AFA WINTER, ORLANDO: Some 9,400 hours of ground testing of the F-35B exposed serious cracks in the plane’s aluminum bulkheads, sending the Joint Strike Fighter program and contractor Lockheed Martin scrambling to come up with long-term engineering solutions.

The Marines say any correction will be made later to their aircraft and will not slow initial fielding of the most complex version of the Joint Strike Fighter.

“The bulkhead crack was found in the ground test vehicle during durability testing after more than 9,400 hours,” Capt. Richard Ulsh, aviation spokesman for the Marines, said in an email. “This event does not impact the IOC date of the F-35B, which the Marine Corps still plans to achieve in July 2015. This finding only affects the future modification schedules to our aircraft so they can achieve the intended service life of the aircraft, which is 8,000 hours.”

Ulsh noted that the goal of durability testing is to stress “the aircraft to its structural limits so that issues and corrective actions can be identified. These discoveries are expected and planned for in a developmental program.”

Ground testing was halted after the extent of the cracks became clear because the test had accomplished its goal of finding out what happens to the aircraft when stressed beyond its expected lifetime, a program source said.

The cockpit bulkheads of the F-35A and C, the Air Force and Navy versions, are built of titanium. The program source said they were not likely to use titanium for the Marine fixes, but are more likely to come up with a combination of maintenance and structural reinforcements to manage the cracks over the aircraft’s expected life. Given the history of America’s military aircraft, the F-35B is likely to be in the air for a very long time and may substantially exceed that 9,480 hours.

The greatest challenge for the engineers is posed by the thin remaining weight margins for the complex plane, which can land vertically and take off in a very short space.

The annual Operational Test and Evaluation report says only 202 pounds remains to work with, a tiny margin. Frank Kendall, head of Pentagon acquisition, told colleague Tony Capaccio that the cracks problem is “significant but by no means catastrophic.”

The program office said in s statement that the bulkhead repairs are expected to begin in March. Once they figure out the combination of maintenance and engineering to deal with this issue, they will restart ground testing around September. 


  • CharleyA

    It will be interesting to so how much these cracks add to concurrency costs for the Bravo, and at what production lot the fixes are incorporated.

  • Harold

    Thanks for the news. In the meantime here you can take a look at some great F-35 photos:

    F-35 Joint Strike Fighter Pictures

  • Harold

    Thanks for the news. In the meantime here you can take a look at some great F-35 photos:

    F-35 Joint Strike Fighter Pictures

  • Don Bacon

    There is a long history of aluminum bulkhead cracking during F-35B durability testing beginning in 2010, when it caused a 16-month break in durability testing, restarting in January 2012. The recent 2013 DOT&E report stated:

    Further testing was halted in September when cracks were discovered in two of the bulkheads, requiring repair.

    Now it’s three bulkheads.
    Image F-35B wing carry-through bulkhead here.

    • Don Bacon

      Here’s a pdf photo of STOVL bulkhead forging and finished part. (possible slow loading) It’s large.

      For those mechanically inclined you might be interested in how to patch cracked and fractured airplane parts like bulkheads — google “Chapter 4: Aircraft Metal Structural Repair – FAA” — then scroll down to about page 103.

      The JPO has spoken of “blending” and “doublers” to correct the bulkhead faults. I don’t know, I assume the blending involves the application of heat, which is probably a short term effort. It isn’t covered by the FAA document. Doublers, or what we have called fishplates, are pieces (patches) of the same (aluminum) material riveted in place over the fault. These are covered by the FAA. doc.

      Faults are caused by increased stress at the failure point, resulting either from poor design, or a crack or some other stress-raiser. The holes drilled for the rivets to hold the patches also have the potential of being stress-raisers. The patch itself might concentrate stresses at a new location, and of course the patches add weight. When one bulkhead fails it transfers increased stress to the next bulkhead which then might fail, and so on.

  • TerryTee

    More on the “Junk Strike Fighter” Cracks. I was once a Supporter of the F-35 back in the early 2000’s and thought that they should only produce the F-35B because in a “Real Shooting War”, Runways will be no-existent when fighting a top Tier enemy. And the only fighters that will be able to keep in the fight will be V/STOL & STOVL ( Gripen NG) Aircraft. But have since sold my LM stock and really think this whole thing needs to be cancelled because the thing just doesn’t work as promised and now cost more than 3 F-18 Super Hornets. It’s a sham tried to make a single airframe do to many things for 3 different services now its a Cluster F___.


    Lockheed F-35 for Marines Delayed as Test Exposes Cracks,

    • SMSgt Mac

      LOL. So…. ‘earnest’. Try reading more than the headline:
      “On-the-ground stress testing for the U.S. Marine Corps version of Lockheed Martin’s F-35 jet may be halted for as long as a year after cracks were found in the aircraft’s bulkheads, Pentagon officials said.”
      In tragic news for the Anti-F-35-Program, Marine IOC is unaffected to-date.

    • Mardenstar

      Terry you know its “junk” because you work on the program and have direct insights to this problem? Also, did you take into consideration that the problem couldve stemmed from the hundreds of changes the Marines made to the initial design of the aircraft? Another armchair engineer speaking out of his derrriere

  • SMSgt Mac

    Your’s is a significantly better article than Slow Tony’s. He just picked over and reworked now stale news, so we get to hear it all over again. What’s the over-under on how long he’ll keep mining the DOT&E report?

    Perhaps a NEW series of articles on Durability Testing is in order? Since we will evidently be doing durability testing through 3 lifetimes on the F-35, the ‘story’ will be relevant for a while yet. You could educate the masses: cover the testing purposes, expectations, the history of, what test results have meant or ‘mean’. You could use the F-18 center-barrel replacement saga to illustrate to the ahistorical what this kind of testing is designed to preempt.

    • Don Bacon

      Points well taken about the “news” on poor F-35 durability, and the importance of durability testing. But it’s two lifetimes not three. DOT&E Report:

      Durability testing and analysis on the ground test articles of all three variants continued in 2013; progress is measured in aircraft lifetimes. An aircraft lifetime is defined as 8,000 Equivalent Flight Hours (EFH), which is a composite of time under different test conditions (i.e., maneuver and buffet for durability testing). In accordance with the SDD contract, all three variants will complete two full lifetimes, or 16,000 EFH of durability testing.

      • SMSgt Mac

        Two lifetimes may be the contract requirement, but the plan at least as late as 2012 was for three lifetimes for at least one variant. Here’s a slide from a decent overview of the F-35 program’s structural test program (including why the industry tests for multiple lifetimes) and findings through late 2012 found here: (PDF): http://cfile231.uf.daum.net/attach/26035D49510758FA0453E1
        Looks pretty typical, and answers the question “Why test?”.
        The plan could have changed again since then, I don’t follow the structural drama very closely.

        • Don Bacon

          Thank you — most interesting.
          Static test first, on same fixture as durability test.
          –STOVL FS 496 Bulkhead
          • Cracks Discovered at 1,471 Maneuver Hours,
          Initiating at MLG Trunnion Radius
          –STOVL FS 472 Bulkhead
          • FS472 Bulkhead Cracked at 6,750 Maneuver Hours

          Now I’ve got to find a conversion tool, pdf to jpg. –cool

          • LCondes

            Don Bacon, here’s how you can convert a PDF one page at a time using the Adobe Acrobat Distiller (not the freeware Acrobat Reader) and Powerpoint. Display the PDF page in your computer at full screen, then hit PrtSc (Print Screen). Open a Powerpoint, then Paste the PDF page into the PPT page. Do this for all the PDF pages you want to convert. Then Print the PPT using Adobe Acrobat Distiller. Next, open the new PDF file with Adobe Acrobat Distiller, then click on File – Export – Extract Images as Jpg, or PNG, or TIFF (your choice). The pasted PDF files will be extracted into the format you’ve chosen. Make sure you create a empty directory and do the extraction there. Done.

          • Don Bacon

            Thank you, I’ll try it.
            I did a dumb thing and went to the web for a “recommended” conversion tool and it fudged up my computer real good — spent some time getting the garbage out.

            Meanwhile, on the STOVL bulkhead–
            Here’s a pdf photo of STOVL bulkhead forging and finished part. (possible slow loading) It’s large.

    • http://www.breakingdefense.com/ Colin Clark

      Thank you! Context and the fullest truth possible — with our circumscribed knowledge — is what we try to deliver.
      The Editor

  • bridgebuilder78

    Can we license this Chinese design instead?


    This is everything the F-35 should have been had the Marines not ruin it with their POS STOVL version. It’s got twin engines and a FULL size belly weapons bay! The bulkheads are 3D-printed in TITANIUM!


  • ted

    Over looking what most people see as BAD news. I look at thing’s differently i guess.
    I think it’s dam smart engineering and Government thinking to do these test’s and correct faults in them before we lose any pilot’s in the air. NO ONE and i mean NO ONE can build a aircraft any better then Lockheed Martin. And Terry you should have hung onto your stock its climbing. And F-35 will meet all the requirement’s for all branch’s you can bank on that. American’s don’t build junk.

  • M&S

    It is unfortunate that the cost of the JSF is so high that people concentrate on structural reliability rather than simple replacement at a given X-point of fatigue state.

    I say this because 8-10,000hrs takes the jets out to 2060 and anyone who believes that the F-35, which is technically obsolescent today will be anything but a dinosaur anachronism, 40 years from now, is a fool.

    Indeed, Northrop Grumman has done 105KW tests on their Firestrike demonstrator SSL which shows that engagement across a 5km hemispheric defensive hemisphere with flashlight level (SOL = Speed Of Light or… :-) instantaneous attack is possible against _munitions_.

    Photos of BQM-74 drone skins exposed to this beam look like someone has put out a giant cigarette in the pieces with cratering, distortion and rupture deformation all present.

    By 2020, these systems will start to see deployment and there will be no containment of their technology base because it is in fact, all derived from civilian telecomms (fiber optics and diode pumped lasers to feed same). By 2040, you will start to see 1MW lasers and these will likely be fielded in combination with aerostat lofted relay mirrors which means 10km up through the pollutant rich troposphere will translate to 60km downrange through the high-clear stratosphere of 30-40K.

    Speaking of drones, the ability of hunting weapons: turbine powered missiles 6ft long and 300lbs with the ability to fly 500nm after launch (ADM-160 MALD) from a 5 ton truck catapult, using network optics to sweep entire regions of airspace like a flying skirmish line, are also not considered for their radical ability to detect and swarm even VLO aircraft, as well as their standoff enablers (tankers, EA, ISR). Wiping U.S. airpower from the skies for the simple reason that it is functionally slow and ponderously interdependent.

    If these drones cost 2 million dollars each (twice the cost of a baseline AIM-120C7) they will still be purchaseable at rates equivalent to 50:1 per JSF they engage. And unlike a conventional SAM, if they find no targets, they will likely be recoverable for reuse, simply by flying to a preprogrammed location and deploying a parachute (as target and recce drones do today).

    If they dogpile a single ingressing aircraft, heavy with gas, just after crossing the fence from the tanker, it will have no chance to get away or shoot them all down. Everytime one misses another will take it’s place while the first circles round again until one snuggles up to the out of airspeed/altitude/expendables/ideas and luck airframe. Killing it by handgrenade to the canopy proximity kill. This is something no piloted airforce has faced before and so they have no way to know whether they can beat it.

    Additionally, nobody has really offered a good reason for why we in fact /need/ THREE fixed wing airforces for a nation that faces no substantial challenges to it’s homeland and which has only gotten into trouble defending ‘global oil access’, to the tune of a trillion dollars spent in SWA. You know that we would not have been attacked on 9/11 if U.S. forces hadn’t been in Saudi, embargoing Iraqi oil in trade for cheap kickbacks on gasoline throughout the 1990s. Reducing our forces to the level of mercs for Arab profit (Islamic nations may not make war upon each other but they can use foreign parties to make war for them…) is disgusting and it has had terrible consequences to our nation.

    If you believe that the ability to do expeditionary warfare harm is still necessary -because- of the predictable outcome of 9/11, that’s fine. But consider this: The Marines are flat out lying through their teeth about their portion of the cost of the JSF program ‘as is’.

    They want _11_ new, microflattop, LHAs. Even if they settle for half that number, you are talking about 5X2 billion dollars. To provide this capability, they want to trade down at least 2 and as many as 4 existing CVN battle groups which have THREE TIMES the potential airwing size. And do not burn fuel oil. Yet for all of this, the LHA-6 is about 900ft long compared to the CVN-78 which is all of 1,000ft.

    To a ten million dollar DF-21D, targeted on from 1,500nm away by ROTHR radar like the Australian JORN, there is _no difference_ in these two ship classes vulnerability.

    If Sequestration goes through, the Naval JSF will all be for nothing because we will have only two carriers ready to scramble to meet a sudden emergent need. While the USMC variant will have only 250nm radius, 6 times less than the disstance at which it can be Pacific Pivot blown out of the water, along with it’s parent carrier.

    To ameliorate this, the Marines also want to have a new version of the bloated, overweight, V-22. Which they need, as tanker, carrier onboard delivery (airwings chew through spare parts at an inordinate rate) and airborne early warning and control, because currently, they have none of the above, basic, enablers of carrier airpower.

    The USN does, having just invested several billion on the E-2D program as well as the EA-18G, the KA-18 and the C-2 renovation. But none of their aircraft will land on a Marine carrier.

    The V-22 has a tiny wing which equates to less range and less payload lift to a lower ceiling than the aircraft it replaces and due to the nature of the translating wing and multiple fuel, hydraulic and mechanical transfer systems, it may not even prove possible to pressurize it and thus allow it to fly up out of the weather (necessary for improved range, sensor lines of sight and fuel transfer).

    Keep in mind, that the USN and USMC, if they get this new toy, will be paying 10 billion dollars a year for a solid decade after service entrance. And that the USAF will be paying _16 billion_ annually, in the same period.

    Finally, there will be those among you who take the “We don’t know everthing that they do and they are the ones who are puttying their lives on line…” attitude of residual hero worship. Let me make it clear that our Armed Forces are entirely voluntary. And when enough people all decide to ‘dedicate their lives to the cause of national defense’ what they are really doing is making an admission: “Because once we do, we will be set for life, since the majority can do nothing else and we as too dangerous as unemployed killers to be left without options.”

    This defacto makes the armed forced into the largest, most graft enabled, labor union in existence.

    One which is lead by college graduates rather than High School Dropout shysters. They will sell you a dire dream on the simple basis that you know not what lies they speak ‘because it’s all classified’.

    But if you refuse to be intimidated, if you apply common sense, you can see how the JSF is flawed. How individual subsystems like DAS and TTNT networking technologies are just ‘apps’ which can be downloaded to any airframe. How radar stealth is only as good as the moment it forces the threat to switch to cheaper, network, optical seekers and directed energy alternatives that require only the most fleeting of contacts to defeat the subsonic, sub-50K fighter.

    In this, the F-35 is nothing special because it doesn’t change the nature of the game relative to all the rest of the Western Airpower Paradigm threats which would have to be dealt with by the same means anyway. It doesn’t force a Near Peer enemy to change the way they do business and play technical catchup. It in fact gives them an excuse to go orthagonal to the evolutionary measure-counter reasoning.

    In a time of massive economic down turn as the Chinese unpin their (stronger production economy meets homegrown consumer market) RMB from our Dollar and the planet refuses to use the USD to trade for oil, which the 2020s will certainly represent, we cannot afford a JSF which is frankly of questionable military value, even today.

    THINK before you allow the LM/DOD/Service magicians to misdirect your gaze upon The Pledge while they hide The Turn in their other hand. Because it is this constant willingness to be fixated upon the little things that makes The Prestige seem like a greater success than the cheap Thimblerig (shell game) it actually is. You are being shown the minor flaws of the JSF to avoid having you apply your minds to the major, Doctrinal, Technical and Strategic pitfalls that it represents.

    The JSF is tactically, operationally and certainly _financially_ (three times it’s Nunn McCurdy exceedance value) not worth the cash they want you to turn your head and Think Of England in allowing to happen. We are Americans. Be proud and individual thinkers. Question _everything_ about the F-35 program and see if you don’t come to a similar conclusion as I have outlined here:

    The JSF doesn’t bring enough capabilities to the table to justify it’s 1.45 trillion dollar program price tag.