This is the mechanical equivalent of vibe coding. 3D printing itself isn't exactly to blame but the negligence of the company that created and sold this part and omitted it's use from an inspection.
Just because a part has the shape of an engineered part does not make it compatible, strong, safe, and fit for purpose. This part could have likely been fine if it used a different material such as Ultem.
In what way is this like vibe-coding -- or do you just mean both are bad?
According to the report:
> The aircraft owner who installed the modified fuel system stated that the 3D-printed induction elbow was purchased in the USA at an airshow, and he understood from the vendor that it was printed from CF-ABS (carbon fibre – acrylonitrile butadiene styrene) filament material, with a glass transition temperature3 of 105°C.
I think by vibe coding he means taking these things at face value instead of rigorously looking if they are up to the standard. When coding you would rigorously look if the code is good / produces any bugs. With vibe coding, you give a prompt and just accept the output, which might be full of errors and blow up (or melt). The analogy is that, yes you can print airplane parts, but they were sloppy and just accepted them at face value instead of rigorously looking if they are up to the required (bug free) standard, ie they wont melt.
The problem is we have different terms that all mean doing something without real risk management or analysis in software. Both "cowboy coding" and "vibe coding" mean the same thing, if you remove the agent doing the production.
And since vibe coding is so recently coined, I think a lot of people take it to specifically mean "LLM" and not some generalized "any third-party agent".
Then, a vibe coded engine part sounds like it would need a generative AI producing the CAD file that is then printed. And it might have some bizarre topology like a Klein bottle or some fever dream.
>I think by vibe coding he means taking these things at face value instead of rigorously looking if they are up to the standard.
Yeah, exactly -- which is why it's a stupid phrase for what happened here.
Not every negligence is somehow equatable to an AI pitfall, it's just on parents' mind so it's the only metaphor that gets applied.
A poorly fit hammer in a world of nails.
I say this as an engineer/proprietor with years of additive manufacturing experience, it's insulting. A poorly chosen and wrongly used process conveys nothing about the underlying fundamentals of the process itself -- it conveys everything about the engineer and the business processes that birthed the problem.
Similarly if I came across a poorly vibe-coded project I wouldn't blame Anthropic/oAI directly -- I would blame the programmer who decided to release such garbage made with such powerful tools..
tl;dr : it's not vibe-coding itself that makes vibe-coding a poor fit to rocket science and brain surgery -- it's the braindead engineer that pushes the code to the THERAC-25 without reading.
I think the idea was that 3D printing made doing a thing accessible, previously required solid fundamental knowledge (and very expensive kit). Now you can just take some specs off the internet and press go.
The comparison does not seem as absurd to me as it does to you. vOv
The lesson here is that one should never attempt analogies on HN, because people can't just relax and try to see the point of the analogy. They are compelled to fixate on the fact that an analogy is different from the thing it is being compared to.
I feel like Hacker News commenters love to make analogies more than average people in your average space, though. You can't come across a biology/health topic on here without someone chiming in with "it's like if X was code and it had this bug" or "it's like this body part is the Y of the computer."
Analogies can be useful sometimes, but people also shouldn't feel like they need to see everything through the lens of their primary domain, because it usually results in losing nuances.
3D printing is to mechanical engineering what vibe coding is to computer science.
With the rise of accessible 3D printers that can print engineering materials, there are a lot of people who try to create functional parts without any engineering background. Loading conditions, material properties, failure modes, and fatigue cycling are all important but invisible engineering steps that must be taken for a part to function safely.
As a consumer with a 3D printer, none of this is apparent when you look at a static, non-moving part. Even when you do start to learn more technical details like glass transition temperature, non-isotropic strength, and material creep, it's still not enough to cover everything you need to consider.
Much of this is also taught experimentally, not analytically - everyone will tell you "increasing walls increases strength more than increasing infill", but very few can actually point to the area moment of inertia equation that explains why.
3D printing has been an incredible boon for increasing accessibility for making parts in small businesses, but it has also allowed for big mistakes to be made by small players. My interpretation is the airshow vendor is probably one of these "small businesses".
You don't need to be able to mathematically jerk the equation off to understand why increasing material at the perimeter adds more strength than the center (within reason and in typical cases) or why you probably shouldn't use something that melts around 200deg in an engine bay.
Note that the actual material used has a glass transition temperature around 50 degrees, not 200. If the part was actually made from ABS-CF (as the pilot thought it was) it'd stand a decent chance of surviving for a long time given that it gets a lot of air cooling.
Everything you need to consider is really not that much when it comes to most typical consumer 3d printing projects. Mostly because they are usually about stuff like "fixing a broken tashcan". The engineers who made that bullshit plastic part that broke after a year probably knew all about area moment of inertia, but that doesn't mean I need to to print a replacement part that lasts longer - or not, in which case I'll just iterate on my process.
I really don't get the dismissiveness, and frankly, I've never experienced that from engineers in my life. They just seem delighted when someone, kid or adult, tinkes with additive manufacturing.
Hmm, I suppose the analogy could be interpreted as dismissive, which is not my intent.
I think both vibe coding and 3D printing are wonderful things. Lowering the barrier to entry and increasing technology accessibility allows those without formal training to create incredibly capable things that were previously difficult or not possible to do.
What I meant to specifically highlight is the 3D printing of functional parts that have some level of impact on safety, things that can lead to significant property damage, harm, or loss of life. Common examples include 3D printed car parts (so many) and load bearing components in all sorts of applications (bike mounts, TV mounts, brackets, I even saw a ceiling mounted pull-up bar once).
This isn't to say it can't or shouldn't be done. What I'm saying is that both on the digital side (files for personal use) and the production/sale side (selling finished parts), there is no guarantee of engineering due diligence. 3D printers enable low volume small businesses to exist, but it also means that, purposefully or not, their size means they can go quite a while without running into safety regulations and standards meant to keep people safe.
I call bullshit. 3d-printing is just a manufacturing method. Basic woodworking is much cheaper and more accessible than 3d-printing, do you call it vibe-coding?
If you carve a wooden part with "the right shape" for an engineering application that the part lacks the physical properties that allow it to perform under load stress ... then yes, that's vibe carving.
Looks good - falls apart in practice, and a junior can't tell the difference as they "look the same" to the inexperienced eye.
From practical experience, you cannot just replace a tyre on a car with any old bit of wood - you really need to use hard wearing mulga (or equivilant) as an emergency skid. (And replace that as soon as possible)
What you're describing is more like someone who doesn't know computer science principles hacking on code, manually. Part of the definition of "vibe coding" is that AI agents (of questionable quality) did the actual work.
This whole thread is a stretch, IMO. But, I like this phrase.
As a fabricator (large wood CNC, laser cutting and engraving, 3D Printing, UV Printing, Welding). I put engineering into a whole different job scope. I can make whatever you tell me really well, not vibe-carving.
I don't necessarily write the specs or "engineer" anything. I'm just saying, don't blame the medium, 3D printing. The fact is a fabricator is not necessarily an engineer, regardless of the medium.
Don't get me wrong, wood is great, I've made a lot of things and replacement parts from appropriate woods.
Using scrublands wood (slow growing tough long grain mulga) as a skid when a rubber tyre destroys itself is an old old hack passed on by my father (he's still kicking about despite being born in the early 1930s).
Point being, I don't blame processes (3D printing, etc) for part failure, that comes down to whether the shape and material are fit for purpose, whether material grain structure can be aligned for sufficient strength if required, whether expansion coefficients match to avoid stress under thermal changes, etc.
Engineering manufacturing can sometimes be suprisingly holistic in the sense that every small things matter including the order in which steps are performed (hysteresis) .. there's more t things than meet the eye.
In the report they tested samples of the part and found that they actually had glass transition temperatures of 52.8°C, and 54.0°C... so sounds like the owner fell victim to false advertising.
This is an experimental homebuilt aircraft, so the regulations on manufacture and replacement parts are much less stringent than commercially sold aircraft.
Also, the part it was replacing was a fiberglass part in an epoxy resin, with a glass transition temperature of 84°C. So the 105°C glass transition temperature of the replacement part should have been better than the original.
However, the original had an aluminum tube supporting the inlet, which provided extra structural support beyond fiberglass epoxy resin. And upon testing, the actual glass transition temperature of the 3D printed part was 52.8°C for one sample and 54.0°C for another, so much lower than expected.
Now, because the regulations are much less strict for experimental homebuilt aircraft, there may not be the traceability to figure out where in the chain the issue came up. Was it a bad batch of filament? Did the person making the part use the wrong kind of filament? Who should have tested the glass transition temperature of a coupon of the same material as the replacement part? Did the 3d printed material glass transition temperature change over time, possibly due to something like fuel or exhaust fumes?
The recommendation from this report is to disallow 3d printed replacements for this part, but it should be possible to do with the right material and proper testing and analysis (as well as leaving in the aluminum tube for additional support), as this is an air intake and it should be possible to find a 3d printed material that can withstand the kind of temperatures an air intake is subjected to, given that the original part is a fiberglass with epoxy resin.
The report further states that the part included in the original design (part of the kit) was made of a carbon fiber composite where the epoxy had a listed glass transition temperature of 84⁰C. If there is an element to be critical of along these lines it's that the part as originally designed is supposed to include an aluminum tube at one end that may stiffen the part - the report makes no conclusions whether it truly would have, but notes that the actual glass transition temperature was found to be much lower than listed, and lower than that of the epoxy used in the original design.
The person who coined the term vibe coding is now doing a soylent-like [1] experiment where he only will read content that has been regurgitated by an AI [2], so yes I think it's a fair characterization of "vibe coding".
> Isn't this simply a part that shouldn't have been allowed to be sold based on it being both faulty and also misleading?
"Faulty and also misleading" pretty much describes the code output by vibe coding. And don't get me wrong: I use LLMs daily to help me write functions / write test cases / find bugs / find edge cases / explain error messages etc. But I don't vibe code entire parts like that part that melted.
The vendor selling the 3D-printed part at an airshow probably didn't think: "I'll deceive pilots." They likely thought: "I can 3D-print this part to spec, it looks right, it fits, and pilots will be happy." The capability to create professional-looking outputs outpaced the discipline required to validate them.
Same with vibe coding: the LLM isn't lying. It's producing code that passes basic inspection. But both technologies have collapsed the cost of creating something that looks production-ready while preserving all the ways something can fail in actual use.
Before 3D printing and LLMs, there were natural friction points that forced validation:
• Manufacturing a metal aircraft part required industrial equipment, precision tooling, material selection expertise. The process itself embedded quality gates.
• Writing professional software required years of training, code review practices, deployment infrastructure. The difficulty forced rigor.
Now, both technologies let anyone produce outputs that visually and functionally resemble professionally engineered work without any of the underlying validation:
• A 3D printer can output a part that looks dimensionally correct, has proper tolerances, fits perfectly—but the material choice was never stress-tested against thermal cycling.
• An LLM can generate code that compiles, runs, produces correct output for test cases—but has no error handling, SQL injection vulnerabilities, or memory leaks that only appear at scale.
This is a relatively new failure mode where professional appearance becomes decoupled from professional rigor. And customers can't easily tell the difference until something breaks.
I think a more useful definition of vibe coding is "something you can do when it really doesn't matter". Which requires a hell of a lot of judgement to know when it doesn't.
Installing life-critical parts of shoddy engineering into a vital system of your airplane is a good example of when things do matter.
> The Cozy Mark IV is a 4-seat, single engine, homebuilt light aircraft [...] The aircraft is built from plans using basic raw materials. It is not a kit aircraft
You could scarcely get more DIY than this aircraft. Home-built, and not even from a kit - the builder gets to lay up every part in glass fibre themselves, by hand. And this guy had been flying it for 26 years.
It sounds like the guy was sold a part 3D printed in the wrong plastic, and it melted. He thought it was ABS, but it melted at the temperatures PLA melts at. If your engine air inlet is made of plastic that melts at 54°C (130°F) you're going to have a bad time.
It's easy to imagine how a chaotic 3D printing business might have run off a test part in a cheaper black plastic, then a confused worker could have stored the test part in with the other 'identical' parts in a different black plastic.
The 'serious' aerospace industry avoids this with lots of paperwork and procedure; when an airline maintains an airbus plane, they use only airbus-approved parts from airbus-approved sources with a paperwork trail confirming they were inspected for being-the-right-material using an approved procedure. I don't know if the home-built aircraft community would be eager to adopt those practices, though.
> That should be so obvious that I wonder if it was DIY by the pilot.
I don't know how the regulatory environment is in the UK for experimental craft (this is considered to be "experimental" category in the US and Canada), but yes, the idea behind an experimental is that everything is DIY.
I have an experimental, and I can do close to anything I want. What I can't do is complain when my plane crashes because I installed a part that isn't fit for duty. I, as the owner and operator, am the one that signs off on the airworthiness of the plane.
E.G. If I install a Cessna part on my plane, and that is the cause of a crash, that is my fault from the point of view of the FAA.
There may be legal considerations outside of airworthiness and flight rules, but as far as the FAA is concerned (or would be if this had happened in the US), the manufacturer of a part is off the hook once the thing is installed on an experimental.
>> This part could have likely been fine if it used a different material such as Ultem.
Maybe, but FDM printed parts are still much weaker than molded parts. We tried printing some coolant pump housings once during development. They worked fine until the pressure went up and then layers separated and someone got to clean the lab. At least an air intake is gonna have negative pressure which might help hold the layers together.
but it didn't fail because of stress. It failed exactly because it was made from wrong material. If the exact same part was injection molded from the same material it would melt too
It’s also a validation failure as well, because somebody assumed that the 3d-printed part could work as intended without validating it under various use-cases and situations.
Looks like they would like to make the early flight mistakes themselves instead of following air worthiness guidelines.
Just because a part has the shape of an engineered part does not make it compatible, strong, safe, and fit for purpose. This part could have likely been fine if it used a different material such as Ultem.