[HN Gopher] Plane crashed after 3D-printed part collapsed
___________________________________________________________________
Plane crashed after 3D-printed part collapsed
Author : toss1
Score : 179 points
Date : 2025-12-04 20:56 UTC (2 hours ago)
(HTM) web link (www.bbc.com)
(TXT) w3m dump (www.bbc.com)
| CarVac wrote:
| 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 65-70degC, or lower
| depending on the blend.
| gostsamo wrote:
| > 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 wrote:
| 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 84degC, 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...
| ohazi wrote:
| 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 wrote:
| 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 52.8degC, and 54.0degC
| for the second sample."
| jandrese wrote:
| > The epoxy resin specified for the laminate has a glass
| transition temperature of 84degC
|
| 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?
| CarVac wrote:
| There are some incredibly low Tg epoxies out there, such as
| West Systems 105 where "TG onset" is 54degC and the heat
| deflection temperature is even lower.
| bluerooibos wrote:
| 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 wrote:
| 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 wrote:
| The plane is an experimental class, so I doubt they have to
| follow a lot of regulations.
| duskwuff wrote:
| In addition to what other users have mentioned, the airplane
| changed hands in August 2024, after the modifications were
| made.
| MBCook wrote:
| 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.
| CarVac wrote:
| 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.
| MBCook wrote:
| Oh the suction, I wasn't considering that. I was thinking
| of general compression or tension between the connections
| on the ends.
| brovonov wrote:
| 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 52.8degC,
| and 54.0degC 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.
| CarVac wrote:
| Some manufacturers fudge the Tg.
|
| Polymaker Polylite ABS has a claimed Tg of 101degC but the
| HDT curve clearly shows it starting to lose strength at
| 50degC, for example.
| brovonov wrote:
| Polymaker's ABS is dubious too because it is blended with
| PETG. They are coming out with a Pro version that has a
| higher Tg and requires way higher chamber temps to print
| properly.
| zuppy wrote:
| by the glass transition temperature, i'm willing to bet it
| was printed with pla (probably pla-cf).
| rupellohn wrote:
| 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 105degC.
|
| 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 84degC, 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 wrote:
| 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...
| ohazi wrote:
| Actual report: https://aviation-safety.net/wikibase/487013
|
| Material was CF-ABS
| shmeeed wrote:
| 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 degC, which is very low and strongly
| suggests it being PLA or PLA-CF.
|
| I wonder if he was erroneously sold a demonstrator part?
| jacquesm wrote:
| 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.
| phkahler wrote:
| >> 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 52.8degC, and 54.0degC for the second sample."
| o11c wrote:
| 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.
| lazide wrote:
| Bought it at a get-together.
|
| Like gunshows, it's a magnet for bad ideas.
| CarVac wrote:
| I think the main issue is that many filament manufacturers
| mislead or outright lie about their filament capabilities.
| hatsunearu wrote:
| Apparently they thought it's ok because the published glass
| transition temp is higher than the epoxy used for fiberglass
| construction
| nyeah wrote:
| I think there's some nuance missing here. "Hot" is a scale, not
| just a true/false check.
| constantcrying wrote:
| >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.
| cmiles8 wrote:
| This might be Darwin Award eligible!
| shagie wrote:
| > The sole occupant was taken to hospital with minor injuries.
| mdni007 wrote:
| 3D printing parts is FAA approved?
| petcat wrote:
| Crash occurred in UK
| stetrain wrote:
| I'm not sure Gloucestershire is under FAA jurisdiction.
| einpoklum wrote:
| You may want to ask about the LAA: Light Aircraft Association.
| gpm wrote:
| Yes. I mean not this one, but the FAA has definitely approved
| 3D printed parts. SpaceX's raptor rocket engines, for instance.
| rurban wrote:
| Lots of F1 parts are 3D printed, as well as many satellite
| rocket parts still flying. You just need the proper materials.
| constantcrying wrote:
| 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.
| hatsunearu wrote:
| 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 wrote:
| > 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.
| fudged71 wrote:
| 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 wrote:
| > 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 wrote:
| > The Cozy Mk IV light aircraft was destroyed after its
| plastic air induction elbow, bought at an air show in North
| America, collapsed.
| michaelt wrote:
| 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 54degC (130degF)
| 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.
| elicash wrote:
| 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 105degC.
|
| 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 wrote:
| 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 wrote:
| 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.
| film42 wrote:
| Installed _on_ an engine that operates at 200oC!
| plorg wrote:
| 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.
| engineer_22 wrote:
| 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 wrote:
| 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.
| serf wrote:
| >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.
| Ntrails wrote:
| 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
| cortesoft wrote:
| This is more like adding a third party dependency to your
| project without vetting it.
| saltcured wrote:
| 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.
| benatkin wrote:
| 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
| seg_lol wrote:
| He is gonna get slopabetes!
| mwambua wrote:
| In the report they tested samples of the part and found that
| they actually had glass transition temperatures of 52.8degC,
| and 54.0degC... so sounds like the owner fell victim to false
| advertising.
| plorg wrote:
| And in fact the owner was not the person who installed the
| part!
| ncr100 wrote:
| Experimental Aircraft are less licensed than non-
| experimental, so this is more of a YOLO pilot.
| averynicepen wrote:
| 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".
| phoronixrly wrote:
| 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?
| defrost wrote:
| 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)
| seemaze wrote:
| 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.
| carabiner wrote:
| Vibe coding _can_ make code that is suitable for production. 3d
| printed plastic _can not_ be a substitute for a fiberglass-
| metal part.
| sho_hn wrote:
| 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.
| phkahler wrote:
| >> 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.
| PunchyHamster wrote:
| 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 wrote:
| 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.
| owenversteeg wrote:
| 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.
| brovonov wrote:
| Plastics under load have a lower Tg.
| hatsunearu wrote:
| 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
| brovonov wrote:
| It kind of is, a better metric is HDT (Heat Deflection
| Temperature), and it is based on curve usually load over
| temp.
| gpm wrote:
| And a datasheet for _a_ (not necessarily the same) CF-ABS
| filament claims a HDT at 1.82 MPa of 93C: https://um-
| support-files.ultimaker.com/materials/1.75mm/tds/...
|
| Something funny is going on with this material given the
| report is saying they measured a glass transition
| temperature of ~50C.
| ggreer wrote:
| I doubt there is any form of ABS filament with such a low
| glass transition temperature. As the original poster
| said, it was probably PLA.
|
| I find it odd that the report didn't name the
| manufacturer of the part, and that the part was not
| listed on the LAA modification form. There can't be many
| people selling such parts at airshows, so you'd think the
| investigators would have been able to find out who made
| it.
|
| Now I wonder if the previous owner (who installed the new
| fuel system) printed the part himself, then claimed he
| bought it overseas to avoid blame.
| CarVac wrote:
| Tg changes? Or do you mean they deflect sooner under more
| load?
| nomel wrote:
| Maybe "load" includes the heat that comes from the changes
| forces from the vibrations?
| nomel wrote:
| Maybe "load" includes the heat that comes from the changes
| forces from the vibrations? But even then, that would be
| additional heat sources, rather than a change in the
| temperature where it happens.
| Kirby64 wrote:
| 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 wrote:
| What's Tg?
| digitalPhonix wrote:
| Glass transition temperature I think
| emil-lp wrote:
| Glass transition temperature.
|
| https://en.wikipedia.org/wiki/Glass_transition
| owenversteeg wrote:
| 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 wrote:
| 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 wrote:
| 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.
| einpoklum wrote:
| 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.
| shagie wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| I wouldn't be that absolute, but not until Boeing and Airbus
| use them in their aircraft on a regular basis.
| geocrasher wrote:
| Yes but are they printed with PLA or PETG, or even ABS? Or
| are they using material designed exactly for their use
| case, and tested thoroughly before being _certified_ for
| flight?
|
| Or do they get their parts from some vendor at a swap meet
| who spends most of his time fiddling with his Ender 3?
| jacquesm wrote:
| Neither of those is suitable for this application. Ultem
| or PEEK. Anything else would be a very bad idea, and even
| for those two you would want to do a lot of testing.
| PunchyHamster wrote:
| 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".
| SoftTalker wrote:
| 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 wrote:
| 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
| jacquesm wrote:
| 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.
| theideaofcoffee wrote:
| 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.
| gpm wrote:
| 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.
| lazide wrote:
| 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.
| gpm wrote:
| 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
| jacquesm wrote:
| > 3D printing (especially using filament) allows idiots to
| enter entirely new areas of endeavor.
|
| That's true for any tool.
| giancarlostoro wrote:
| 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 wrote:
| 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 wrote:
| 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.
| gpm wrote:
| 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 wrote:
| Wow. It's called "thermoplastic" for a reason.
| 0_____0 wrote:
| 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.
| constantcrying wrote:
| 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 wrote:
| 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 wrote:
| 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 wrote:
| 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.
| shmeeed wrote:
| 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?
| fecal_henge wrote:
| 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!
| Ccecil wrote:
| 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.
| jacquesm wrote:
| 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.
| Centigonal wrote:
| 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 can 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 wrote:
| Do we know whether the part was made out of spec, or whether
| the spec specified inappropriate materials?
| Centigonal wrote:
| The spec is fiberglass, which has better thermal resistance.
| jacquesm wrote:
| But not _that_ much better compared the better filaments
| out there. Fair chance it was printed out of PLA, ABS or
| PETG, by the shade of the part it looks like it was CF
| loaded filament.
|
| A better choice would have been PEEK. But even then, I
| would have done a lot of on-the-ground testing before
| trusting my life to a part from the printer.
| Centigonal wrote:
| 100% -- the original design for the Cozy is from the
| early 90s, before 3D printing became popular, and this
| part seems like a good candidate for 3D printing. It just
| seems like the maker chose the wrong materials and didn't
| test it adequately.
| phoronixrly wrote:
| With the tiny difference that my life has never depended on my
| Linux booting... Bad comparison.
| Centigonal wrote:
| 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.
| phoronixrly wrote:
| Guy, the person who bet his life on a part with
| questionable quality is a moron. People who choose an OS
| are _not betting their life_ on their OS booting up. Do you
| not grasp the difference in stakes?
| Centigonal wrote:
| mort96 explained my analogy better than I could.
| Obviously your OS and your plane are not equally risky
| choices. Regardless, there exist communities of people
| who like to heavily customize either of those things.
| crumpled wrote:
| I don't think anyone is struggling with grasping the
| difference in stakes. The stakes are different, the size
| and shape are different, there are a lot of things
| different.
|
| You don't make analogies out of things that are the same,
| that's one of the hallmarks of an analogy.
| mort96 wrote:
| 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 wrote:
| Clearly you have a boring life. Dial it up a bit!
| SoftTalker wrote:
| Figured it was experimental; no A&P who cared about his future
| would install a 3D printed part on a certified aircraft.
| soursoup wrote:
| Loads of commercial aircraft and jet engine parts are
| manufactured using additive manufacturing, or "3D printing"
| kaonwarb wrote:
| Yes... but more often something like laser-sintered metal
| printing, which is not going to melt when hot.
| jcranmer wrote:
| 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/n
| ews/articles/manufacturing/manu...
|
| (Although note that these are not using plastic parts, to be
| clear.)
| genewitch wrote:
| 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.
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