No crankshafts available for 18-24 months

In this one they are shoving a variety of things into the pot; it's a veritable witch's brew. On another YT they were pulling randomly from a pile of scrap metal; chairs, fencing, who knows and that was going to be the crankshaft.
(as much as I criticize their methods....I really wanna do this!)

Comments on this vid:
"I wonder how often they check the metal composition of the mix given they are using various scrap ... lol"

"The formula for the ingredients is a closely guarded secret and as you can see.."

"how do they check the quality of the iron? Carbon content? Silisium content? Sulphur content? Is it left to the arbitrary when putting old machine parts, pots and pans and other metal junk in the oven? I wouldn't want a critical part on my car to be made of brittle cast iron with 4% carbon content when a high tensile strength steel is needed."

 
I believe aircraft engine crankshafts are forged from SAE4340, which through-hardened and is about as tough as any steel alloy can be found. The fatigue properties are further enhanced by nitriding, which puts the outer fibers in compression.
 
"No crankshafts available for 18-24 months"

Sounds like this will make pilots get "cranky" ...

About to get "shafted" if your plane is at TBO ...
 
danhagan said:
"No crankshafts available for 18-24 months"

Sounds like this will make pilots get "cranky" ...

About to get "shafted" if your plane is at TBO ...
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9/10 cranks can probably be sent to Aircraft Specialty Services or equivalent and come out with a yellow tag and minor machine work. That's far, far less expensive than a new one.

BUT, I was talking with Rhonda at Barrett Precision Engines yesterday and she said all the crankcase and crankshaft recertification shops are backlogged to heck and back.
 
Lance F said:
I wonder if this is true. You can get cast steel automobile racing crankshafts easily good for 500+HP off the shelf for less than $2K. You can get forged steel ones for less than $4k (700+ HP). These are US built, and I'll bet the tolerances are better than what TCM puts out when they bother to make any. I'll also bet you could get a qualified race shop here to reverse engineer a TCM 520/550 crankshaft and machine one from a billet steel forging for half of what TCM charges in less than a month, and it would be stronger and have closer tolerances than TCMs. I have a TCM TSIO520NB at TBO and frankly don't know what I'm going to do.
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Are automobile crankshafts hollow to allow for constant speed propellers? The manufacturing process is quite different.
 
mondtster said:
Considering some of the problems there have been with aircraft engine cranks, perhaps it is no worse.
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This. ^
The Lycoming O-320 in my Citabria had a crank AD that was addressed in 2003 (way before I bought it). There were pictures in the logs showing the crank that was removed. It looked like a rusty farm implement after many years of exposure to weather. The plane was not a hangar queen by any definition, being used for instruction several times each week.

One would think that aircraft crank shafts would be the one place you would NOT expect an "oops, we got a bad batch of steel" issue.
 
This is going to make a lot of people re-listen to mike bush on overhauling on condition not tbo…. That’s what we are doing w my club 172 w a 360. She’s 100 hours out but compressions high 70s, oil use is negligible, we’re going to add a full fledged engine monitor and we’re borescoping each oil change.
 
aftCG said:
One would think that aircraft crank shafts would be the one place you would NOT expect an "oops, we got a bad batch of steel" issue.
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The ‘90s and ‘00s were particularly bad for ADs against some major engine components. Some of the best engines I’ve had came from that era but overall I look at anything from that period as suspect. I’m curious what was going on back then that caused so much trouble.
 
Huckster79 said:
This is going to make a lot of people re-listen to mike bush on overhauling on condition not tbo…. That’s what we are doing w my club 172 w a 360. She’s 100 hours out but compressions high 70s, oil use is negligible, we’re going to add a full fledged engine monitor and we’re borescoping each oil change.
Click to expand...
Absolutely the right choice.

Over the many years I've been flying I came to be a Lycoming fan. TBOs were longer and they could generally trusted to get there.
Owners of Continental powered planes always seemed to have cylinder issues and of course shorter TBOs
Somewhere on this forum I learned the line "Continental, can't keep a top end together. Lycoming, can't keep a bottom end in them"
Guess which one is cheaper to deal with? I'd rather pull a cylinder any day over screwing with a cam shaft making metal or a rusty crank.

Flash forward to today, I fly part 135 for a living. Our small fleet of C207s fly 20k hours per year. That means the Continental IO-520s reach TBO every year (!).
The 520 is superbly reliable in daily use. Fires right up hot or cold, never misses a beat. The plane I have flown the most in our fleet timed out at the end of my most recent shift. I could predict exactly which blade it would cough to life on during start. It would settle in to 10 quarts and stay there all the way to the 50 hour inspection. I was sort of sad to know we were pulling one of the best engines I've ever flown behind, but part 135 regulations require it.
You could slap that engine on an experimental and be happy as a pig in poo.

When I'm not breaking in new engines I also fly one of our Lycoming IO-540 (dual mag, yuk) powered Lances. After all my hours behind the Continental, the 540 just creeps me out. It runs okay but it's always got just a hint of auto-rough going on. I get used to it after a day or so but when I jump back in a 207 it's like putting on my favorite jeans.
 
mondtster said:
I’m curious what was going on back then that caused so much trouble.
Click to expand...
From all the reports I've seen over the years, the common root cause was a change in the process from new vendors to an "improved" method to even a change in shop foreman. Certain turbine engines were plagued with similar failures of legacy components over an extended time period. If you look over a period of time crankshafts suffer cyclical failures at the mfg level even though they've been producing the same parts for decades. Turbine wheels are another item that have similar issues over a 40 year time frame. I recall one presentation that showed crankshaft AD issuance moved from shop to shop as a new repair process was adopted but some shops decided to "improve" on it instead of follow the instructions.
Huckster79 said:
make a lot of people re-listen to mike bush on overhauling on condition not tbo
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FYI: people have been overhauling engines based on condition for many years prior to Mike B's entry into the aviation world. He just figured out a way to make money telling people about it.
 
Bell206 said:
From all the reports I've seen over the years, the common root cause was a change in the process from new vendors to an "improved" method to even a change in shop foreman.
Click to expand...

That’s what I’ve assumed was the case was. We see the same things with forgings and castings in the other industry I work in for similar reasons. I’m curious to see what sort of ADs come up in the future for components manufactured during the Covid era, I could see similar failures happening.
 
NavAir said:
...and, as a former machinist, scary...
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Yup. Especially the unguarded pulleys and stuff. No eye or hearing protection either.

I have thousands of hours over 12 years on smaller versions of those lathes and crank grinders. Mostly compressor crankshafts, but a few automotive shafts as well. Rebuilding shop. We weren't cutting cranks out of raw castings. Just undersizing to fix worn journals. Did a lot of cutdown and weldup of the drive ends, too, then machining to size and form. Mechanics would keep using worn drive couplings that weren't a press-fit on the shafts, or worn spline drive gears. Reciprocating loads destroy stuff like that.

That was seriously big steel shot they were using. Our machine used much smaller stuff.
 
kyleb said:
9/10 cranks can probably be sent to Aircraft Specialty Services or equivalent and come out with a yellow tag and minor machine work. That's far, far less expensive than a new one.
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There's only so much one can do to reclaim a crank. Undersizing is generally limited to .010" under standard on aircraft stuff, so if it's already at .010" from a previous overhaul, it'll be toast if it's worn. Some scoring can be bad enough to wreck a standard crank. Too deep to grind out.

Aircraft cranks also need re-nitriding after grinding. That's not "minor" work. Not many places can do it.
 
nrpetersen said:
I believe aircraft engine crankshafts are forged from SAE4340, which through-hardened and is about as tough as any steel alloy can be found.
Click to expand...

Yup. That stuff will fight you all the way. It doesn't cut so nicely like the cast iron in the video.
 
mondtster said:
I’m curious to see what sort of ADs come up in the future for components manufactured during the Covid era,
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I think what is going to be equally interesting will be any fallout from all the regulatory exemptions issued by the FAA, EASA, etc. during the same timeframe. Imagine an AD being issued due to due to one of those exemptions.
 
aftCG said:
Absolutely the right choice.

Over the many years I've been flying I came to be a Lycoming fan. TBOs were longer and they could generally trusted to get there.
Owners of Continental powered planes always seemed to have cylinder issues and of course shorter TBOs
Somewhere on this forum I learned the line "Continental, can't keep a top end together. Lycoming, can't keep a bottom end in them"
Guess which one is cheaper to deal with? I'd rather pull a cylinder any day over screwing with a cam shaft making metal or a rusty crank.

Flash forward to today, I fly part 135 for a living. Our small fleet of C207s fly 20k hours per year. That means the Continental IO-520s reach TBO every year (!).
The 520 is superbly reliable in daily use. Fires right up hot or cold, never misses a beat. The plane I have flown the most in our fleet timed out at the end of my most recent shift. I could predict exactly which blade it would cough to life on during start. It would settle in to 10 quarts and stay there all the way to the 50 hour inspection. I was sort of sad to know we were pulling one of the best engines I've ever flown behind, but part 135 regulations require it.
You could slap that engine on an experimental and be happy as a pig in poo.

When I'm not breaking in new engines I also fly one of our Lycoming IO-540 (dual mag, yuk) powered Lances. After all my hours behind the Continental, the 540 just creeps me out. It runs okay but it's always got just a hint of auto-rough going on. I get used to it after a day or so but when I jump back in a 207 it's like putting on my favorite jeans.
Click to expand...

yea I fly behind both- not in same way you do or the hours but my personal plane is has an ol c-85 w the 0-200 Frankenstein STC and then the lycoming in the club plane. I’m sure I’ll need cylinders on the continental one of these days- I don’t think I’ll get 800 more hours out of Em but the club plane cylinders at 2000 hrs and one may need attention..,

My old continental makes good compression but they aren’t pretty w the borescope, little to no cross hatching left and she uses some oil. Ours beutiful n starts great but no way those smooth cylinders gunna make it 800 hrs to just book tbo.
 
Bell206 said:
From all the reports I've seen over the years, the common root cause was a change in the process from new vendors to an "improved" method to even a change in shop foreman. Certain turbine engines were plagued with similar failures of legacy components over an extended time period. If you look over a period of time crankshafts suffer cyclical failures at the mfg level even though they've been producing the same parts for decades. Turbine wheels are another item that have similar issues over a 40 year time frame. I recall one presentation that showed crankshaft AD issuance moved from shop to shop as a new repair process was adopted but some shops decided to "improve" on it instead of follow the instructions.

FYI: people have been overhauling engines based on condition for many years prior to Mike B's entry into the aviation world. He just figured out a way to make money telling people about it.
Click to expand...

absolutly! He’s just a loud voice getting the message out is all. As we all know lots of folks think that tbo figure is the 11th commandment.

i love it though that there’s as many ways to make a bucks as sand on a beach given some creativity and drive….
 
Huckster79 said:
i love it though that there’s as many ways to make a bucks as sand on a beach given some creativity and drive….
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However, in this context I think it more follows PT Barnum's mantra "there's a sucker born every minute" given the majority of info offered is free for the picking if one so chooses. The funny thing is while some hold TBO as the 11th commandment, there's an equal number who hold that loud voice as gospel even though he's never actually worked as a mechanic. I guess its just another example that ignorance is bliss.;)
 
aftCG said:
This. ^
The Lycoming O-320 in my Citabria had a crank AD that was addressed in 2003 (way before I bought it). There were pictures in the logs showing the crank that was removed. It looked like a rusty farm implement after many years of exposure to weather. The plane was not a hangar queen by any definition, being used for instruction several times each week.

One would think that aircraft crank shafts would be the one place you would NOT expect an "oops, we got a bad batch of steel" issue.
Click to expand...

If you read the docket on AD 20-25-12, you'd see that "oops" doesn't cover it. Even the experts can't agree on what is or isn't acceptable. The metallurgical reports from 2 different labs are not in agreement. And, even when the FAA errs on the side of caution, the argument is made that its really all politics anyway.
 
Clip4 said:
Are automobile crankshafts hollow to allow for constant speed propellers? The manufacturing process is quite different.
Click to expand...
Chrysler had one (Hollow crankshaft) in the 40's-50's. Never had a problem with it.
 
Automotive crankshafts are cast out of nodular iron because of its superior self damping properties. Years ago (>50) they were simpler forgings, like aircraft crankshafts are now, because of the better physical properties although self-damping isn't a superior property of forgings. Automotive cranks also use an elastomeric mass/damper (usually called the harmonic balancer) at the opposite end of the flywheel to control torsional vibration.

The reason aircraft cranks frequently use masses on pins at the back of the crank to control torsional vibration is because the engine needs a powerful order-damping system to drive a propeller, the combination of which has a torsional natural frequency operating at a near-constant rpm.
 
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