Flight Maneuver Hints at Cause of F-35 Fire


The U.S. Defense Department official in charge of the F-35 fighter jet program said a previous flight test maneuver played a role in an engine fire that led to a temporary grounding of the fleet and ongoing flying restrictions.

Speaking during a defense conference Wednesday at the National Press Club, Air Force Lt. Gen. Christopher Bogdan said three weeks before an F-35A made by Lockheed Martin Corp. caught fire during takeoff June 23 at Eglin Air Force Base, Florida, it was flown in a manner designed to test the performance of its g-force, roll and yaw characteristics within designed limits known as the flight envelope.

While the maneuver only last two seconds or so, it caused excessive rubbing between the titanium blade in the fan section of the F135 engine made by United Technologies Corp.’s Pratt & Whitney unit and the surrounding material, Bogdan said. The metal reached temperatures of as high as 1,900 degrees Fahrenheit — compared to the normal level of about 1,000 degrees — and resulted in micro-cracking, he said.

A few weeks later, during the fateful takeoff, the blade came apart and actually pierced the left aft fuel tank, engulfing the rear of the plane in flames, Bogdan said. “It was the fuel tank that caught fire,” he said.

While the pilot escaped from the aircraft unharmed, much of the plane was destroyed. Bogdan declined to say it was a “total loss” because he said the program office plans to reuse parts that are salvageable. But it’s safe to assume the incident was a Class A mishap, which is defined as accidents resulting in fatality or total permanent disability, loss of an aircraft or property damage of $2 million or more.

The Joint Strike Fighter is the Pentagon’s most expensive weapons acquisition program, estimated to cost a total of $398.6 billion for a total of 2,457 aircraft. That breaks down to a per-plane cost of $162 million, including research and development.

Under the most recent production contract with Lockheed, the department in 2013 agreed to pay $112 million per F-35A, $139 million per F-35B and $130 million per F-35C. Those figures, known as unit recurring flyaway costs, include the airframe, engine, mission systems, profit and concurrency.

The Pentagon in its budget for fiscal 2015, which begins Oct. 1, requested $8.3 billion for 34 of the aircraft, including 26 F-35As, 6 F-35Bs and 2 F-35Cs. The House Appropriations Committee voted to buy an additional four aircraft, for a total of 38, while the Senate panel agreed with the Pentagon’s request — a difference that will have to be resolved in conference negotiations. Congress hasn’t yet passed a defense spending bill.

Eight countries have committed to help develop the F-35, including the U.K., Italy, the Netherlands, Turkey, Canada, Australia, Denmark and Norway. Also, Israel, Japan and South Korea plan to buy production models of the aircraft.

There are currently about 100 F-35s in the U.S. fleet, Bogdan said. Pratt & Whitney has delivered roughly 150 F135 engines, he said.

Bogdan said Pratt & Whitney officials have vowed to cover the cost of the engine fix, which will probably include redesigning that part of the propulsion system to create more space in the so-called trench area. He declined to specify how much it will cost until the program office completes a root-cause analysis, expected later this month.

A prototype part may be tested as early as mid-October, Bogdan said. Meanwhile, the program office is developing a new engine break-in procedure as a short-term fix to better analyze how it performs under increasing loads, he said. Even so, if the planes don’t resume regular flight testing later this month, the program could be delayed by a month or more, he said.

Separately, Bogdan said, Pratt & Whitney has halted further deliveries of the F135 engine amid plans to sue a supplier for providing “suspect” titanium. The Pentagon’s Defense Criminal Investigative Service and the Air Force Office of Special Investigations are looking into the matter, he said.

The suspension affected 10 engines that probably would have been delivered by now and four more that are not yet under contract, according to an article by Tony Capaccio of Bloomberg News.

The F-35 missed its highly hyped international debut in the United Kingdom this summer. Four of the F-35B short take-off and vertical landing models were scheduled to appear at multiple events in the U.K., culminating with a flight demonstration at the Farnborough International Air Show outside London in July.

About the Author

Brendan McGarry
Brendan McGarry is the managing editor of Military.com. He can be reached at brendan.mcgarry@military.com. Follow him on Twitter at @Brendan_McGarry.
  • Robbie

    Well, that’s what the test program is for. Glad they found it early…..

    • Nessuno

      A test program with a 100 delivered units…..?

      • meow

        Good point.

        LM’s response: Look on the bright side, it could have been 3640 units.

      • Bernard

        We can only wonder how many more billion it will take to make this thing air worthy much less combat worthy. Our tax dollars at work. :-(

        • camden

          Let’s start with 10 billions and 10 years.

          LM = Loser’s Mechanic.

    • rtsy

      Not early enough.

  • ZYX

    Wow – this is rather major. Glad they caught it, and good on P&W to cover the cost of the fix, unlike some defense contractors I know of. Very astute of them to realize that their reputation is on the line whenever a mishap occurs with a part they are responsible for. Especially true for engine manufacturers.

    Still, I’m rather surprised that it was an issue with the design of the fan blades.

  • ChristopherS

    Lets see a fire and a lack of titanium for the engine. Congress should be thinking hard about canceling funding for the F-136.
    They should stop funding this white elephant altogether, build the planes already purchased and look into purchasing a 4.5 interim fighter. Maybe turn the T-X Program into the FT-X.Than put the F-35 technology into the winning fighter.
    As the USAF is never going to get the 1700 their asking for. As IOS won’t be achieved by 2015 or the next five. By then Russia and China will have their own fifth generation fighters online.

    • Tiger

      The point of no return has been passed. Your idea is DOA.

    • Scott

      No one said anything about a “lack of titanium” for the engine, perhaps reading comprehension is not your strong suit. So you think if you just stopped funding of an 20 year research and development program and started all ofer from scratch it would be cheaper… Brilliant. The F35 is having the same problems every new high tech aircraft has nothing more. If the USAF is never going to have the numbers they are asking for, what makes, how does spending the same amount re-developing a new plane change that? Oh by the way, you think Russia and China don’t have problems developing new aircraft?

      • Ben_RG

        Not making any judgement on the F-35 series but rather a more general point:

        It doesn’t matter if you spend $20 or $20 billion; if it’s no good, it’s still no good. You’ve just wasted more money and should be turning the spigots off with more urgency.

    • wpnexp

      No one has implied that this was problem that would invalidate the program. It has only been related to one specific maneuver so far. When the Russians had an engine fire on the PAK-FA has anyone suggested it be cancelled? With 18,000 fligth hours, it is actually amazing that more problems haven’t occurred.
      For a little perspective, we had an F-15 fall out of the sky the other day. By your standard we should now stop flying F-15s? Most of the planes systems are already mature with the IOC Block 2B software nearly ready for release. To fully get what we are paying for, we will need to continue to improve the software, incorporate more weapons, and improve the system integration, but the plane has already demonstrated considerably more value than the planes it will replace. With inflation, research and development, testing and so on, you FT-X would likely cost the same as the F-35 while providing less capability.

  • Big-Dean

    hahahahahahahahahahahaha, the act of flying causes engine failure! Well, in that case we had better not fly them anymore.

  • Puffer

    Proof this plane is a dud!

  • BlackOwl18E

    Its official. Naval Aviators HATE the F-35 and want the Advanced Super Hornet. The full 2014 Navy Retention Study is out:


    Favorite paragraph:

    When asked if the Joint Strike Fighter was the “right aircraft for Naval Aviation,” 60% “strongly disagreed” or “disagreed”, and 22% were neutral. Only 10% “agreed” or “strongly agreed.” Conversely, when asked if they would prefer an Advanced Super Hornet over the Joint Strike Fighter, 62% “strongly agreed” or “agreed,” and 20% were “neutral.”

    Keep in mind, these guys are the experts. They put their lives on the line in the aircraft and they are more knowledgeable about the subject than anyone.

    • William_C1

      Back in the early ’90s the naval aviators wanted the Super Tomcat. They were overruled. In the end they have no control over whatever decision gets made.

      The truth is naval aviation does NOT have the “right aircraft” for the next two decades with either aircraft. They need something more capable than either to clear the way for Super Hornets or JSFs to do their work.

    • Tiger

      Those Experts have zero fight hours in the “35C.” There is nothing Super or advanced about the Hornet. Like a old Chevy Cavalier with a wing & big muffler added.

      • xXTomcatXx

        My thoughts exactly. Until the C variant gets into enough hands, judgement should be reserved.

    • FWGuy

      You left out the rest of the statement, which basically says most of those surveyed have never flown the F-35 and have no clue to its real capabilities. I know those that have flown are deeply impressed about the jets capabilities.

      “One commenter, a JSF pilot, noted that much of the community has yet to see the JSF in action, which — when coupled with years of negative press — may be one reason for the deep skepticism about the F-35.”

    • xXTomcatXx

      Keep in mind, these guys are the aviators that love the birds they’re in and would happily fly it until the end of their careers. None of them have landed one on a carrier deck to make a fair comparison anyways. How much of their perception is based of media coverage of the program vs real-world experience? This is no different than asking you or I for our opinions.

      Opinions are like something, everyone’s got ’em.

    • wpnexp

      Written like a complete F-18 devotee, with no vision of the future. Black Owl, I scanned all the comments on the article in question, and virtually none of them even mentioned the F-35 or your vaunted Advanced Super Hornet. (And I am not against the Navy buying ASH if the money could be found either). Second, one snippet of the article talked about the F-35, one wonders what positive remarks on the F-35 were left out. Third, with fewer than 20 Navy pilots now flying the F-35C, it is hard to imagine that those pilots remarking on the F-35 would even know about the plane. I recall talking to an F/A-18 pilot in the around 1996 that had no idea or understanding of what an AESA radar was, while I as a non-aviator knew much more about them than he did. It is easy to be bllish about what you know, and critical about things you don’t understand. I suspect that is the situation here. Finally, just reading a blog by someone going as cdrsalamander tells you a lot. Try reading the AirInternational special on the F-35. It is a critical and complete look at the plane that is very enlightening.

      • BlackOwl18E

        wpnexp, your past posts just now have shown me that you have such a lack of knowledge of this subject that I won’t debate you because you have some SERIOUS reading to do before I can take you seriously.

        I bet you didn’t even click the link in the blog and examine the studies yourself. I used the blog’s page because it summed up the part of the study that I wanted to focus on. I don’t actually follow that blog, but the link it has leads directly to the Navy’s website where the study results are open for viewing.

        I’m not going to comment on anything else you post until you’ve shown me you actually have an understanding of this material. By the way, a private conversation you had with a pilot all the way back in 1996 is a poor source for an argument in 2014.

      • Mark

        If you had watched the video I posted you would know the tail hook issue was solved by doing two basic things. 1 they sharpened the hook and applied more downforce. Testing is complete. What is next will come in the next few months. They will be taking them to the carrier.

  • JayB

    Eight years after first flight, and with one hundred airframes procured, the flight test team performs a two-second maneuver designed to test the g-force performance of the F-35. Result: The airframe violently burns to the ground. (Luckily, the test pilot managed to escape unharmed – Thank you, God.)

    I don’t know whether to laugh, or commit suicide. This program makes Shakespeare’s Romeo and Juliet seem like a feel-good story. I’m sorry about the gloom, but this aircraft development and aquisition program is the most botched in military history.

    • NathanS

      This is hardly anything new – and especially for Pratt & Whitney who have been down this road before.

      Even after the official launch of the Boeing 747, accelerating too quickly caused the Pratt & Whitney engines to explode. Pratt & Whitney were very slow moving in providing a fix. So Boeing decided to take the CEO of Pratt & Whitney for a test ride. While in the air, the test pilot said, “I want to show you something”, and pulled the throttle of engine 1 to full, and the engine exploded. He looked at the CEO who was visibly shaken, and put Engine 4 to full throttle, and it exploded. He put his hand on Engine 3, but the CEO stopped him, and said, “Okay, okay, I’ll make sure it gets fixed”. Within a week they had a fix to the problem.

      And surprise, surprise – the jacket of the turbine blades did not provide enough room for the blades to expand due to heat. Sounds very familiar doesn’t it?

      As it turns out, the Boeing 747 is now considered one of the most successful commercial airliners, and the P&W engines ended up being quite reliable.

      • William_C1

        It was a similar story with the F-15 and F100 engine although not quite so drastic failures. The F100s were prone to compressor stalls, were wearing out too quickly, and the afterburner had a bad habit of “flaming out” resulting in a hard start when it did ignite again. It took awhile to fix but the F100 has one of the best safety records for USAF engines.

    • xXTomcatXx

      Because this is the first fighter program that had to redesign it’s engine…

      Oh wait! The Great Engine War was our last go around. Silly me.

    • SMSgt Mac

      It’s the story of all jet engines considered ‘advanced’ for their time. The F135 is no different, except it is undergoing less drama than a lot of predecessors thanks to advanced design and test techniques. Earlier engines didn’t have the same benefits. It’s just that you’re seeing a surplus of drama queens and mistaking them for real drama.

    • wpnexp

      JayB – You are wrong on several points. While the flight may have been used to test the aircraft, it was at Eglin, where the planes are used for training, not test. The flight did not burn up during the test but on a completely different flight, as the plane had not even lifted off when the accident occurred (which allowed the pilot to avoid ejecting to his luck. The plane didn’t burn to the ground either, and many parts will be salvaged for use in other planes. Most of the very expensive avionics likely survived. It is hardly the most botched program in history, but certainly is very ambicious. Things like the Goblin fighter and the nuclear bomber, were far more bizarre. The F-104 built for many of our allies were known as flying coffins. Consider the A-10 Flying Dorito if you want a botched program, this is not a botched program. Even the great P-1 Mustang was not successful, until it was matched with the Merlin engine. Making the plane better will take time, and many testers are doing their best to make it that way. But to have the best plane, it has to be tested completely. It is good that the plane will be the most tested plane in history as it will make it one of the most effective. But, testing is about finding problems and fixing them, not sticking your head in the sand and ignoring them.

  • Bronco46

    Many weapons systems have developmental problems like these. The one that cost the most lives would have to be the M-16; which is now a well respected weapon, that many different calibers have been based on. The P-51 was also a dud, for a while. And there have been may other systems that needed time and research to perfect. Granted these are expensive but for this level of technology; with the level of government subsidies seen in Europe.

  • Mitchell Fuller

    What has wings but can’t fly? The F-35. As a contractor in Fort Worth this joke was told to me by an LM employee………

    • Doc

      The Eastern Lubber Grasshopper. But, it’s toxic, brightly colored and smelly. Unlike the F-35.

    • wpnexp

      So, how is it that the plane has over 18,000 flight hours? Pretty stupid remark I would think.

  • Tiger

    “Pratt & Whitney has halted further deliveries of the F135 engine amid plans to sue a supplier for providing “suspect” titanium.”

    “You mean the guy in the green hoddie under the tracks is a bad titanium dealer? I thought it was pure stuff?” Says the THe P&W guy buying it by the dime bags at 3am……..

  • josh.p

    Omg… what is it with the f-35? It seems like just one problem after another is just happening with this thing. anybody thinks we should have continued production of the f-22 raptors?

  • fly4vino

    Sadly the military seems to be infected by the same bulls_itspeak that flows from the White House on an hourly basis

    “Bogdan declined to say it was a “total loss” because he said the program office plans to reuse parts that are salvageable.

    Gen Bogan – If I borrowed your car and returned it in a wheelbarrow of smoking parts you would be insulted if I claimed I had not totalled your car because the rear view mirror was usable after the glass was replaced

    Yes, I know you don’t want the press to be able to say the $XXX million dollar airplane was a total loss.

  • 009

    To think this is a single engine aircraft-SCARY!

  • Rich

    Lots of Monday morning quarterbacking going on. Just look into the history of some of the “Century Series” fighters and see how many of them crashed during development and early deployment.

  • Ben_RG

    I saw on another site that Pratt & Whitney are complaining that the titanium they’ve been using in the engines is of too low quality. I thought that this might explain the issue with the turbine blades. However, this article seems to indicate a design fault in the F135 itself. Given that Lockheed and Pratt are 10 years into this project, it doesn’t say much for their quality control standards that issues like this are only now being identified and then only when a test aircraft is destroyed.

    • tiger

      The guy in the green hoodie said it was good stuff…

    • Rod

      I wonder if the stress imposed by the high g maneuver caused the blade to elastically deform and rub on the surrounding material. Once you get friction, you get heat. Heat could have caused the metal to creep and permanently deform; it could have also expanded the blade and put it into compression, causing micro-fractures. Either way, that leads to more friction and more heat.

      These issues can usually be predicted using mechanical properties obtained from vendor; the performance of the alloy may have been exaggerated or it could have been produced improperly.

      I imagine high g maneuvers are difficult to test in a lab and is the reason why they never noticed the issue.

  • NRO

    Just remember, the F-35’s engine is single-sourced to Pratt & Whitney. The Program Office decided to cancel the second engine sourcing to save money.

    • SMSgt Mac

      And just remember when that happened the F136 was well behind the F135 in development and it was having its own similar problems simultaneously. So what?
      The conditions that brought us the first Great Engine War aren’t present today. Well, except for GE trying to stir up some business.

  • tribulationtime

    100 F-35, 150 engines, and 8.3 bn worth production contract and F-35 Fighter Aircraft CAN PULL G´s TOO LONG. I find hard to belive how this program is run. I promiss I have real curiosity ¿What Military buy when they select between both proposals?

    • wpnexp

      The engine will be OK. It has gone through many hi-g tests and high AoA tests too. One accident is not enough to stop a whole program.

  • William_C1

    I do wish they’d give more details about the specific maneuver in question the aircraft did. Without such details you have the usual suspects going “lol F-35 can’t do a simple turn”.

    • Tony D

      It seems just turning on the engine will cause a fire. Ten years of research and building the engine wasn’t enough. How about using a model they have on the shelf that they know works.

      • wpnexp

        The F-135 is actually a growth model of the F-119, so it is somewhat off the shelf. After 16,000 hours, it is pretty good proof that “simply turning on the engine does not cause a fire.

  • Mark

    Here is what is being done to fix this issue.

  • johnny paycheck

    A single engine fighter jet that under high stress may have an uncontained turbine failure into the fuel cell. Yep, let’s buy a bunch of those.

  • Big-Dean

    Pigs can’t fly, that saying has proven to be so true!

  • FedUpWithWaste

    The F-35 is a hornswoggle. Military- Industrial crap. Dump it, upgrade our Super Hornets,
    F-16s, F-15s, etc. Why, we could even build NEW versions of the aforementioned aircraft, and have perfectly serviceable. 4.5 gen weapon platforms! And save billions which we are going to need extirpating ISIL.

  • oblatt22

    The F-35 turns like a whale, a whale that has a heart attack when it tries to go round the corner.

    No wonder the F-35 pilots motto is “eject at the merge”