[rimunroe]

> A generic example, fridges could easily last 40 to 50 years without maintenance. They wouldn't be all that more expensive either. Volvo, and the B-52 bomber program showed this, with Volvo having some models unchanged for 20 years. The B-52 has been in service longer than most people have been alive.

B-52s require regular inspections and maintenance just like any other aircraft. A fridge is less complicated, but it's still a machine. Even my grandfather's clock needed some work done every couple decades, and it didn't contain refrigerant, a compressor, fans, or have to deal with condensation.

[b112]

Yes but how old are the B-52s? And how much maintenance?

All the parts that have been shown to wear rapidly, have been reengineered and updated across the fleet. Compared to newer platforms, it's a rock.

[rimunroe]

I was responding to you saying we could make fridges which could easily last 40-50 years without maintenance (and somehow not cost much more).

> Yes but how old are the B-52s? And how much maintenance?

They get heavy, months-long maintenance where they replace major components (often including major structural ones) every four years. Presumably there is more frequent minor maintenance before then. I don’t imagine their age of 70ish years is really relevant since I assume they’re approaching Ships of Theseus at this point.

[b112]

I was responding to you saying we could make fridges

Well OK, but you starting out by discussing the B-52, so I responded in kind.

They get heavy, months-long maintenance where they replace major components

Unless the documentary I watched was wrong, and of course it could be, that isn't "just replace things because". Instead, it's "if those components need replacement".

Now, I do recall that sometimes they'll discover an early-wear component, and do fleet-wide upgrades to fix that flaw. But that's different than maintenance to replace worn parts, for of course all B-52s fly different missions, have different wear as a result.

My point is, some of those B-52s are being inspected, but not having much done to them, where as others a lot more.

I don't think you can really, fairly compared a long running platform like the B-52 with a newer aircraft. Not in terms of stability of the platform, because the concept here is "fixing engineering defects that exhibit early wear".

Whenever I buy a car, I attempt to never buy the first year of a model revision. I wait until near the end of that run, often 4 or 5 years in, as car manufacturers constantly update assembly and build to deal with parts they've seen as early-wear. This isn't really debatable in a meaningful way, it's simply what's done.

And that's my point. If you look at my original post, I specify that the way to get 'stable', is to keep the exact same platform, and improve early wear points.

The post I responded to said:

Wear-and-tear, particularly on a heavy lifting robot, would probably be their biggest cost and might always outweigh the cost savings.

So you can see why I was specifying how this can be mitigated.

But all of that said, we clearly know this really isn't true. While people will still use shovels, we now have backhoes for a reason. People could use horses, but we have cars for a reason. Mechanical replacements exist for almost everything, and the wear and tear is cost effective and worth it, even with the price of fuel, maintenance, and regular upkeep.

And, even along with the fact that companies engineer for planned obsolescence and forced replacement.

[rimunroe]

> Well OK, but you starting out by discussing the B-52, so I responded in kind.

...because you used B-52s as an example in your argument that fridges could be made to run maintenance free for decades.

> Unless the documentary I watched was wrong, and of course it could be, that isn't "just replace things because". Instead, it's "if those components need replacement".

Yes, that's how maintenance works. Why would you have thought I was saying it was just for fun? The every-four-years maintenance (PDM) involves a deep inspection of the whole aircraft and replacing parts that are fatigued or otherwise showing signs of wear. I would assume they're doing this because they've found that four years is a good rate to find and replace parts that are going to fail well before they're likely to. Airplane parts wear out after use. Frames experience stress from flying and become fatigued.

Similarly, refrigerant can leak when seals fail. I imagine that on the span of decades outgassing might be a problem too. I haven't dealt with compressor failures personally, but they're mechanical components and I assume eventually lubrication gets to be a problem. Rubber gaskets degrade over time. Fungus/algae can grow in the lines used to drain condensation to the evaporation pan and eventually block them, causing the fridge to build up ice and eventually leak water. Fans will fail over time because bearings wear or insulation on windings degrade.

> My point is, some of those B-52s are being inspected, but not having much done to them, where as others a lot more.

That inspection involves nearly complete disassembly. Which documentary did you watch? Aerodynamic surfaces and structural elements get replaced from fatigue and wear. Parts get removed because of corrosion (airplanes get exposed to a lot of moisture). New components get introduced because systems get upgraded. This is normal and expected, but it's all maintenance. From an article[0]:

---

> Foreman said it typically takes a B-52 between 220 and 260 days to go through depot maintenance, depending on parts availability and whether a bomber has any age-related stress fractures or corrosion that need to be repaired. The Air Force is still trying to figure out how much more time the upgrades might add to that schedule, he said.

> Cracking and other structural issues are common on the six-decade-old B-52, Foreman said, and sometimes require components to be replaced. But the Air Force is used to catching and fixing those problems, he said, and the aircraft should be able last well into the 2050s — perhaps to 2060 — without more in-depth structural upgrades.

---

> So you can see why I was specifying how this can be mitigated.

No, I can't, not to the degree you claimed. I don't think your argument about being able to make a maintenance-free-for-decades fridge--pardon the pun--holds water[1], much less without significantly increasing the cost. If you're expecting them to do all the work of discovering issues upfront, why would the cost of doing that not inflate the price significantly? Also, ongoing inspections of the fridge would cost money.

If your argument is that eventually we would be able to make humanoid robots where the maintenance costs are negligible, then sure, maybe. That seems within the realm of possibility.

But again, you said we could make fridges which didn't need maintenance for several decades. I don't think that's within the realm of possibility. You used something (the B-52) which needs regular maintenance as an example of why we should be able to make something else (a fridge) which needs almost none. This is what I was responding to.

[0] https://defensenews.com/air/2024/02/20/tinker-air-force-base...

[b112]

Well, I still feel the age of the platform, its use case, means that the B-52 is a good thing to point to. But, OK, fair enough... the rigors of military maintenance are indeed there, and of use. And as you've demonstrated, more rigorous than I thought.

I'll take another tact here.

https://forcedistancetimes.com/asymmetric-why-china-still-ca...

You may be aware, but it wasn't until 2017? that China could make a ball point pen from domestic parts. The tolerances of the ball, the machinery to make it, the quality of steel... just wasn't there.

Yet we've had that in the West for most of a century? Regardless, it's not about specific timelines, but instead about the fact that most of our modern world could not be crafted by hand. Modern molding, quality of steel and components, machine tolerances, all of this means we're able to make products to tolerances and specifications that were simply impossible before.

The reason I stressed the Volvo, the B-52, is because they are platforms known for fixing stress points, early wear, resolving manufacturing defects, and becoming far more reliable as a result. Unlike modern manufacturers, who mostly derive profit from full replacement of dead products, the profit motive for the Volvo and the B-52 aren't there in the same capacity.

I have nothing against profit, but in this case I do believe it has resulted in far less research into reliability. And the constant churn for 'new new', results in change with little benefit but a constant change to manufacturing methods, and so on.

It's so demonstrably bad, that Quebec (where I live) has passed laws stating that appliances such as fridges, are good not for a year, or two years, but instead a 'reasonable timeframe'. It's purposely vague, for example a single person buying a $1500 fridge, vs someone buying a $800 with a family of 4 might expect more wear and tear, and the warranty not quite as long.

But the reason behind this law, is fridges used to last a least a decade, meanwhile LG fridges often fail in just a few years these days.

Back to the main point, we have the ability to product parts with incredible consistence and to very finite tolerances. Modern failures are no more down to type of material (you cite rubber, and yes that can be an issue), or to unexpected wear.

What I've been trying to convey is, we have part manufacturing down quite well now. Longer term platforms without change, and constant improvement on unexpected wear points, would result in far better outcomes on that front.

This is a far cry from the original post I replied to, which felt robots would have little use from the overwhelming maintenance costs.

[rimunroe]

I was never arguing that we couldn’t make things more reliable, just that a fridge which lasts 40 years without any failures isn’t realistic

[dragonwriter]

> And how much maintenance?

From what I can find, 50+ man-hours per flight hour, which is pretty far from maintenance free.