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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

#111

Post by phoronixrly »

averynicepen wrote: post #105
elicash wrote: post #57

Earlier quoted context omitted.

In what way is this like vibe-coding -- or do you just mean both are bad? According to the report: > The aircraft owner who installed the modified fuel system stated that the 3D-printed induction elbow was purchased in the USA at an airshow, and he understood from the vendor that it was printed from CF-ABS (carbon fibre – acrylonitrile butadiene styrene) filament material, with a glass transition temperature3 of 105°…

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 func…

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?

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

#112

Post by MBCook »

CarVac wrote: post #14
MBCook wrote: post #12

Earlier quoted context omitted.

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.

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.

Oh the suction, I wasn’t considering that. I was thinking of general compression or tension between the connections on the ends.

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

#113

Post by PunchyHamster »

ToucanLoucan wrote: post #85
lemonwaterlime wrote: post #40

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…

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.

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".

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

#114

Post by itopaloglu83 »

fudged71 wrote: post #27

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.

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.

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

#115

Post by SoftTalker »

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.

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

#116

Post by shmeeed »

ohazi wrote: post #4

Actual report: https://aviation-safety.net/wikibase/487013 Material was CF-ABS

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

I wonder if he was erroneously sold a demonstrator part?

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

#117

Post by phkahler »

ohazi wrote: post #4

Actual report: https://aviation-safety.net/wikibase/487013 Material was CF-ABS

>> 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."

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

#118

Post by mort96 »

phoronixrly wrote: post #107
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…

[flagged]

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.

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

#119

Post by onraglanroad »

phoronixrly wrote: post #107
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…

[flagged]

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

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

#120

Post by jacquesm »

Centigonal wrote: post #106
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?

The spec is fiberglass, which has better thermal resistance.

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.

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