In this day and age with CNC machining, how are airplane parts still ridiculously expensive?

midcap

midcap

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midcap
I am being serious...anything milled out of a block of aluminum is going to be way better than any cast part.

Is the part 23 re write going to address any of this?
 
i don't know about the Part 23 rewrite, but I'm sure the current volume of production & parts replacement wouldn't support retooling and recertifying the manufacturing process on a current type certificate.
 
Unfortunately, most airplanes are still hand-made and labor intensive. GE has been doing some prototyping with 3D printing on scaled-down components but so far, not cost-effective. I used to work at Boeing and made the Obligatory Pilgrimage to Seattle (altho I didn't work for Boeing Airplane) for a tour of one of the factories. I am not kidding when I say even the airliners are still handmade. If you've seen the video of the 777 or 787, you'll see people putting the pieces together.

What parts do you suggest can be made with the CNC technology? Other than the engine case and crankshaft, I can't think of anything on the cherokee or the 787 currently cast that would be suitable for CNC. However many of the large aluminum parts of airliners are cut using CNC.

On the other hand, I'd really like to be able to use 3D printing for the cosmetic parts, such as window trim, panels, etc.
 
Just keeping and inventoring a part for x months or years and having it on the shelf when someone wants it costs way more than the part itself. Cessna builds what some 500 small GA aircraft a year now?

If a Cessna built 100,000 172's they wouldn't cost any more than a car. They weigh less and have fewer parts and are simpler than a car.
 
They know that many airplane owers are rich, and if they are not, they will still give up most everything else in their life to keep flying.
 
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midcap said:
I am being serious...anything milled out of a block of aluminum is going to be way better than any cast part.

Is the part 23 re write going to address any of this?
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so what's up with the grain geometry in a cast part? vs a "block" of aluminum?.....and is this thingy gonna be heat treated? or just soft metal?

and what about additive manufacturing?....that's an easy one too....right? :D
 
I know at least one gentleman who is laser scanning his plane, a part at a time, in order to cnc as many of his own parts as possible.
 
GlennAB1 said:
Can everything that is cast, also be milled or are there limitations to either process?
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There are limitations to each based upon geometry. Also depends on how many axes a mill/lathe has.
 
GlennAB1 said:
Can everything that is cast, also be milled or are there limitations to either process?
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Some parts are cast and milled. What are we 'posed to do about that buckwheat?
 
Airplane parts are ridiculously expensive ... because they can be ;) and because of the certification process... and liability.
 
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murphey said:
What parts do you suggest can be made with the CNC technology? Other than the engine case and crankshaft, I can't think of anything on the cherokee or the 787 currently cast that would be suitable for CNC.
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Many things on aircraft can and are made with CNC technology. Bearings, wing ribs, landing gear components, brackets, wing skins, etc. are made with CNC machines. CNC machines, however, are expensive and still require operators and skilled programmers. They require maintenance, new inserts for tools, etc. CNC isn't just push a button, load the material, and out pops a part.

Things that are still cast are cast because it's cheaper and easier than cutting them out of a large bar (or plate) of material.
 
Shepherd said:
I know at least one gentleman who is laser scanning his plane, a part at a time, in order to cnc as many of his own parts as possible.
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Now that sounds interesting. I would like to know how that project comes about.
 
skier said:
Many things on aircraft can and are made with CNC technology. Bearings, wing ribs, landing gear components, brackets, wing skins, etc. are made with CNC machines. CNC machines, however, are expensive and still require operators and skilled programmers. They require maintenance, new inserts for tools, etc. CNC isn't just push a button, load the material, and out pops a part.

Things that are still cast are cast because it's cheaper and easier than cutting them out of a large bar (or plate) of material.
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Go back and read my post....I asked what parts that are currently cast could be produced with CNC instead. I agree that many of the non-cast parts are currently CNC'd.
 
Don't get cast parts mixed up with forged parts which are then machined.
 
Yesterday I got the bill for 6, 0-300 rod assemblies that I sent in to get re-bushed and re-honed. $700.00. remember these were my parts to start with. and you worry about new parts costs. ?? this is why this industry is dying most aircraft in the fleet are not worth the cost of an engine re-build.
Then there are the dreamers and the suckers --
http://wenatchee.craigslist.org/wan/5988639665.html
he wants 13,500 fora project, and he'll probably get it.
 

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coloradobluesky said:
Just keeping and inventoring a part for x months or years and having it on the shelf when someone wants it costs way more than the part itself. Cessna builds what some 500 small GA aircraft a year now?
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Cessna sold just 143 piston engined 172s in 2015 -- and that was the best selling piston plane on the market. Beyond pathetic.
 
Jay Honeck said:
Cessna sold just 143 piston engined 172s in 2015 -- and that was the best selling piston plane on the market. Beyond pathetic.
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Better than the 80s/90s where Maule was the largest manufacturer of piston engine airplanes...they built 80 a year.

That's 80 or fewer AIRPLANES, not of a particular model, for every manufacturer.
 
Zeldman said:
Now that sounds interesting. I would like to know how that project comes about.
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He makes specialty racing parts, and is also a subcontractor for military weapons parts, and aircraft parts, so he has all the equipment he needs, to scan, cast, CNC and mill just about anything.
I hang out there, whenever I can, just to watch the machines.
 
Shepherd said:
He makes specialty racing parts, and is also a subcontractor for military weapons parts, and aircraft parts, so he has all the equipment he needs, to scan, cast, CNC and mill just about anything.
I hang out there, whenever I can, just to watch the machines.
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I bet it is really cool to watch..!!!
 
Checkout_my_Six said:
so what's up with the grain geometry in a cast part? vs a "block" of aluminum?.....and is this thingy gonna be heat treated? or just soft metal?

and what about additive manufacturing?....that's an easy one too....right? :D
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Considering most of the GA planes still flying were made with 1940's tech, it should be pretty easy to get the parts right for an airplane in 2017.
 
GlennAB1 said:
Airplane parts are ridiculously expensive ... because they can be ;) and because of the certification process... and liability.
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The cert process is what I was talking about. Stuff is so much better these days.

I think liability isn't as a big part of the price as it really is.
 
midcap said:
Considering most of the GA planes still flying were made with 1940's tech, it should be pretty easy to get the parts right for an airplane in 2017.
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And you just hit on the reason we can't CNC new parts. The old parts are hand fitted, so no two fit exactly the same.
 
One thing to remember in aeronautical manufacturing is that anytime a change is made (such as casting vs milling) there is a very extensive and often expensive testing process that must take place.
 
I work for an airline. We frequently produce parts for use on our aircraft. The process is extensive but when you already have everything you need the expense is minimal.
 
Here's a quick rundown on how that works:
We either use manufacturers engineering drawings or "sample". Manufacturers drawings are preferred, using "sample" requires quite a bit more NDT. We cut a workorder so all documentation is retained. All steps get two signatures, MX and QC, except for QC specific steps. Verification includes: material, fabrication, heat treat, corrosion resistance finish, ie., alodine or cad plate, primer, paint. QC specific would be: surface roughness and any required NDT, usually fluorescent penetrant or eddy current are required. We have a standard for surface roughness (visual-tactile). Then part gets a special P/N
 
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GlennAB1 said:
Here's a quick rundown on how that works:
We either use manufacturers engineering drawings or "sample". Manufacturers drawings are preferred, using "sample" requires quite a bit more NDT. We cut a workorder so all documentation is retained. All steps get two signatures, MX and QC, except for QC specific steps. Verification includes: material, fabrication, heat treat, corrosion resistance finish, ie., alodine or cad plate, primer, paint. QC specific would be: surface roughness and any required NDT, usually fluorescent penetrant or eddy current are required. We have a standard for surface roughness (visual-tactile). Then part gets a special P/N
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I don't see why the same can't be done with GA stuff.
 
midcap said:
I don't see why the same can't be done with GA stuff.
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That process is still very expensive, and it depends on the quantity being produced. Each process generally has a minimum lot charge for setup, so gets cheaper with more parts. However, nobody wants to spend the money and then stock the parts without at least doubling their money.
 
Croomrider said:
That process is still very expensive, and it depends on the quantity being produced. Each process generally has a minimum lot charge for setup, so gets cheaper with more parts. However, nobody wants to spend the money and then stock the parts without at least doubling their money.
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How much lead time you think a CNC shop would need before hand? The A&P would be bale to cut out a parts co.
 
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