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

bbc.com

51–60 of 223 posts

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

#51

It'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.

Per 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

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

#52

Is 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.

> 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.

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

#53

The 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.

Plastics under load have a lower Tg.

Tg does not change with load.

HDT does, kind of, but that’s already covered by the load being defined for the various conditions. HDT is always defined at a specific load so it also does not change with load (since load is fixed).

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

#54

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.

> 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.

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

#56

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.

> 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]

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

#57

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.

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°C.

https://assets.publishing.service.gov.uk/media/69297a4e345e3...

Isn't this simply a part that shouldn't have been allowed to be sold based on it being both faulty and also misleading?

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

#58

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.

> 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.

> The Cozy Mk IV light aircraft was destroyed after its plastic air induction elbow, bought at an air show in North America, collapsed.

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

#59
Hah! 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.

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

#60
post #57

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.

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°…

The implication was that the part took shortcuts and made something that only looked good on the surface. But couldn't stand up to deeper scrutiny.
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