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

bbc.com

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

#211

Post by jacquesm »

ComputerGuru wrote: post #201
jacquesm wrote: post #162

Earlier quoted context omitted.

Yes, 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.

I 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 b…

Whoever sold that part deserves to be sued. I'm not from the 'sue happy' department but this was extremely irresponsible and unless the swap for PLA was accidental (which can easily be proven, they must have sold more than just one of these). At a minimum they should recall each and every one of these they have made and on top of that they should review all of the other parts that person has made for similar issues.

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

#212

Post by poulpy123 »

michaelt wrote: post #208
ahepp wrote: post #103

Earlier quoted context omitted.

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

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 applicatio…

Even in ABS I would not use something 3D printed on a consumer machine as a critical part of an airplane.

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

#213

Post by jacquesm »

Centigonal wrote: post #130
jacquesm wrote: post #120

Earlier quoted context omitted.

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.

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.

It'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.

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

#214

Post by 2muchcoffeeman »

Ancapistani wrote: post #209
2muchcoffeeman wrote: post #180

Earlier quoted context omitted.

You can see the layer lines in the part. WTF? I don’t build aircraft parts. But I sure as hell wont use thermoplastics in this situation. I don’t even 3D print parts for mildly hot environments where failure is just annoyance. Whoever built this should be charged.

I've printed and used intake manifolds for (automotive) engines in the past, without issue. Obviously that's not the same stakes as an aircraft, but I don't see why it wouldn't be possible to do safely.

I’m not necessarily saying it can’t be done. But these are plastics that fail under heat. I’d test part for non critical applications and I’m just a nobody amateur.

These guys are messing with planes and don’t test enough? Is there an explanation these people aren’t just incompetent?

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

#215

Post by ummonk »

SoftTalker wrote: post #115
Centigonal wrote: post #102

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. Th…

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

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

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

#216

Post by toss1 »

jacquesm wrote: post #127
ToucanLoucan wrote: post #85

Earlier quoted context omitted.

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.

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 kin…

Yes, real parts CAN be 3D printed and even used successfully.

The printing is the easy part.

The extensive testing and validation that it will actually work as intended and in your situation is the hard part.

Skip that hard part, especially for anything that flies, and you are risking lives, both those in the air and on the ground.

Seriously, just because the specs on the label say X and other docs say the running temperature is Y, does NOT mean it will work. Take the measurements in your situation, test the thing extensively on the ground.

Then, maybe, it'll be worth flying. Or, you'll be there after some hours of testing saying: "good thing I didn't try to fly with this", and still have a usable aircraft.

Edit: missing words, clarity.

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

#217

Post by Ancapistani »

2muchcoffeeman wrote: post #214
Ancapistani wrote: post #209

Earlier quoted context omitted.

I've printed and used intake manifolds for (automotive) engines in the past, without issue. Obviously that's not the same stakes as an aircraft, but I don't see why it wouldn't be possible to do safely.

I’m not necessarily saying it can’t be done. But these are plastics that fail under heat. I’d test part for non critical applications and I’m just a nobody amateur. These guys are messing with planes and don’t test enough? Is there an explanation these people aren’t just incompetent?

Not that I can think of, honestly. I'd be extremely hesitant to use a part I printed on an aircraft. If I had to, I'd make very sure to test multiple copies to destruction.

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

#218

Post by thijson »

jcranmer wrote: post #144
SoftTalker wrote: post #115

Earlier quoted context omitted.

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

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 no…

I think spacex uses it too, that's probably key to their engine becoming smaller and smaller over time.

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

#219

Post by bombela »

2muchcoffeeman wrote: post #214
Ancapistani wrote: post #209

Earlier quoted context omitted.

I've printed and used intake manifolds for (automotive) engines in the past, without issue. Obviously that's not the same stakes as an aircraft, but I don't see why it wouldn't be possible to do safely.

I’m not necessarily saying it can’t be done. But these are plastics that fail under heat. I’d test part for non critical applications and I’m just a nobody amateur. These guys are messing with planes and don’t test enough? Is there an explanation these people aren’t just incompetent?

> But these are plastics that fail under heat.

All materials ultimately succomb when exposed long enough at some high enough temperature.

What is the temperature range to match here?

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

#220

Post by jacquesm »

toss1 wrote: post #216
jacquesm wrote: post #127

Earlier quoted context omitted.

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 kin…

Yes, real parts CAN be 3D printed and even used successfully. The printing is the easy part. The extensive testing and validation that it will actually work as intended and in your situation is the hard part. Skip that hard part, especially for anything that flies, and you are risking lives, both those in the air and on the ground. Seriously, just because the specs on the label say X and other docs say the running te…

Indeed, I think I already covered that in an older comment and didn't want to repeat the same info: https://news.ycombinator.com/item?id=46159905
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