In a tweet of Donald Trump (which was also carried without commentary in this regard by the Washington Post) he says

So many people conveniently forget that Turkey is a big trading partner of the United States, in fact they make the structural steel frame for our F-35 Fighter Jet.

What is Trump talking about here? I'm guessing at best it's the frames for the F35 that Turkey is using (not the US). But even then, is the claim true?

  • 4
    it seems unlikely that a large part of any aircraft, escpcially a high-performance one would be made of steel.
    – Jasen
    Oct 13, 2019 at 4:57
  • 3
    @Jasen: that's what I thought too. Also Trump is not exactly an engineer or known for the technical accuracy of his statements in this area. We had another question here about his claims about "invisible" aircraft. Oct 13, 2019 at 4:58
  • 2
    @Jasen especially structural steel...
    – Michael
    Oct 13, 2019 at 20:01
  • chrome-molebdinum steel aparrenly has an excellent mass to strength
    – Jasen
    Oct 19, 2019 at 7:15
  • if you allow him some rethorical usage, as "steel" for "metallic" and "structural" as an intercalate (to be reinforced with "literally", if you are born after 1980s...) the sentence makes perfectly sense
    – EarlGrey
    Oct 3, 2023 at 9:25

3 Answers 3


Bearing in mind subsequent changes (including the 2020 phase-out currently in the works), a 2013 press release by Northrop Grumman said:

Turkish Aerospace Industries, Inc. (TAI), a subcontractor to Northrop Grumman, delivered its first F-35 Lightning II center fuselage to Northrop Grumman and Lockheed Martin at a ceremony held at TAI's facilities in Ankara, Turkey, on Dec. 11, 2013.


Once the program reaches full rate production, TAI will support F-35 final assembly lines in the United States and Italy by shipping one center fuselage every 10 days. TAI's center fuselages will be integrated into the Turkish F-35 aircraft as well as other participating nations' aircraft.

In addition to building center fuselages as a Northrop Grumman subcontractor, TAI is the single source for center fuselage metallic assemblies for F-35A, selected composite components for all F-35 variants, and is one of two sources for composite air inlet ducts for F-35A, and air-to-ground alternate mission pylons for all F-35 variants.

Note that the F-35A variant is used by the US (and also by other countries).

And from a 2009 press release (in which the CTOL variant probably refers to the later F-35A):

The assemblies from TAI will be used in center fuselages for F-35 conventional takeoff and landing (CTOL) variants. Northrop Grumman, a principal member of the Lockheed Martin-led F-35 industry team, is currently assembling those CTOL center fuselages in Palmdale, Calif., as part of the second phase of F-35 low rate initial production.

"We are very encouraged by TAI's steady progress in maturing the production and assembly processes that will be required to eventually produce 400 center fuselages for the program," said Mark Tucker, vice president of tactical systems and F-35 program manager for Northrop Grumman's Aerospace Systems sector.

TAI is scheduled to produce this metallic structural assembly for all CTOL center fuselages currently planned for the F-35 program, added Tucker. All of the assemblies will be produced in TAI's manufacturing facility in Ankara, Turkey. Northrop Grumman previously produced the assembly in Palmdale.

Northrop Grumman is responsible for the design and production of center fuselages for all three variants of F-35 aircraft: CTOL; short take-off, vertical landing; and carrier-compatible. The F-35 Lightning II program expects to build more than 3,100 aircraft.

So while TAI was scheduled to produce only a fraction of the total center fuselages (as a second source), they were intended to be the sole source of the "center fuselage metallic assembly" for the CTOL variant (F-35A).

  • 3
    Why is this the bottom answer when it most clearly and directly answers the question?
    – Wildcard
    Oct 14, 2019 at 8:11
  • @Wildcard – this is a textbook example of flock voting. :) The oldest answer was here early so it gained its momentum as the only answer. But since then it keeps its lead by gaining new votes although it is of worst quality of all 3 answers.
    – miroxlav
    Oct 14, 2019 at 8:43
  • @miroxlav And now (as I write) this is the top answer. Oct 14, 2019 at 15:03

The F-35 made by Lockheed Martin is a joint venture by multiple countries; among others, USA, Canada, Italy and Turkey. Turkey was part of the deal and they helped funding the development of the jet. They were expelled from the program after the deal to buy the Russian S-400 missile defense system.

Ellen Lord, Pentangon acquisition chief, commenting on the event:

At this point the Turks have made a decision. We have said that the F-35 and the S-400 are incompatible. We will work forward at this point to unwind the relationship

It was decided that Turkey’s role in producing parts for the F-35 will end by March 2020.

At this point we are unable to say what parts Turkey really produced and if the production stopped (or slowed down). All participants of the production had their part in making some parts of the fighter jet that was then put together by Lockheed Martin.

  • 4
    There are more details here on that eviction, although the US could reverse trend again if the circumstances make Trump change his mind, methinks. Also this answer was neither confirming nor denying my main question regarding a specific component. Oct 11, 2019 at 15:10
  • 7
    Does incompatible mean you can't shoot an F-35 with an S-400? ;) Oct 12, 2019 at 20:29
  • > At this point we are unable to say what parts Turkey really produced really? see the other answers. I don’t get why this one is top Oct 14, 2019 at 8:17
  • This answer doesn't answer the actual question and is just about the current project status.
    – matt_black
    Oct 14, 2019 at 10:39
  • @rackandboneman It means two fighters go up, but only one comes back down (in a single piece). Oct 14, 2019 at 14:02

According to Turkish Aerospace Industries (TAI)

One of the most complex structural sections of the aircraft, "F-35A Center Fuselage" is produced by TAI as a second source.

Second source means "a company that is licensed to manufacture and sell components originally designed by another company (the first source)"

  • 4
    For those who don't know what that last bit means en.wikipedia.org/wiki/Second_source Oct 11, 2019 at 15:01
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    Also, the first source for that component is apparently Northrop Grumman's factory at Palmdale (even though Lockheed is running the overall F35 program, i.e. is the "industry lead"). Oct 11, 2019 at 15:15
  • Actually the (whole) center fuselage is not the same thing as the metallic assembly thereof. See my own answer in which Northrop Grumman says TAI is the single source (since 2013 or so) for that assembly. Oct 11, 2019 at 21:39

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