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A Cozy Mk IV light aircraft crashed after 3D-printed part was weakened by heat
- CarVac 11mo agoI 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.
- deleted 11mo ago[deleted]
- gostsamo 11mo 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 11mo agoCF-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/69297a4e345e31ab14ecf6e9/Cozy_Mk_IV_G-BYLZ_01-26.pdf https://assets.publishing.service.gov.uk/media/69297a4e345e3...
- ohazi 11mo agoWhat 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 11mo agoI 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.“
- deleted 11mo ago[deleted]
- jandrese 11mo 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?
- CarVac 11mo agoThere are some incredibly low Tg epoxies out there, such as West Systems 105 where "TG onset" is 54°C and the heat deflection temperature is even lower.
- bluerooibos 11mo agoI 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 11mo agoNearly 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 11mo agoThe plane is an experimental class, so I doubt they have to follow a lot of regulations.
- duskwuff 11mo agoIn addition to what other users have mentioned, the airplane changed hands in August 2024, after the modifications were made.
- buildsjets 11mo agoThe 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.
- MBCook 11mo agoGiven 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 11mo agoIt 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 11mo agoOh the suction, I wasn’t considering that. I was thinking of general compression or tension between the connections on the ends.
- brovonov 11mo agoLower, 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.
- CarVac 11mo agoSome 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.
- brovonov 11mo agoPolymaker'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 11mo agoby the glass transition temperature, i'm willing to bet it was printed with pla (probably pla-cf).
- rupellohn 11mo agoFull report here: https://assets.publishing.service.gov.uk/media/69297a4e345e31ab14ecf6e9/Cozy_Mk_IV_G-BYLZ_01-26.pdf 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 11mo agoThe 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-mk-iv-g-bylz https://www.gov.uk/aaib-reports/aaib-investigation-to-cozy-m...
- ComputerGuru 11mo agoWith a melting temperature that jist happens to be the same as PLA. They should sue the seller.
- ohazi 11mo agoActual report: https://aviation-safety.net/wikibase/487013 https://aviation-safety.net/wikibase/487013 Material was CF-ABS
- deleted 11mo ago[deleted]
- shmeeed 11mo agoExcept 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?
- jacquesm 11mo agoLooks 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 11mo 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."
- ComputerGuru 11mo agoWhich is not coincidentally roughly the Tg of PLA.
- o11c 11mo agoAt 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 11mo agoBought it at a get-together. Like gunshows, it’s a magnet for bad ideas.
- CarVac 11mo agoI think the main issue is that many filament manufacturers mislead or outright lie about their filament capabilities.
- hatsunearu 11mo agoApparently they thought it's ok because the published glass transition temp is higher than the epoxy used for fiberglass construction
- onetokeoverthe 11mo ago[dead]
- nyeah 11mo agoI think there's some nuance missing here. "Hot" is a scale, not just a true/false check.
- constantcrying 11mo 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.
- 11mo ago
- cmiles8 11mo agoThis might be Darwin Award eligible!
- shagie 11mo ago> The sole occupant was taken to hospital with minor injuries.
- mdni007 11mo ago3D printing parts is FAA approved?
- petcat 11mo agoCrash occurred in UK
- stetrain 11mo agoI'm not sure Gloucestershire is under FAA jurisdiction.
- elicash 11mo agoIt was purchased at a U.S. airshow
- dghlsakjg 11mo agoThey sold an entire UK county at an airshow?
- buildsjets 11mo agoFlea markets at US airshows are not under FAA jurisdiction. I have attended said airshow for decades and occasionally buy stuff in the flea market myself. Old used scrapyard parts, next to some inventor’s homemade jet engine, next to tons of raw materials of unknown provenance, next to ginsu knives and miracle frying pans. Here’s what it looks like on video. Wow, I missed those hand grenades for only $10 each, what a bargain. https://youtu.be/kKZ8Omj5cNA?si=bMQGS3VxN6ljyW19 https://youtu.be/kKZ8Omj5cNA?si=bMQGS3VxN6ljyW19 https://www.aero-news.net/index.cfm?do=main.textpost&id=cf1c9419-80e6-4f71-aa0b-685480df763f https://www.aero-news.net/index.cfm?do=main.textpost&id=cf1c...
- einpoklum 11mo agoYou may want to ask about the LAA: Light Aircraft Association.
- gpm 11mo agoYes. I mean not this one, but the FAA has definitely approved 3D printed parts. SpaceX's raptor rocket engines, for instance.
- hatsunearu 11mo agoIs 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 11mo 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 11mo agoI'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.
- fudged71 11mo agoThis 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.
- deleted 11mo ago[deleted]
- delichon 11mo 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.
- deleted 11mo ago[deleted]
- ElijahLynn 11mo ago> The Cozy Mk IV light aircraft was destroyed after its plastic air induction elbow, bought at an air show in North America, collapsed.
- michaelt 11mo agohttps://en.wikipedia.org/wiki/Cozy_MK_IV 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.
- owenversteeg 11mo agoThe 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 11mo agoPlastics under load have a lower Tg.
- hatsunearu 11mo agoIsn'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 11mo agoIt kind of is, a better metric is HDT (Heat Deflection Temperature), and it is based on curve usually load over temp.
- gpm 11mo agoAnd 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/Method-ABS-CF/UltiMaker-Method-ABS-CF-TDS-v1.00.pdf 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 11mo agoI 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.
- mberning 11mo agoThe 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 11mo agoThe part was a "plastic air induction elbow", i.e. this kind of thing: https://duckduckgo.com/?q=plastic+air+induction+elbow&ia=images&iax=images 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 11mo agoThe picture of the collapsed one is at https://ichef.bbci.co.uk/news/1024/cpsprodpb/7fee/live/52acff30-d130-11f0-a0cc-673bf7abfc30.png.webp 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 11mo agoTaken 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 https://www.iso.org/standard/83904.html [2]: https://um-support-files.ultimaker.com/materials/1.75mm/tds/Method-ABS-CF/UltiMaker-Method-ABS-CF-TDS-v1.00.pdf https://um-support-files.ultimaker.com/materials/1.75mm/tds/...
- ToucanLoucan 11mo agoAlso, 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 11mo agoI wouldn’t be that absolute, but not until Boeing and Airbus use them in their aircraft on a regular basis.
- geocrasher 11mo agoYes 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 11mo agoNeither 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.
- theideaofcoffee 11mo agoAnd 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 11mo agoI 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 11mo agoThe 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 11mo agoI 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 11mo ago> 3D printing (especially using filament) allows idiots to enter entirely new areas of endeavor. That's true for any tool.
- lazide 11mo agoAnd when someone makes a new affordable tool that opens up making new types of things…. What happens?
- giancarlostoro 11mo agoI 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/Rutan_VariEze https://en.wikipedia.org/wiki/Burt_Rutan https://en.wikipedia.org/wiki/Burt_Rutan
- commakozzi 11mo agoi'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 11mo agoIt'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 11mo agoPer 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 11mo agoWow. It's called "thermoplastic" for a reason.
- 0_____0 11mo agoHah! 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 11mo agoHardware 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 11mo agocorrection 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 11mo agoI 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 11mo ago3D 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 11mo agoYou'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?
- ComputerGuru 11mo agoYou 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 11mo agoI'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!
- deposittag 11mo ago[dead]
- Ccecil 11mo agoNot 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 11mo agoI'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.
- Ccecil 11mo agoRight...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)
- jacquesm 11mo agoOh that could have been quite messy if you had done that unattended. I've gone through a couple of thousand kg of filament in the last year and I've had some 'interesting' failures.
- Centigonal 11mo agoIt'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 https://www.youtube.com/watch?v=Ipqmb09wbSQ
- ahepp 11mo agoDo we know whether the part was made out of spec, or whether the spec specified inappropriate materials?
- Centigonal 11mo agoThe spec is fiberglass, which has better thermal resistance.
- jacquesm 11mo agoBut 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 11mo ago100% -- 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.
- genewitch 11mo agoBelite, 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 11mo agoAre 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 11mo agoI 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 https://www.youtube.com/watch?v=jZ38C-M3tyk -- engine upgrade https://www.youtube.com/watch?v=D2bxsEyYdo0 https://www.youtube.com/watch?v=D2bxsEyYdo0 -- My Mechanics making the part
- lutusp 11mo agoThey 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.
- cjbgkagh 11mo agoThankfully 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/69297a4e345e31ab14ecf6e9/Cozy_Mk_IV_G-BYLZ_01-26.pdf 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.
- aidenn0 11mo agoWhy 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?
- deleted 11mo ago[deleted]
- curiousObject 11mo agoIt 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 11mo agoThis 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?