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 not using plastic parts, to be clear.)

Manufacturers 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.

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.

> Whoever built this should be charged.

This is an uncertified experimental aircraft. At least in the US, it is up to the operator of an experimental to ensure that parts are fit for purpose.

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.

> 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?

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

I'm not a material scientist, but I don't believe that to be true. Metals don't to my knowledge; they suffer oxidation, which is allayed by the presence of oil.

If you mean plastics in particular, then PEEK would be ideal to my knowledge - it's suitable for immersion in gasoline and similar solvents, and I've used it in the past for a fuel pump mounting bracket that sits inside the fuel tank of a (gasoline) vehicle. I checked it after a year and it doesn't seem to be any worse for wear.

It's just a huge pain to print!

> What is the temperature range to match here?

I'm not sure, and likely couldn't be sure without a fair amount of research. If I had to print this for a plane, I'd want to do that and measure temperature in use and under high load and destructively test several drafts to ensure performance.

From what I've seen in this instance though, the failed part showed a Tg (glass transition temperature) of 55ºC - basically exactly that of PLA-CF. The pilot believed it was ABS-CF, which has a Tg of ~100ºC. If we assume that 100ºC was at least higher than the expected operating temperature, PEEK (Tg: 143ºC) would have given a ~50% safety margin.

Yes, implicit was that it was an uncertified part 3D-printed by "someone" who sold it at an airshow. Obviously a certified part from the manufacturer is a different story.

The 3D printing isn't the actual problem, as you note.

It's note the "3D printed" aspect of the part that's driving the failure, it's that it's made out of thermoplastic. An injection molded part in this situation[1] would likely have failed in the same way.

[1] It's not clear what the source of the heat was or where this was in the motor enclosure. But yeah, one needs to be careful with structural plastic near running engines!

Thermoplastic is the problem here. There are plenty of thermoset and other kinds of plastics that handle heat well and don’t soften with heat in normal ranges. 3d printed thermoplastics typically need to be liquid at <300 C so the glass transition usually is closer to 200 or even less. Definitely not suitable for the engine bay.

Getting it certified for flight is insanely difficult because one of the challenges of AM parts reproducibility.

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

Loads of commercial aircraft and jet engine parts are manufactured using additive manufacturing, or ”3D printing”

Yes… but more often something like laser-sintered metal printing, which is not going to melt when hot.

Yep, and it works even in the SpaceX Raptor engine.

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