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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 instruct
by Centigonal 10mo 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 https://www.youtube.com/watch?v=Ipqmb09wbSQ
- ahepp 10mo agoDo we know whether the part was made out of spec, or whether the spec specified inappropriate materials?
- Centigonal 10mo agoThe spec is fiberglass, which has better thermal resistance.
- jacquesm 10mo 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 10mo 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.
- jacquesm 10mo agoIt's a candidate, but it is definitely not a run race, temps under the engine covers of a plane can get surprisingly high (surprising because you'd think you have plenty of airflow half a meter behind a pocket hurricane). I'm not sure if high temp filaments would be the solution here, but they'd be better candidates. It would need some very thorough testing before trusting your life (or in this case: someone else's) to that kind of solution.
- ComputerGuru 10mo agoThere’s a massive difference between the thermal properties of the materials you listed.
- jacquesm 10mo agoYes, that's why I listed them. And even then: none of those first three are (safely) usable for this application. PEEK or ULTEM or something better than that.
- ComputerGuru 10mo agoI absolutely agree. At the same time, I’m just flabbergasted that someone really thought they’d pass off PLA crap for such a purpose, it literally loses shape in sunlight. PETG isn’t going to cut it and I wouldn’t want to be on a plane with PETG in a heat-sensitive part, but that would still have been less ridiculous given that a) it’s significantly better than PLA in this regard, and b) unlike PEI and PEEK, it can be printed with ease on just about any FDM.
- dghlsakjg 10mo agoI 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.
- scarier 10mo agoMy understanding of the UK CAA is that it isn’t as liberal as the US FAA when it comes to amateur-built experimental aircraft airworthiness. I would still be surprised if a 3d-printed intake manifold on a homebuilt passed an airworthiness inspection in the US without a number of detailed questions being answered to the satisfaction of the airworthiness representative.
- deleted 10mo ago[deleted]
- michaelt 10mo agoIt sounds like it was something like PLA when it was supposed to be ABS. According to 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 [...] 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....
- Ancapistani 10mo agoThat's... absurd. ABS is a terrible choice for anything in an engine bay - ABS breaks down over time when in contact with oils. I've used PA6-CF for similar purposes in the past. Obviously not for aircraft, though.
- poulpy123 10mo agoEven in ABS I would not use something 3D printed on a consumer machine as a critical part of an airplane.
- Doxin 10mo agoYou'd be very hard pressed to confuse PLA with carbon fiber reinforced ABS. The latter has a definite surface texture that's hard to get confused with that of PLA.
- phoronixrly 10mo ago[flagged]
- Centigonal 10mo agoGeneral 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 10mo agoGuy, 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 10mo agomort96 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 10mo agoI 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 10mo agoThe 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.
- SoftTalker 10mo agoFigured it was experimental; no A&P who cared about his future would install a 3D printed part on a certified aircraft.
- soursoup 10mo agoLoads of commercial aircraft and jet engine parts are manufactured using additive manufacturing, or ”3D printing”
- jcranmer 10mo agoActually, 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/manufacturing-milestone-30000-additive-fuel-nozzles https://www.geaerospace.com/news/articles/manufacturing/manu... (Although note that these are not using plastic parts, to be clear.)
- Aurornis 10mo agoManufacturers who use 3D printing use specialized 3D printers, not the same thing that hobbyists use. They also handle all of the testing of parts to ensure they meet the design spec and they have the equipment to validate each printed part to ensure it doesn't have any major defects.
- abrookewood 10mo agoI 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"