15 F-35As (13 USAF and 2 RNoAF) Grounded By “Several faulty cooling lines discovered in their wings”

15 F-35A have been grounded at Luke Air Force Base after faulty cooling lines were discovered.

Several faulty cooling lines have been identified in the wings of some F-35A aircraft at Luke Air Force Base, leading to the decision to temporarily suspend flight operations.

Noteworthy, the issue does not involve all the CTOL (Conventional Take Off and Landing) examples but 13 U.S. Air Force and 2 Royal Norwegian Air Force F-35As. Interestingly, among the 4 aircraft already delivered to the Norwegians, only the third and fourth F-35 received at the Partner Training Center at Luke Air Force Base are affected by faulty components.

Some details about the grounding were just released by RNoAF.

The F-35, just like several other aircraft, uses its fuel tanks as part of its on-board cooling system: this imply that several cooling lines have been installed inside the tanks to allow cooling liquid for the aircraft’s avionics and other systems to pass through.

During a routine depot maintenance of one of the American planes it was discovered that the insulating materials covering the cooling lines have decomposed, leaving residue in the fuel.

The subsequent inspections have confirmed the same kind of issue with other aircraft fitted with cooling lines from the same provider.

According to the Norwegian MoD the issue has been traced back to cooling lines manufactured by one particular provider that have only been installed in the wing fuel tanks of 15 aircraft – 13 US and 2 Norwegian. However, an additional 42 aircraft currently on the production line have received parts from the same provider (including the three Norwegian aircraft scheduled for delivery early next year).

“We have been very pleased with our aircraft so far, both in terms of performance and technical capabilities” says the release that goes ahead with more information about the problem: “This is not a design flaw, but is instead caused by a supplier using improper materials and improper sealing techniques for these specific parts.”

Major General Morten Klever, the director of the Norwegian F-35 Program Office says he expect Lockheed Martin to identify the appropriate measures to correct this issue, and implement these as quickly as possible.

“This appears to have been an isolated incident. We expect this to be resolved by the time we receive the next aircraft currently in production. The F-35 will be key to our ability to defend Norway over the coming decades, and consequently we have imposed very strict requirements on the aircraft,” says Major General Klever in the official Norwegian statement on the grounding.

Since not all the aircraft are affected by the issue, pilots at Luke Air Force Base will be able to continue their training using other aircraft at the base, including the other two Norwegian jets as well as the Italian and Australian examples.

Image credit: U.S. Air Force




About David Cenciotti
David Cenciotti is a journalist based in Rome, Italy. He is the Founder and Editor of “The Aviationist”, one of the world’s most famous and read military aviation blogs. Since 1996, he has written for major worldwide magazines, including Air Forces Monthly, Combat Aircraft, and many others, covering aviation, defense, war, industry, intelligence, crime and cyberwar. He has reported from the U.S., Europe, Australia and Syria, and flown several combat planes with different air forces. He is a former 2nd Lt. of the Italian Air Force, a private pilot and a graduate in Computer Engineering. He has written five books and contributed to many more ones.


  1. This is a non-issue. Lockheed Martin’s maintenance people did a good job identifying this problem before it could escalate into a real issue. Of the 57 aircraft identified with the problem, 42 are still on the assembly line. They are easily fixed.

    Since 180 have been built and fielded already 165 do not have this issue. The only people who will make a stink about this are those who are desperately looking for any reason to criticize this aircraft. But the truth is quickly becoming evident.

    Other fighters – 4th generation fighters – can’t engage this aircraft when flying against it. SAM radars can’t find it or lock on to it. It’s deadly lethal, and Russia and China are scared to death of it. Probably competing manufacturers are too. There are no planes that can match it. Compete with it. Find it, track it or shoot it down.

    If you are Norway, or Denmark – Italy, Netherlands, the UK – would you rather face the Russian AF with a fighter that will successfully engage just about every time or one that is vulnerable to Sukhoi and MiG? You tell me! Myself? I’d ask to strap on an F-35. Beer at the O-club after a mission sounds better than dead or being taken captive. In this game of life, death or captivity understand one thing. There are few second chances.

  2. Look – let’s cut through the anti-F-35 propaganda, can we? This coolant line peeling problem only affected ONE aircraft. In total, 15 had the same manufacturer’s batch of defective lines. 15 out of 180 (all models) operational. That’s 8%. Only 0.005% of the planes had the problem (1 out of 180). As a PRECAUTION those and 47 more still under production will have the part replaced. Tell me – how is this anything but a minor glitch in a very major program? Now this was a major problem found during another fighter’s development:


    You people would go nuts if this happened to the F-35. Then again, since some of you are posting from Russia and China you’ll go nuts over anything! Sorry. The program will not be canceled and if your governments start a war your fighters will be shot out of the sky by the proverbial bushel. The plane is better than anything any manufacturer in the world can build. That’s just plain fact. Accept it!

  3. That was to be expected from the A-7. To minimize costs, the Navy wanted an aircraft based on already-flying design. In the case of the A-7, it was based on the F-8 Crusader. That’s why it sailed through development.

    You can no way compare the F-35’s new high-tech development to that of the copycat A-7, and it is disingenuous of you to do so. Though having updated avionics, Corsair II was nothing extensively new. F-35 is – especially given that it is 1 plane designed for 3 services, it is stealth, and one of the planes is VSTOL. It was not polite of you to pull out that example. With me you won’t get away with it! Sorry.

    PS. A-7 was a fine aircraft, so if you flew it take no offense whatsoever.

  4. To think leroy’s troll posts are allowed and tolerated, and other’s comments exposing his trolling are censored gives an idea of how this “blog” is one-sided, and possibly sponsored by

    • Your comments here are moderated each time they don’t add any value to the discussion. If you counter Leroy’s posts with some facts or showing he’s biased you won’t be moderated. But I don’t think anyone here wants to read you saying that “he’s probably a wannabe Lockheed PR employee” once more.

      • If a commenter supports F-35 they are called Lockheed Martin “employees” and “sock puppets”. If a website simply reports on the aircraft, as The Aviationist does in a fair and unbiased way, they are accused of being financially supported by LM or one of the subcontractors.

        This is how people on the Internet try to censor both commenters they don’t like and stories about this aircraft. I’m glad it is a tactic that doesn’t work here. As far as this website is concerned, I see no bias for or against F-35. You just report what’s happening. As for commenters, most are either for or against. Having both points of view leads to a better discussion.

  5. Wow. I mean damn. Did you just equate a subsonic, vanillia strike aircraft, based on a pre-existing fighter with years of service, to a supersonic, stealthy, STOVL aircraft?

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