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.

23 Comments on "Flight Maneuver Hints at Cause of F-35 Fire"

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

  2. 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.

  3. 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.

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

  5. Proof this plane is a dud!

  6. 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.

  7. 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.

  8. 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.

  9. 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………

  10. "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……..

  11. 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?

  12. 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.

  13. To think this is a single engine aircraft-SCARY!

  14. 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.

  15. 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.

  16. 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.

  17. tribulationtime | September 4, 2014 at 2:50 pm | Reply

    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?

  18. 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".

  19. Here is what is being done to fix this issue.

  20. johnny paycheck | September 4, 2014 at 6:56 pm | Reply

    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.

  21. Pigs can't fly, that saying has proven to be so true!

  22. 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.

  23. 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"

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