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This is called the Jesus nut. It holds the main rotor onto the helicopter. It doesn’t have any redundancy, so if it fails, you’re going to be meeting Jesus in moments.
Thankfully this one is built of many redundant layers instead of just one layer of metal.
TIL there’s many Jesus’s nuts are all over the sky.
One time, this was back in my skydiving days so a very long time ago, the drop zone’s CASA 212 was down due to a bad hydraulic pump. The pump finally arrived and the DZO asked me to help him install it. He was a certified A&P, I just had a lot of experience wrenching on cars but it allowed me to get a lot of free jumps due to helping him out on things like this.
He handed me the pump, which was a LOT lighter than I expected and told me with a smile: “Don’t drop it.”
In inquired as to how much it cost and he replied: “$10,000.”
I was holding a pump in my hands that weighed barely 10 pounds that cost more than my car (this was circa 1998 or so).
A couple years later the igniter box on the port engine died and I helped him replace it… That was a cool $15000. The engines were about $250,000 a piece back in those days.
Not needing food or shelter anymore because you’re dead is also great for your budget.
Wont even take off
Going out with a bang is great for everybody’s budget!
Probably until you get to the megaton range. At that point I suspect you’re probably bringing a lot of people with you.
To be fair, if you don’t have the files. This is an easy way to make a prototype and fit it, and then if it fits you can order it in metal. This is a cheaper proces in iternating in metal from the start
If the choice is between being out $1,590 or plummeting to my death in order to save a few hundred bucks, then I’ll just pay the $1,590.
They call it the Jesus Nut for a reason.
Because it makes Jesus Nut?
Because if it fails, only Jesus can save you
No. No.
For this part? No. You want the real deal. The proper metal. The proper alloy, annealed correctly.
Yeah, but to get there, you need a prototype. There’s nothing wrong with testing the fit using 3D printing before you order a copy in real materials, just don’t put it under any load.
You could print it with normal plastic filaments, but those can deform and screw with the measurements if you’ve got a really tight fit, so metal printing is a good use there.
Aerospace manufacturing has a paper trail longer than you can imagine. The company selling this part can tell you (well, the FAA) the exact ingot out of the foundry and every single process and every person who has touched it since then.
No machine shop will take this job; the moment this guy is unable to produce a serial number and paperwork from an approved manufacturer (likely during preflight if not installation) the FAA will track down the owner of said shop. At best that owner will lose their business and pay a massive fine, at worst spend a good long time in prison.
The FAA doesn’t fuck around and for that I am thankful.
How is the machine shop supposed to know it’s an aerospace part? The customer could just give them a reverse-engineered CAD file.
(Academic question, because making this part actually work will cost >$1500 without economies of scale)
Depends on how much effort went into reverse engineering the part, but most likely when tolerancing enters the conversation. Most machine shops aren’t able to hit those tolerances and would laugh you out of the shop.
A shop that can hit those tolerances will kick you out of the shop; there’s a good chance they already work in aerospace. They have a deeply vested interest in avoiding the accompanying FAA inquiry should it be installed or, Satan forbid, actually flown.
A non-aerospace shop capable of meeting those tolerances would start laughing at the desired price point. Purchasing a suitable blank alone would cost over $1500, much less cover the actual machining.
And now you’ve just given Boeing executives some great ideas how to further reduce costs! I don’t thank you!!
I have news for you:
3D printing is very common in the aviation industry by now.
They don’t exactly use TPU and Bambulab printers, though… ;-)Oh yes they do.
Aircraft crashed in Gloucestershire after 3D-printed part collapsed - BBC News https://share.google/v8NcjqE0tAK34AiI7
TPU? You’ll get PLA and like it
“Hey, John! How much are we paying those 3D printers again? I found one here that looks like it would do just the same job for much less!” – quote that will show up in a leak in 2032 after a handful of planes crashes.
ChatGPT said it would work.
AI said it would be fine. Send it.
See, what no one in here realizes is that the plan was to use this as a master to cast an aluminum one. Aluminium is a metal, and metal is strong. I’m sure everything will be fine. Bonus–aluminum doesn’t rust, so it should last forever. OOP wonders why they weren’t made of aluminum in the first place, and figures it’s “planned obsolescence.”
He’s just waiting for his casting kit to be delivered. He expects to be flying again later that day.
This is such a perfect example of why right-to-repair matters: sometimes a “$1,590 part” is really just access. Also, that print looks solid — I’d still check material/heat/vibration limits on a rotor part, but the ingenuity is 💯
