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Is the Pentagon Downplaying Design Flaws in the Joint Strike Fighter?

Earlier this month, Bloomberg News reported on a "design flaw" in the wing of the Air Force and Marine Corps variants of the F-35 discovered during testing. The F-35 program office told Bloomberg and at least one other news outlet that the problem is not serious. However, a March briefing slide by the F-35 program office never intended for public release, but obtained by POGO, indicates the solution to the problem was considered "likely to be expensive and time consuming."

Given what the F-35 program office said privately in their briefing slide, did they downplay the problem publicly?

The F-35 program office and prime contractor Lockheed Martin have determined that it will take 45 days to modify each of the 60 joint strike fighters (JSFs) affected. The modifications will begin next year. Read that again: Each plane affected will be out of commission for 45 days starting next year.

It’s not clear what impact these modifications will ultimately have on the behind-schedule and ever-expensive F-35 program, currently estimated to cost a total of $382 billion for development and production over more than a decade. “It remains to be seen, after the program completes the modification plan, how much disruption could occur to flight test plans in the future due to these modifications,” a Pentagon spokesman told in an email POGO in response to queries sent to the Pentagon’s Director of Operational Test and Evaluation.

Similarly, the Pentagon spokeswoman said, “Until the modification plan is completed by the program office, we cannot be sure what impact the necessary downtime will have on training” on the F-35. She said in the near term there are no anticipated impacts to testing or training. The JSF program office told POGO that the second batch of low rate initial production F-35s—which include affected F-35s that require modification—delivered to Eglin Air Force Base for training purposes have not received flight clearance for unmonitored flight.

But what is certain is that this problem would be a much bigger headache if the F-35 program wasn’t restructured in the last few years to have less concurrency, i.e. producing relatively large numbers of aircraft before development and testing are largely complete. If the F-35 production hadn’t been slowed down, it’s likely far more than 60 aircraft would need significant modifications.

“Problems like this were built into the JSF program from the get go,” said former Senate staffer Winslow Wheeler of the non-profit Center for Defense Information in an email to POGO.

“That is to say, the moment they came up with the incredibly stupid idea to build a supersonic STOVL [short take-off and vertical landing] airplane and to require the Navy and Air Force to have the same basic airframe, they built in the potential for these kinds of structural problems," Wheeler said. "Then when they designed the highly concurrent development/production plan, which remains, they guaranteed that when discovered, these problems are discovered late and at meaningful expense.”

He said that Lockheed’s “efforts to downplay this problem are good practice for them as they will be repeating themselves on these and other issues for years to come.”


Last November, defects in an aluminum beam called a “forward root rib” in the A and B models of the F-35 were detected in test aircraft. This has led to a reduction in the expected life of the F-35A and B wing from 8,000 hours to 1,500 hours, according to Pentagon test office statements to Bloomberg. About 60 A and B models are affected and modifications of them will begin in 2012, F-35 program office spokesman Joseph DellaVedova told POGO in an email. The first of these JSFs to be modified will be durability test planes, he said.

DellaVedova said that "the program has developed a new Forward Root Rib design for incorporation into the CTOL [conventional take-off and landing] and STOVL variants during production from the beginning of Low Rate Initial Production Lot 5." Therefore, new JSFs built from now on should not have a forward root rib problem; only the 60 A and B models that currently exist will require the modifications.

The program office and Lockheed jointly conducted maintenance task analysis to reach the 45-day estimate, DellaVedova emailed.

What Does It Take to be "Serious"?

Bloomberg’s Tony Capaccio quoted DellaVedova earlier this month as saying that “this is not considered a serious issue.” Lockheed Martin spokeswoman Laurie Quincy told Capaccio the F-35 program office statement speaks for the company. (I have included the full official F-35 program office statement that DelleVedova provided at the bottom of this blog post.)

DellaVedova told POGO in an email that the quote of him saying the root rib problem is "not considered serious" in the Bloomberg story and “may have been taken out of context or incorrect.”

When POGO asked whether the program office considered the problem “serious” and pointed out that there was a similar quote in an AOL Defense story on the same issue (which quoted an email saying the problem is “not a serious issue”), DelleVedova emailed:

The fact that we predicted this and that there is a solution/path forward on this issue should provide a gauge. [The] Root rib [problem] didn't halt the flight test program and the Lockheed plant continued to produce jets.

But a PowerPoint slide by the F-35 program office from March of this year suggests the problem might have been considered more serious earlier this year than how it has been portrayed in the press.

The F-35 program office wrote in a briefing slide that this part failure will require a “complex” retrofit that is “likely to be expensive and time consuming.” The “new segment splice requires numerous cuts, fittings, angles, systems R&I and ‘plying’ up the upper wing skin.”

DellaVedova said, "What was leaked/given to you was a moment—a snapshot in time. It does not make what was said then or now wrong or right. Keep perspective."

Lockheed’s Quincy told AOL Defense’s Colin Clark that the fix "will not require additional funding for the F-35 program. The funding to be used is actually part of the concurrency costs that were already reported to Congress by the F-35 Joint Program Office earlier this year.” Clark, commenting on Quincy’s statement, wrote, “So the fix did cost new money but it's old new money.”

To be clear, testing is intended to lead to the discovery of design flaws before full-scale production, so the discovery of problems should not in itself be shocking and is the way the system is supposed to work. However, the cost to fix the design and retrofit JSF planes already produced ultimately adds to the cost of the estimated $382 billion JSF program. And if it turns out more retrofitting is needed than previously thought, costs will rise more than currently estimated and more delays will occur. The growing cost and delays in the JSF program are one of the main reasons budget cutters have targeted the program for potential cuts.

But it is possible that the time it takes to modify 60 JSFs could set the testing efforts back farther than they already are.

F-35 Joint Strike Fighter Program Office statement:

Resolving durability test article findings is a well understood process. Durability testing is conducted early in the development of any new aircraft to avoid costly sustainment issues later in the life of the aircraft. Problems are found and corrected in development rather than fleet service.

The JSF Program has established clear criteria for the Durability and Damage Tolerance of the F-35 Air Vehicle. As part of the preparation for full scale durability testing, Government and Contractor Engineering Teams performed an analytical assessment of the airframes fatigue life. During this analysis, a shortfall in the predicted durability life of the Conventional Take Off and Landing (CTOL) and Short Take Off and Vertical Landing (STOVL) Wing Forward Root Rib was identified. The Root Rib is an aluminum part located where the Leading Edge of the Wing meets the Fuselage. The F-35 has a requirement to achieve 8000 flight hours verified through analysis and test to 2 lifetimes or 16000 total hours. The CTOL durability test, being performed by BAE at Brough, UK recently completed more than 2800 hours when the anticipated crack in the Forward Root Rib was identified. The crack is consistent with analytical predictions both in terms of location and life. The Program in conjunction with the USAF had earlier decided, on the basis of available analytical results, to continue testing in the presence of this durability deficiency and gather further data that could be used to manage the fleet in the most efficient manner.

To correct the durability deficiencies with this part, the JSF Program is executing well-understood engineering and corrective action processes. The Joint Program Office and Lockheed Martin Engineering Teams have already developed retrofit plans and a redesigned full-life Forward Root Rib for both variants. In the interim, fleet and test aircraft continue to be inspected with a simple, non invasive inspection as a precaution ahead of eventual modification. The new Forward Root Rib design will be incorporated from the beginning of LRIP5 for both CTOL and STOVL aircraft (AF31/BF35). 30 CTOL and 34 STOVL LRIP aircraft will require modification to achieve their full design life. The Forward Root Rib modification has been grouped with existing modification requirements to reduce both the cost of the modification and the time aircraft spend in deeper level maintenance. It is expected that the Forward Root Rib modification will require approximately 45 days to complete.