be affected next year due to a recent discovery of a fault in the production process. Specifically, according to Defense Contract Management Agency officials, in September 2017 Lockheed Martin halted deliveries of aircraft after the Air Force identified corrosion between the aircraft’s surface panels and the airframe because Lockheed Martin did not apply primer when the panels were attached. According to the program office, the Defense Contract Management Agency, Lockheed Martin, and program office subject matter experts are investigating the impact on aircraft that have been delivered without the primer, and estimate that repairs may take between 30 to 40 days per aircraft at a cost that is yet to be determined. More than 270 aircraft have been identified as lacking the necessary primer as of February 2018. According to the program office, responsibility for the costs associated with this issue has not been negotiated. Meanwhile, delivery of aircraft resumed in October 2017.

All three F-35 variants fly together in formation near Eglin AFB in Florida. , USAF

The F-35 has been flying for over 11 years and has been a constant source of delays and weakening requirements, but these figures do indicate a design whose production process is finally maturing. This reality is also reflected in unit price declines, which is a good thing. Yet at the same time, it also underscores just how ridiculously far-fetched Lockheed’s original timelines and fiscal goals were for the program. 

As far as the question of how the F-35’s labor hours for production compares to other aircraft, we are having a tough time answering it definitively at this time, at least with fresh data. But according to an archived POGO report, an F-16A took 29,000 man hours to produce in 1984, and the more complex and relatively new F-16C took 45,000 man hours to build in 1989. That same source noted that just the F-22’s center fuselage section took 60,000 man hours to assemble when the program was in its pre-production state in the late 1990s. This was mainly due to the 60,000 fasteners that were used on the section, each of which was installed by hand taking roughly 30 minutes to an hour. 

The F-16 production line in Fort Worth, Texas. It is now being moved to South Carolina. , Paul Chesley-Getty Images

So with just these metrics in hand, the F-35 program doesn’t seem to be gobbling up labor at an astronomical rate, especially considering its low-observable design, which are historically very expensive to produce. The fact of the matter is that all aircraft take a lot of time to build. Even during World War II, when the fate of Britain hung in the balance, it took a whopping 13,000 man hours to build a single Spitfire Mk V. In contrast, it took the Germans 4,000 hours to build a Me109G. 

We found the chart below in the forums at and we can’t confirm its accuracy, but it seems to be a good comparative snapshot of the time it took to build other WWII aircraft. You will notice the massive delta in efficiency just over a single war year for all the types stated:

B-24 Liberator assembly line., USAF

The real question is how many man hours does it take to produce a competing modern fighter, in particular, the F/A-18 Super Hornet. We reached out to Boeing this morning for that data, but have yet to hear back. We will update the post if and when we get those numbers. 

But the GAO report is not all good news. The F-35 still has a massive number of unresolved issues that have no sign of being fixed before the decision to enter into full-rate production is made. 

The report states:

  1. To complete the F-35 development program without further delays, the program office plans to defer resolving—to fix or have an approved work around—a portion of the known deficiencies to post-development efforts. During testing, issues identified with the aircraft’s performance are reported to the program office as deficiencies, which are then categorized based on how severely the deficiency impacts the aircraft’s performance.
    • Category 1 deficiencies are those that could jeopardize safety, security, or another critical requirement.
    • Category 2 deficiencies are those that could impede or constrain successful mission accomplishment.


According to program office officials, in early 2017 the program office determined that not all open deficiencies found in developmental testing could be resolved within the cost and schedule of the development contract. As a result, the program office and the military services reviewed all open deficiencies and determined that about 30 percent of them needed to be resolved before completing development. According to program officials, some of the remaining deficiencies will be resolved through post-development contracts and not on the baseline development contract.

While the program office’s plans for resolving deficiencies remain in flux, officials told us that some are expected to be resolved on future contracts and not through the existing development contract. DOD officials have stated that the program will hold a summit later this year to determine who will be responsible for the costs associated with resolving the remaining deficiencies.

As of January 2018, the F-35 program had 966 open deficiencies—111 category 1 and 855 category 2. At least 25 category 1 deficiencies and 165 category 2 deficiencies will not be resolved before full-rate production. See table 2 for a breakdown of deferred category 1 deficiencies by the system affected. 

According to program officials, it is time to complete the development program as all capabilities have met threshold requirements and are on track to be delivered. Therefore, they told us that it is reasonable to continue resolving deficiencies while in production. The program officials stated that the proposed approach for resolving deficiencies is still under consideration and has not been approved.

DOD’s acquisition instruction, however, states that critical deficiencies identified in testing are to be resolved before proceeding beyond low-rate initial production or limited deployment, except as specifically approved by the program’s milestone decision authority. This policy states that identifying and correcting deficiencies early is less costly than resolving deficiencies later in the acquisition process.


The report went on to discuss a variety of other issues and topics, including the pitfalls of the F-35’s proposed Block 4 enhancements, as well as the fact that the F-35 has seen little to no improvement in its fairly dismal reliability and maintainability and that it will likely miss a number of threshold requirements relating to those issues before the decision to enter into full-rate production is made. 

In the end the GAO recommended the following:

Direct the F-35 program office to resolve all critical deficiencies before making a full-rate production decision.

Direct the F-35 program office to identify what steps are needed to ensure the F-35 meets reliability and maintainability requirements before each variant reaches maturity and update the Reliability and Maintainability Improvement Program with these steps.

Whether the Pentagon will end up actually keeping the F-35 in ‘purgatory’ low-rate initial production status until its bevy of critical issues is fixed, we will have to wait and see, especially considering the White House has had a heavy sway over the program since President Trump took office 501 days ago. 

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