A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

https://www.bbc.com/news/articles/c1w932vqye0o

by toss1 • 8 months ago

250 208 8 months ago

CarVac6• 8 months ago

I wonder what material it was printed with.

edit: It was ABS-CF, which shouldn't be used under stress long-term in higher temperatures than maybe 65-70°C, or lower depending on the blend.

gostsamo• 8 months ago

The Cozy Mk IV light aircraft was destroyed after its plastic air induction elbow, bought at an air show in North America, collapsed.

the_mitsuhiko• 8 months ago

CF-ABS

An alternative construction method for the air induction elbow, shown in the Cozy Mk IV plans, is a lamination of four layers of bi-directional glassfibre cloth with epoxy resin. The epoxy resin specified for the laminate has a glass transition temperature of 84°C, after the finished part has been post-cured. The aircraft owner stated that as the glass transition temperature listed for the CF-ABS material was higher than the epoxy resin, he was satisfied the component was fit for use in this application when it was installed

https://assets.publishing.service.gov.uk/media/69297a4e345e3...

ohazi2• 8 months ago

What a misunderstanding -- glass transition temperature means different things for thermoplastics (i.e. anything that comes out of an FDM printer like the CF-ABS in question) and for thermosetting resins like epoxy that actually undergo molecular cross-linking during the curing phase. Thermoplastics will get soft and can deform without limit, while thermosets get rubbery but still more or less hold their formed shape.

buildbot• 8 months ago

I think an extended quote shows that this was a really bad call:

“ The aircraft owner stated that as the glass transition temperature listed for the CF-ABS material was higher than the epoxy resin, he was satisfied the component was fit for use in this application when it was installed. A review of the design of the laminated induction elbow in the Cozy Mk IV plans showed that it featured a section of thin-walled aluminium tube at the inlet end of the elbow, where the air filter is attached. The aluminium tube provides a degree of temperature-insensitive structural support for the inlet end of the elbow. The 3D-printed induction elbow on G-BYLZ did not include a similar section of aluminium tube at the inlet end. Tests and research Two samples from the air induction elbow were subjected to testing, using a heat-flux differential scanning calorimeter, to determine their glass transition temperature. The measured glass transition temperature for the first sample was 52.8°C, and 54.0°C for the second sample.“

jandrese• 8 months ago

The epoxy resin specified for the laminate has a glass transition temperature of 84°C

This seems very low for the kinds of epoxy I've used. I wonder if the manufacturer specs are highly conservative? Or maybe the material has a shortened lifespan with even moderate temperatures?

I was thinking about the ABS in the article and wondering if I would have made the same mistake. Close to every car manufactured today has plastic intakes, usually bolted right on top of the engine. The incoming air should help keep it cool, especially on aircraft. Maybe it was the radiant heat from a nearby cylinder that melted it?

bluerooibos• 8 months ago

I wonder who installed it. Was the pilot home 3D printing mods for their plane? And is that even allowed? Super concerning if there was a company behind the installation.

I'd think any semi competent engineer would know better.

Edit: from the report - "A modification application was made to the LAA in 2019, by the aircraft owner2 , to replace the engine’s throttle body fuel injector with a mechanical fuel injection system. This system consisted of a fuel controller, high-pressure engine-driven fuel pump, electric auxiliary fuel pump, fuel flow transducer and associated fuel hoses, filters and fittings. Following flight testing, the modified fuel system was approved by the LAA in 2022. The modified fuel injection system had accumulated 37 hours in service when the accident occurred."

So the pilot himself and the LAA were incompetent. LAA is an association for amateur pilots though so I'm not sure what level of rigour they "approve" things with.

Zak• 8 months ago

Nearly anything is allowed for experimental amateur-built aircraft like the one in this incident. Unapproved modifications to certified aircraft are forbidden in most parts of the world.

proee• 8 months ago

The plane is an experimental class, so I doubt they have to follow a lot of regulations.

duskwuff• 8 months ago

In addition to what other users have mentioned, the airplane changed hands in August 2024, after the modifications were made.

buildsjets2• 8 months ago

The LAA classified the proposed modification pf the overall fuel system as minor based on the owner’s description of it, and approved it on that basis. But the owner lied and did not disclose the fact that the induction elbow was modified at all or that it was 3D printed. The report does not discuss any required inspection by a person authorized by the LAA prior to returning the aircraft to service. So it seems like the LAA modification process is a trust-don’t-verify policy.

MBCook2• 8 months ago

Given what it was would it have been under actual stress?

Certainly seems questionable to use any 3-D printed plastic material for exhaust. That’s absolutely going to be too hot.

CarVac6• 8 months ago

It was an intake manifold, so it's continuously under suction. At the temperatures in an engine bay the plastic probably gradually creeped to a point where the restriction increased the suction and suddenly it collapses completely.

brovonov4• 8 months ago

Lower, according to the report

"Two samples from the air induction elbow were subjected to testing, using a heat-flux differential scanning calorimeter, to determine their glass transition temperature. The measured glass transition temperature for the first sample was 52.8°C, and 54.0°C for the second sample"

Yeah, they might have used ABS-CF filament, but unless they got it from a good brand that uses good resin and proper printing parameters, the actual Tg will be lower, plus the stress from the vibration/load could have made the part fail if it was not for the heat later in flight.

CarVac6• 8 months ago

Some manufacturers fudge the Tg.

Polymaker Polylite ABS has a claimed Tg of 101°C but the HDT curve clearly shows it starting to lose strength at 50°C, for example.

zuppy• 8 months ago

by the glass transition temperature, i'm willing to bet it was printed with pla (probably pla-cf).

rupellohn• 8 months ago

Full report here: https://assets.publishing.service.gov.uk/media/69297a4e345e3...

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.

An alternative construction method for the air induction elbow, shown in the Cozy Mk IV plans, is a lamination of four layers of bi-directional glassfibre cloth with epoxy resin. The epoxy resin specified for the laminate has a glass transition temperature of 84°C, after the finished part has been post-cured. The aircraft owner stated that as the glass transition temperature listed for the CF-ABS material was higher than the epoxy resin, he was satisfied the component was fit for use in this application when it was installed.

A review of the design of the laminated induction elbow in the Cozy Mk IV plans showed that it featured a section of thin-walled aluminium tube at the inlet end of the elbow, where the air filter is attached. The aluminium tube provides a degree of temperature-insensitive structural support for the inlet end of the elbow. The 3D-printed induction elbow on G-BYLZ did not include a similar section of aluminium tube at the inlet end.

teamonkey• 8 months ago

The actual report[1] holds the answer to the question you’re asking.

CF-ABS (or so claimed)

[1] https://www.gov.uk/aaib-reports/aaib-investigation-to-cozy-m...

ComputerGuru5• 8 months ago

With a melting temperature that jist happens to be the same as PLA.

They should sue the seller.

ohazi2• 8 months ago

Actual report: https://aviation-safety.net/wikibase/487013

Material was CF-ABS

shmeeed4• 8 months ago

Except that it wasn't, it's just what "the owner understood from the vendor". But the AAIB measured the Tg of material samples to be about 53 °C, which is very low and strongly suggests it being PLA or PLA-CF.

I wonder if he was erroneously sold a demonstrator part?

jacquesm12• 8 months ago

Looks like either CF loaded ABS or PLA, the difference is super hard to tell visually but given that they determined that particular temp my bet would be PLA because even PETG would be higher.

phkahler2• 8 months ago

> Material was CF-ABS

With a glass transition temp of 105C.

And yet "Two samples from the air induction elbow were subjected to testing, using a heat-flux differential scanning calorimeter, to determine their glass transition temperature. The measured glass transition temperature for the first sample was 52.8°C, and 54.0°C for the second sample."

ComputerGuru5• 8 months ago

Which is not coincidentally roughly the Tg of PLA.

o11c• 8 months ago

At a glance, that looks like worse than merely the negligence of using a new technology.

The whole point of 3D printing is that the material is moldable when hot but rigid when it cools. And people really should be aware that engines get hot.

lazide4• 8 months ago

Bought it at a get-together.

Like gunshows, it’s a magnet for bad ideas.

CarVac6• 8 months ago

I think the main issue is that many filament manufacturers mislead or outright lie about their filament capabilities.

hatsunearu3• 8 months ago

Apparently they thought it's ok because the published glass transition temp is higher than the epoxy used for fiberglass construction

nyeah• 8 months ago

I think there's some nuance missing here. "Hot" is a scale, not just a true/false check.

constantcrying3• 8 months ago

The whole point of 3D printing is that the material is moldable when hot but rigid when it cools.

Which means what exactly? Aluminum will go soft under high temperatures as well, yet this part would not have failed if it was made out of aluminum.

The failure is not the material, the failure is someone neglecting the operating conditions or material properties when choosing materials.

This exact part could have also been milled out of some plastic and would have failed the same way. The method to produce that part is only relevant in so far it is open to more people.

aidenn02• 8 months ago

Looks like the part was advertised as ABS-CF, but may have actually been PLA-CF, which makes a big difference.

There are plenty of even higher temperature materials that can be 3d-printed. PAHT-CF is fine at fairly high temperatures (the nozzle temperature needs to be over 260C), and SLS printers can print things like aluminum.

cmiles8• 8 months ago

This might be Darwin Award eligible!

shagie2• 8 months ago

The sole occupant was taken to hospital with minor injuries.

mdni007• 8 months ago

3D printing parts is FAA approved?

petcat• 8 months ago

Crash occurred in UK

stetrain• 8 months ago

I'm not sure Gloucestershire is under FAA jurisdiction.

elicash2• 8 months ago

It was purchased at a U.S. airshow

einpoklum2• 8 months ago

You may want to ask about the LAA: Light Aircraft Association.

gpm5• 8 months ago

Yes. I mean not this one, but the FAA has definitely approved 3D printed parts. SpaceX's raptor rocket engines, for instance.

rurban• 8 months ago

Lots of F1 parts are 3D printed, as well as many satellite rocket parts still flying. You just need the proper materials.

constantcrying3• 8 months ago

Some of the most advanced aircraft engines for commercial airliners contain 3D printed parts: https://www.cfmaeroengines.com/leap

The FAA denying approval to parts based on how it was manufactured and not how it performed under testing would be totally ridiculous.

dghlsakjg6• 8 months ago

This occured in the UK, so not really relevant to the FAA.

In the US though, yes, the FAA would not have a problem with this. This plane would be registered as experimental, meaning you can install unapproved parts. It does have to be inspected, but that can be done by the builder (not the designer, just the guy who built that particular example), or an airplane mechanic.

I know quite a few experimentals with 3d printed parts (including my own). I don't know any where they are installed in a place where failure would result in a crash. Typically I see them used as convenience stuff, in my case I am using a 3d printed catch to hold my upward opening door while I load the plane. If it breaks in flight, I wouldn't even know. If it breaks on the ground, the door will close.

hatsunearu3• 8 months ago

Is this a Part 103 Ultralight?

Also it's insane that they used a bolted joint with plastics on a critical place, the plastic will creep under the clamp load and will lose clamp force.

bri3d• 8 months ago

Is this a Part 103 Ultralight?

Well, no, it's in the UK. It also has a gross weight of around 2000lbs, so it's probably not subject to any of the relaxed regulations anywhere, although I don't know how the UK homebuilt rules work these days.

senectus1• 8 months ago

I'm astounded that anyone would sell, buy, or mount this to an engine or in an engine bay.

This is Darwin award nomination stuff for everyone involved.

fudged712• 8 months ago

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.

delichon• 8 months ago

blame ... the negligence of the company that created and sold this part

That should be so obvious that I wonder if it was DIY by the pilot.

ElijahLynn• 8 months ago

The Cozy Mk IV light aircraft was destroyed after its plastic air induction elbow, bought at an air show in North America, collapsed.

michaelt2• 8 months ago

https://en.wikipedia.org/wiki/Cozy_MK_IV

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.

dghlsakjg6• 8 months ago

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.

elicash2• 8 months ago

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.

https://assets.publishing.service.gov.uk/media/69297a4e345e3...

Isn't this simply a part that shouldn't have been allowed to be sold based on it being both faulty and also misleading?

johnnyanmac• 8 months ago

The implication was that the part took shortcuts and made something that only looked good on the surface. But couldn't stand up to deeper scrutiny.

hbrav• 8 months ago

Well how confident would you be that this part isn't exposed to temperatures above that glass transition temperature? It is installed near the engine.

engineer_22• 8 months ago

If vibe coding is shipping code that you don't understand and can't ensure it's safety,

And if this part was simply 3d scanned and printed in whatever material seemed strongest,

Then it could be an apt analogy

Treegarden• 8 months ago

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.

benatkin• 8 months ago

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".

1: https://nymag.com/intelligencer/2014/10/soylent-creator-hack...

2: https://x.com/karpathy/status/1990577951671509438

mwambua• 8 months ago

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.

TacticalCoder• 8 months ago

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.

ncr100• 8 months ago

Experimental Aircraft are less licensed than non-experimental, so this is more of a YOLO pilot.

averynicepen2• 8 months ago

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".

seemaze• 8 months ago

In the sense that production costs have undercut evaluation costs permitting a cadre of un(der)-qualified entrants to the space.

Not a new story in the progression of human endeavors; see the printing press, perspective painting, digital photography, residential construction.

fudged712• 8 months ago

I mean it in a very particular way.

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.

lambda• 8 months ago

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.

carabiner• 8 months ago

Vibe coding can make code that is suitable for production. 3d printed plastic can not be a substitute for a fiberglass-metal part.

shmeeed4• 8 months ago

It absolutely can. Not all 3D printing is kids' toys.

In the end it depends on the application. Vibe coded flight management systems, anyone?

sho_hn• 8 months ago

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.

phkahler2• 8 months ago

> 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.

PunchyHamster2• 8 months ago

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

itopaloglu83• 8 months ago

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.

owenversteeg2• 8 months ago

The part was claimed to be ABS-CF. UK AAIB tested the part and found it to have a Tg of approximately 53C. The Tg of ABS is far higher, around 100C. I suspect that the part may have been accidentally printed with PLA-CF (which has a Tg of approximately 55C.)

The original part was fiberglass/epoxy with the epoxy having a Tg of 84C.

brovonov4• 8 months ago

Plastics under load have a lower Tg.

hatsunearu3• 8 months ago

Isn't Tg a poorly defined metric? It seems like thermoplastics will lose their strength as temperature goes up and there's no abrupt transition where there's a near step-change in behavior

CarVac6• 8 months ago

Tg changes? Or do you mean they deflect sooner under more load?

Kirby64• 8 months ago

Tg does not change with load.

HDT does, kind of, but that’s already covered by the load being defined for the various conditions. HDT is always defined at a specific load so it also does not change with load (since load is fixed).

boothby• 8 months ago

What's Tg?

digitalPhonix• 8 months ago

Glass transition temperature I think

emil-lp• 8 months ago

Glass transition temperature.

https://en.wikipedia.org/wiki/Glass_transition

owenversteeg2• 8 months ago

Glass-liquid transition temperature, which is approximately where plastics and other materials change from hard and relatively brittle into flexible and rubbery.

As the other comments here noted, it doesn’t exactly mean that the material is safe to use for a rigid part below that temperature, and the transition extends over a range in temperatures, but it does give you a rough idea about the behavior of a material at various temperatures.

pawelduda• 8 months ago

Sounds plausible but I guess it's something that they would've confirmed, had it been true

Or it was ABS-CF but they forgot to dry the filament /s

mberning• 8 months ago

The person that installed should have thought more carefully about it. But the person that printed it and sold it should face some legal repercussions. Totally irresponsible what they did.

einpoklum2• 8 months ago

The part was a "plastic air induction elbow", i.e. this kind of thing:

https://duckduckgo.com/?q=plastic+air+induction+elbow&ia=ima...

so, if you were thinking "who would use a 3D-printed part", remember that it may otherwise also have been made with some liquid material, but using a mold, and perhaps two parts using a mold that are joined with re-heating etc. - and now it no longer sounds so outlandish.

shagie2• 8 months ago

The picture of the collapsed one is at https://ichef.bbci.co.uk/news/1024/cpsprodpb/7fee/live/52acf...

It would be curious to know what parts and connectors it should look like are.

And that texture on the right hand side of the image doesn't exactly look like something in a healthy engine.

lemonwaterlime• 8 months ago

Taken at face value, this is engineering negligence. I've done industrial design with plastics and 3D printed parts. Regardless of the forming techniques, with plastics you still need to consider properties like minimum melting temperatures, tensile stress, and so forth. Then you must test that rigorously. This is all standard procedure. That information is in the data sheet for the material.

I did a quick search and found that many plastics are governed by ISO 11357 test standard [1]. Some of the plastics I have worked with used this standard.

A spec sheet for that material is here [2].

[1] https://www.iso.org/standard/83904.html

[2] https://um-support-files.ultimaker.com/materials/1.75mm/tds/...

ToucanLoucan• 8 months ago

Also, strictly as a combo 3D-printing and engine enthusiast: Never with a GUN to my head would I install 3D printed parts in a CAR engine, let alone in an aircraft engine. This is spectacularly poor judgement on the part of the owner.

Aeolun• 8 months ago

I wouldn’t be that absolute, but not until Boeing and Airbus use them in their aircraft on a regular basis.

PunchyHamster2• 8 months ago

Well, there are more and less important parts of the car. I wouldn't bat an eye for 3d printed dash parts or the extreme example, a cup holder, but on flip side anywhere where there is heat is potentially bad for anything 3d printed with heat that's not metal or some hard to print high temp stuff, and anywhere where mechanical robustness = safety is spot where you want something very well tested, not "I printed it and it looks light".

SoftTalker3• 8 months ago

Depends. Some older or rare cars have no source for parts. 3D printing has been a boon to keeping them operating. However you absolutely have to use appropriate materials to avoid problems or failures, and know where it isn't feasible.

cibyr• 8 months ago

I'm sure it's fine you do it properly ([1] for example). The issue here was the utter lack of engineering, not the specific manufacturing technique (although those do seem to be highly correlated, due to low-end 3D printing having become very cheap and easy).

[1] https://www.youtube.com/watch?v=rV74KhPNg1w

jacquesm12• 8 months ago

Then you are not up to speed with what the 3D printing world has to offer. You can 3D print full metal stress free parts and chances are very high that if you have flown in an airplane in the last five years that some of the parts of that plane (and I'm not talking about trim here) were made using additive processes.

Rocket engines can be 3D printed, in fact there are some engines that can only be made using that kind of technique due to internal structures.

bsder• 8 months ago

Never with a GUN to my head would I install 3D printed parts in a CAR engine, let alone in an aircraft engine.

The fabrication technology doesn't matter. The qualification process, on the other hand ...

This is the primary reason why I never got a pilot's license. I suspect I would spend far too much time making sure the maintenance was up to standard and far too little actually enjoying flying.

shmeeed4• 8 months ago

FWIW, I wouldn't hesitate to install a 3D printed air-filter housing in my car, if I had printed it myself out of e.g. PAHT or sourced it from a trusty vendor. It's not rocket science, just engineering.

theideaofcoffee• 8 months ago

And this is why (at least for the US) aviation parts have such an onerous paperwork overhead, why a seemingly cheap part like a $.50 bolt balloons to much greater. Granted this aircraft was a UK-equivalent to "experimental" in the US, where you can pretty much do anything to it, I'm of the opinion that doesn't excuse maintenance and adding fly-by-night parts that borders on negligence. Stick to a minimum standard, if not just out of shame of something that could happen.

gpm5• 8 months ago

I wonder if just including the aluminum tube that was effectively acting as a heat break would have been enough...

Really it seems like a problem of not understanding the environment, and testing (with margins) your replacement in it... 3D printing seems nearly entirely unrelated apart from enabling people to make parts.

An injection molded part, for a close more traditional analogue, would presumably have failed the same way here.

Also the glass transition temperature reported in the report is suspiciously low for ABS and the only source on the material is the owner saying the person they bought it from said... I wonder if it was just outright made out of the wrong material by accident.

lazide4• 8 months ago

The difference is, injection molds are expensive. And the type of people who can afford them tend to cover their ass better - or do slightly less insanely dumb things.

3D printing (especially using filament) allows idiots to enter entirely new areas of endeavor.

gpm5• 8 months ago

I agree, but I note that the 3d printing people are making progress in making really cheap injection molds. I wouldn't count on the difference in cost remaining prohibitive enough that only reasonably serious people can afford it for much longer.

Edit: And I hope the lesson that the safety critical people take away from this is "actual engineering work is needed for airplane components" and not "3d printed parts are scary" because sooner or later they'll run into the same issue with parts made in other ways

jacquesm12• 8 months ago

3D printing (especially using filament) allows idiots to enter entirely new areas of endeavor.

That's true for any tool.

giancarlostoro• 8 months ago

I showed this to a pilot friend of mine out of curiosity, he noted that this type of aircraft is usually kit built / home built. So the fact a part of it was 3D printed was not a total shock.

Edit:

https://en.wikipedia.org/wiki/Rutan_VariEze

https://en.wikipedia.org/wiki/Burt_Rutan

commakozzi• 8 months ago

i'm confused: if they were on final and lost power, why not just glide to the runway??

edit: nvm, i found my answer in the actual report.

segmondy• 8 months ago

It's a light aircraft, the owner probably built it and is allowed to fix it. So it's probably not a company that printed the part.

gpm5• 8 months ago

Per 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

turnsout• 8 months ago

Wow. It's called "thermoplastic" for a reason.

0_____0• 8 months ago

Hah! I've actually 3D printed a part of an intake before. Just as a prototype, to allow me to get a Keihin carb on a motorcycle that had a CV carb.

Printed it on an SLA machine though! I was concerned enough about chemical attack even then, even though it was a temporary part. Never really thought about doing it in filament.

constantcrying3• 8 months ago

Hardware engineering is hard. Especially for any safety critical component.

In this case engineering was done by someone, who either did not understand the material he was working with, or the operating conditions in which that part was deployed.

Obviously no testing or any kind of proper engineering was done to create requirements validate them and verify them.

Being able to design a 3D model and print it does not mean you are done with engineering. It is just one step in a very long chain, which is needed to produce devices which stand up to their use.

luckydata• 8 months ago

correction to the title: the plane crashed because the owner is a moron, not because he bought a 3d printed part but because he failed to ensure his provider is trustworthy and instead used a fly-by-night nobody to fit a machine that can kill him at any moment.

Absurd what people will do to save a buck.

zkmon• 8 months ago

I hope 3-D printing becomes obsolete when robots can achieve the same efficiency with using the standard construction materials. That should take away all benefits of 3-D printing over regular builds.

pennomi• 8 months ago

3D printing isn’t entirely about automation, it’s also a way to get shapes that are impossible to manufacture traditionally. Modern rocket engines almost all use 3D printing because the shapes are so highly optimized.

shmeeed4• 8 months ago

You're against additive manufacturing because you want robots to become craftsmen? That's... a pretty wild take, to put it mildly.

I'm curious, what are "standard construction materials" and "regular builds" to you? And what do you think those robots are made of?

ComputerGuru5• 8 months ago

You don’t need a robot, especially in the colloquial sense meaning humanoid. Better additive manufacturing techniques than desktop FDM printers exist, and CNCs can turn these parts out from much better materials all day.

fecal_henge• 8 months ago

I'm massively paranoid that some cable clips I printed that will sit on a circuit board will perish in the heat. Meanwhile, some idiot couldn't care less about thermal stability for flight hardware!

Ccecil2• 8 months ago

Not to be a 3d print snob but....

Aside from the failure it looks like it wasn't the best print to start with. Lots of rashing from support and curling at the edges. You can see on the flats where the support was and the outer curve of the elbow looks like it likely wasn't airtight. Appears to me to be printed with the inlet facing upwards.

Better support planning, settings and possibly orientation may have helped.

Other commenters are saying it was likely PLA-CF, which I totally agree with based on the testing, but I can't help but think there is no possible way the person printing this item did not know that. I doubt the print would have come off as good as it did when using ABS-CF settings on PLA-CF.

Big chain of poor choices.

jacquesm12• 8 months ago

I've almost made that exact same mistake (but not on a critical part). I had a bunch of identical rolls with CF loaded filament of different base materials and just looking at the filament you really couldn't tell.

Ccecil2• 8 months ago

Right...I have loaded the wrong material before.

It didn't take long before I noticed. PLA is super liquid at ABS temps :)

(Not to mention that in my case ABS bed temps would melt the bottom of the PLA)

Centigonal5• 8 months ago

It's important to note the plane is a Cozy Mk IV, which is an experimental light aircraft that is built at home out of foam and fiberglass by following instructions you get online. The design is very good, and hundreds have been flown over the last ~35 years, but Cozy pilots are the aviation equivalent of people who run Arch Linux as their daily driver; many of them are tweaking their aircraft with some frequency.

This isn't a case of an established aircraft manufacturer cutting corners on a part; it's probably some small maker who made this part out of the wrong materials. It's a little shocking that neither the maker nor the buyer of this part thought to either stick it in an oven or run it with the engine on the ground to guarantee it could hold up to the expected intake air temps. I'm glad the pilot made it out with only mild injuries.

edit: here's a fun video from a Cozy pilot in case you're curious about the plane and the people who fly them: https://www.youtube.com/watch?v=Ipqmb09wbSQ

ahepp• 8 months ago

Do we know whether the part was made out of spec, or whether the spec specified inappropriate materials?

Centigonal5• 8 months ago

The spec is fiberglass, which has better thermal resistance.

dghlsakjg6• 8 months ago

I don't know if it is the same in the UK as it is in the US, but the appeal of experimental aviation (every Cozy is experimental) is that there are no specs or requirements around parts like this.

If you want to slap 15 weed-wacker engines to a wing you made from styrofoam and call it an airplane, the FAA will not stop you.

I'm oversimplifying, a bit, but less than non-pilots might think.

In other words, the engine maker probably has some thoughts about how that piece should be made, but the FAA would have no problem with you installing it on an experimental.

michaelt2• 8 months ago

It sounds like it was something like PLA when it was supposed to be ABS.

According to https://assets.publishing.service.gov.uk/media/69297a4e345e3...

The aircraft owner [...] understood from the vendor that it was printed from CF-ABS (carbon fibre – acrylonitrile butadiene styrene) filament material, with a glass transition temperature of 105°C [...] he was satisfied the component was fit for use in this application when it was installed.
[...] Two samples from the air induction elbow were subjected to testing, [...] The measured glass transition temperature for the first sample was 52.8°C, and 54.0°C for the second sample.

I've known 3D printing folks who run off a throwaway prototype in a cheap, easy-to-print material to check for fit before printing in more difficult, expensive materials. Easy to imagine a careless manufacturer getting the PLA prototype mixed in with the ABS production parts, and selling it by mistake.

Of course, the aviation industry usually steers clear of careless manufactures....

phoronixrly3• 8 months ago

[flagged]

Centigonal5• 8 months ago

General aviation (and especially experimental light aircraft) is not a particularly safe hobby. This pilot literally put his life in the hands of a 3D printed part someone sold him at an airshow. Pilots can and do "brick" their planes as a result of "innovative" approaches to repairs, upgrades, and maintenance. Luckily, much of the time these errors are caught before the plane gets off the ground.

mort96• 8 months ago

The analogy they weren't making: "This is life critical, just like Arch Linux"

The analogy they were making: "This is a commonly home-built and heavily customized hacker aircraft, just like Arch Linux is a commonly home-built and heavily customized hacker Linux distro"

Two things can be analogous in one aspect while being disanalogous in another aspect. That doesn't make the analogy invalid.

onraglanroad• 8 months ago

Clearly you have a boring life. Dial it up a bit!

tomhow• 8 months ago

Please don't post shallow dismissals on HN. We're aiming for a higher standard of discussion here. https://news.ycombinator.com/newsguidelines.html

SoftTalker3• 8 months ago

Figured it was experimental; no A&P who cared about his future would install a 3D printed part on a certified aircraft.

soursoup• 8 months ago

Loads of commercial aircraft and jet engine parts are manufactured using additive manufacturing, or ”3D printing”

jcranmer• 8 months ago

Actually, I think all of the jet engine manufacturers these days are using 3d printers for some of their parts? Although you usually find the press releases talking about this using the term "additive manufacturing" instead. See, e.g., this press release from 2018 about a notable jet engine manufacturer using 3d printing: https://www.geaerospace.com/news/articles/manufacturing/manu...

(Although note that these are not using plastic parts, to be clear.)

ummonk• 8 months ago

A 3d printed Inconel part would be fine. 3d printed plastic is something else entirely...

abrookewood• 8 months ago

I think this needs to be added to the urban dictionary "Cozy pilots are the aviation equivalent of people who run Arch Linux as their daily driver"

genewitch• 8 months ago

Belite, a company that folded (and just renamed themselves) after a certain number of crashes of their experimental ultralights, sold my dad a plane where the AOA sensor was malfunctioning, the propeller hit the ground if there was someone in the plane, and one wing side was longer than the other. By a visible amount. My dad broke a set of propellers and they sent him a new set with 3" cut off each blade. i have those in my shed.

I'm no aerospace engineer or anything, but that plane shouldn't have been able to stay in the air.

and, lo, it didn't, the motorcycle engine used as the prime mover sputtered out at 200' AGL and since it's not a glider (and i don't even think it can glide), it crashed straight into the ground.

Fly an ultralight if you want, just be aware that people will think very poorly of you.

linsomniac• 8 months ago

Are those class 8 bolts holding a plastic (PLA? PETG?) part in place? I guess the original part would have been some sort of metal?

pfdietz• 8 months ago

I just watched a fun video of a guy bringing a 1978 Datsun 280Z up to date. He kept the existing engine but upgraded it with modern electronic ignition and computer control. As part of all that, he fabricated various parts in plastic by 3D printing, but then had the final versions made elsewhere in metal -- some by a CNC shop you send CAD files to, and one by a manual machinist in Switzerland with his own Youtube channel. The latter has to be case hardened, which the machinist did.

The 3D printed plastic parts were very useful to prove out the parts' shapes.

https://www.youtube.com/watch?v=jZ38C-M3tyk -- engine upgrade

https://www.youtube.com/watch?v=D2bxsEyYdo0 -- My Mechanics making the part

lutusp• 8 months ago

They included everything but the 3D printed material. If it was PLA, no surprise (and no excuse). Even ABS might not stand up to the temperatures at that location. I hate it when a news report tells you everything except details that might make a difference going forward.

cjbgkagh2• 8 months ago

Thankfully minor injuries.

A thermoplastic in an engine cowling is insane. It’s crazy that this was being sold the supplier should have known better, as should the buyer. 3D printing can be used to make a fiberglass or carbon fiber mold which is already a lot of the work of making the part.

It would be interesting to know what filament was used, in theory some high temp filament could be suitable but I would be nervous putting those on a car let alone a plane.

Edit: https://assets.publishing.service.gov.uk/media/69297a4e345e3...

The actual report includes the important details, ABS-CF which they thought was safe because they underestimated the glass transition temperature of epoxy fiberglass.

aidenn02• 8 months ago

Why is the 3d-printed part highlighted; upon first reading this looks like the part softened; it didn't separate on FDM boundaries. Wouldn't a similar thing have happened if it were formed in a different way, but of the same materials?

curiousObject• 8 months ago

It sounds like simply running the engine on the ground for a few hours would have been a much cheaper way to debug this issue. Safer, also.

blastersyndrome• 8 months ago

This last line is concerning:

The Light Aircraft Association (LAA) said it now intends to take safety actions in response to the accident, including a "LAA Alert" regarding the use of 3D-printed parts that will be sent to inspectors.

Does this mean that anybody using any 3d printed part in an aircraft will be subjected to this scrutiny? If I use the proper materials with a suitable printer (eg, printing PEEK with a properly specced printer), how much convincing will it take to get these governing bodies off my back?

A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat

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