An A&P-IS's best insurance.

James331 said:
Much at stake, yes, people lives.

Besides:

Tom started this thread himself

The facts are the facts, the prelim and factual NTSB reports have been linked to, and are available for anyone to read.

The NTSB clearly placed the blame on Tom, not POA, not me, not the admin, the NTSB.


or.... maybe he could get the NTSB to erase those reports off their website too.


The facts are the facts, don't fear them, fear those who wish to hide them.
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Nobody fears the facts, but this is people's lives we are garnering our entertainment from here, and that is what this is for some baiting Tom, entertainment or revenge or whatever.

I'm not sure the NTSB should have drawn the conclusion they did from the evidence presented and I would certainly like to see a better explanation as to why that conclusion was reached. If this were an 8th grade science paper it would have gotten a D+.
 
PaulS said:
I'm not sure the NTSB should have drawn the conclusion they did from the evidence presented and I would certainly like to see a better explanation as to why that conclusion was reached. If this were an 8th grade science paper it would have gotten a D+.
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Well said, and pretty much where I am with it. Leaving it alone, no sense staring the pot with NTSB.

But the folks here.... oh well they'll say what they must.
 
Dana said:
Probably way too late, but rechecking the calibration on that torque wrench would be a good idea...
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It is headed for cal Monday morning on the snap on truck. I really want to know because now there are two engines in question. don't panic, neither are installed
 
PaulS said:
So the fatigue marks are concerning, but it is important to realize that this engine was probably spinning 2,700 rpm which means once those bolts stopped holding they and the pin were being whacked 45 times a second. Things can happen very fast and each of those striations could represent 9 or 10 successive hits that occurred in a quarter of a second.
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2700 RPM is plenty for a quick stop.
 
PaulS said:
So the fatigue marks are concerning, but it is important to realize that this engine was probably spinning 2,700 rpm which means once those bolts stopped holding they and the pin were being whacked 45 times a second. Things can happen very fast and each of those striations could represent 9 or 10 successive hits that occurred in a quarter of a second.
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That is basically the NTSB theory. If they were loose and backing out, why isn't the parkerizing finish worn off the bolts? the bolts and the gear holes there are installed in do not show any wear.
 
Tom-D said:
2700 RPM is plenty for a quick stop.
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The problem with the quick stop theory is the striations on the dowel pins which seem indicate a cyclical failure, but like I said, those striations could have occurred in less than a second (multiple rotations of the crank with the gear losing center). Had the engine suddenly stopped I would have expected more damage especially to whatever stopped it.

Your story about the engine stalling several times is very concerning, especially for a recently serviced engine. Some pilots are too quick to explain away issues like that and not seek advice from a mechanic or an expert. That can be deadly in my opinion. That stalling could have been the engine telegraphing its impending failure.
 
Tom-D said:
That is basically the NTSB theory. If they were loose and backing out, why isn't the parkerizing finish worn off the bolts? the bolts and the gear holes there are installed in do not show any wear.
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They were safety wired in, they shouldn't be backing out. I think the NTSB was too quick to count out bolt failures from manufacturing issues or metallurgy issues.
 
PaulS said:
The problem with the quick stop theory is the striations on the dowel pins which seem indicate a cyclical failure, but like I said, those striations could have occurred in less than a second (multiple rotations of the crank with the gear losing center). Had the engine suddenly stopped I would have expected more damage especially to whatever stopped it.

Your story about the engine stalling several times is very concerning, especially for a recently serviced engine. Some pilots are too quick to explain away issues like that and not seek advice from a mechanic or an expert. That can be deadly in my opinion. That stalling could have been the engine telegraphing its impending failure.
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My feelings exactly, but the owner got the typical symptoms of carb ice, I didn't think mush of it at the time either.

PaulS said:
They were safety wired in, they shouldn't be backing out. I think the NTSB was too quick to count out bolt failures from manufacturing issues or metallurgy issues.
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Need pictures?
 

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PaulS said:
Your story about the engine stalling several times is very concerning, especially for a recently serviced engine. Some pilots are too quick to explain away issues like that and not seek advice from a mechanic or an expert. That can be deadly in my opinion. That stalling could have been the engine telegraphing its impending failure.
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E.g. timing being off with the gear wobbling on the crank during rapid RPM changes.
 
PaulS said:
They were safety wired in, they shouldn't be backing out. I think the NTSB was too quick to count out bolt failures from manufacturing issues or metallurgy issues.
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Do you think a safety wire is sufficient to keep a bolt from turning the 1/xth of a turn it takes to lose preload ?
 
Tom-D said:
My feelings exactly, but the owner got the typical symptoms of carb ice, I didn't think mush of it at the time either.


Need pictures?
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Is that the failed gear before install?
 
weilke said:
Do you think a safety wire is sufficient to keep a bolt from turning the 1/xth of a turn it takes to lose preload ?
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safetied as they were, they didn't back off and as pictured was still in place
 
weilke said:
Do you think a safety wire is sufficient to keep a bolt from turning the 1/xth of a turn it takes to lose preload ?
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No, but I think the safety wire would prevent the bolts from backing out and damaging the case.
 
weilke said:
E.g. timing being off with the gear wobbling on the crank during rapid RPM changes.
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Mags are driven by the cam gear. it never came loose.
 
PaulS said:
Is that the correct grade bolt? Not familiar with the SA stamp on it.
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It is a TCM part number manufactured by them and bought thru a authorized dealer.
The owner bought all parts and drop shipped them to me -- 4 new ECI cylinders, 1 new crank, 4 new rods, 8 new lifters, 8 new hydraulic units, new cam, 2 new accessory drive gears 8 new bolts to hold them, two new oil pump gears, new superior main and rod bearings, new intake hose kit, two new slick mags, new carb, and a rebuilt generator, new mount rubbers, assembled with all new hardware. Cases were reworked by Chuck Ney enterprises.
 
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James331 said:
What a miserable way of life, must be like living under isis or the nazis, demanding worship while still invoking fear from their underlings.

I'd think with how many of these creation myths are written, God should normally be loved, looked up to, enjoyed, many things, but any god that you should fear, that sounds more like a devil or the antagonist of the creation story.

Best way to look at it, you don't need to worship anything or anyone, just live a honest life, be nice, leave it a little better than you found it, and any God worth worshipping, or that you'd even want to spend eternity with, would be glad to have you.

Still it's like a bonus round in a video game, live your life expecting to die, bloat, pop, and breakdown for critters to eat, cut to black. Now if by chance you end up being greeted by some long haired bearded hippy looking dude, or the flying spaghetti monester, or whatever, cool, bonus. IMO life's too short to life your life expecting such outlandish things.

But to each their own, but I feel much pity for the poor souls who spend their lives worshipping...and sadly fearing, their god.
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Funny you'd take the time to craft such a lengthy response to that comment....must be bored
 
MtnMarcus said:
Funny you'd take the time to craft such a lengthy response to that comment....must be bored
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Some folks must pick the nit and make issue, over the simplest statements.
 
Tom-D said:
This is what's confusing to me, all 4 bolts broke, yet not a scratch in the finish? simply sheared at the mating surface.
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They did manage to beat their respective holes into an egg shape. The difference in shape between the holes with the bolts that bolted and the bolts that were found in the sprocket at the teardown supports that they came out earlier. The worn out holes argue strongly against a sudden stoppage as the only event that caused the damage.eggholes.JPG

Annotated detail from Fig3 in the materials lab report (red annotations added by myself):
 
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weilke said:
They did manage to beat their respective holes into an egg shape. The difference in shape between the holes with the bolts that bolted and the bolts that were found in the sprocket at the teardown supports that they came out earlier. The worn out holes argue strongly against a sudden stoppage as the only event that caused the damage.View attachment 49067

Annotated detail from Fig3 in the materials lab report:
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Yes, it almost looks as though the bolt at 4 o'clock failed first, then the one at 7, then maybe the pin and the final two bolts. It's late, I'm going to bed.
 
Tom-D said:
This is what's confusing to me, all 4 bolts broke, yet not a scratch in the finish? simply sheared at the mating surface.
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Here are the bolts that remained with the gear close up. I would say they show wear (red annotations are mine, not the NTSBs).

bolts_that_remained.JPG

These are the bolts that fell out. It looks like they backed out, got bent crooked when they hit the case and stopped rotating. The wear pattern is on the 'knee' portion of the bent bolts (red annotations are mine, not the NTSBs).

bolts_that_left.JPG
 
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weilke said:
Here are the bolts that remained with the gear close up. I would say they show wear.

View attachment 49071

These are the bolts that fell out. It looks like they backed out, got bent crooked when they hit the case and stopped rotating. The wear pattern is on the 'knee' portion of the bent bolts.

View attachment 49072
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Well that settles that, those pictures are the first I've seen that showed this. and I was never allowed to see these bolts up close, or hold them. that goes for the gears too.
 
Tom-D said:
Well that settles that, those pictures are the first I've seen that showed this.
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Those are magnified details from Fig 1 in the report named 'Materials Laboratory Factual Report No 16-024' (appended to this post).
 

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weilke said:
Those are magnified details from Fig 1 in the report named 'Materials Laboratory Factual Report No 16-024' (appended to this post).
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now that you've linked me, I can see them.
Thanks for the help in understanding this, You've added a great conversation to this thread.
next I must figure out how to prevent this from ever happening again.
My thoughts
This was a new crank, and new gears, (very tight fit) and may have gotten cocked side ways and took proper torque with out being seated.
my wrench gets checked on Monday. If it is bad--- I'll go pull the 2 engines that I have in service and tear them down again as warranted service. One is my V-EZ engine that's not a problem, the other is the C-85 on my customer's C-120. I'm certain he will co-operate it is winter. he's away.
 
You mentioned that you got the bolts drop-shipped from TCM. So you don't have any other bolts from that batch at hand that you could send off to be tested ?

In what order do you tighten bolts ? If you tighten them crosswise, it wouldn't make sense for two bolts next to each other to be insufficiently tightened while the pair on the other side got the right torque.

One possibility would be a contamination on the side with the dowel that was subsequently ground up causing loss of pre-load (similar to what was alledged in the 'gasket maker' verdict).

The other possibility would be that some sort of burr on the dowel kept the sprocket from mating to the underlying crank flange. Your wrench clicks off and all is well. The burr gets worn off and the bolts lose their pre-load.
 
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Tom, If all the parts were new, meaning they had never been assembled before, is it possible that the bolt holes in the crank weren't machined deep enough and the bolts bottomed out before any real bolt preload occurred? Or maybe you ordered the correct bolts but the ones you received were slightly too long and bottomed out?

Problems such as these would create a situation where you believe you applied the correct amount of torque to the bolt, yet little or no actual torque ended up on them. Just a thought.
 
Mason said:
I don't understand how bolts can back out if safety wired.
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Me either. But if the gear was in a bind on the shaft, (not seated correctly) it can be torqued correctly and loosen in service.
 
weilke said:
You mentioned that you got the bolts drop-shipped from TCM. So you don't have any other bolts from that batch at hand that you could send off to be tested ?

No they came from a supplier.

In what order do you tighten bolts ? If you tighten them crosswise, it wouldn't make sense for two bolts next to each other to be insufficiently tightened while the pair on the other side got the right torque.
These are only 1/4" bolts they require a low torque, my book is out in the shop I won't quote a figure.

One possibility would be a contamination on the side with the dowel that was subsequently ground up causing loss of pre-load (similar to what was alledged in the 'gasket maker' verdict).

The other possibility would be that some sort of burr on the dowel kept the sprocket from mating to the underlying crank flange. Your wrench clicks off and all is well. The burr gets worn off and the bolts lose their pre-load.
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pretty much.
 
mondtster said:
Tom, If all the parts were new, meaning they had never been assembled before, is it possible that the bolt holes in the crank weren't machined deep enough and the bolts bottomed out before any real bolt preload occurred? Or maybe you ordered the correct bolts but the ones you received were slightly too long and bottomed out?

Problems such as these would create a situation where you believe you applied the correct amount of torque to the bolt, yet little or no actual torque ended up on them. Just a thought.
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I'm thinking about the same thing. but they were the correct part numbers and the right size.
The dowl its self could have been binding. I guess I'll never know for sure.
 
K
Tom-D said:
This was a new crank, and new gears, (very tight fit) and may have gotten cocked side ways and took proper torque with out being seated.
.
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This was my first thought too. Hot oil bath for the new gear on a new shaft before installation might be a good checklist item.
 
weilke said:
Here are the bolts that remained with the gear close up. I would say they show wear.

View attachment 49071

These are the bolts that fell out. It looks like they backed out, got bent crooked when they hit the case and stopped rotating. The wear pattern is on the 'knee' portion of the bent bolts.

View attachment 49072
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So I look at these pictures where one bolt is showing essentially 2 full threads and the rest are showing either 3 or more full threads, then I look at the picture of the crank end, picture 27


upload_2016-11-6_9-6-32.png


I see the bolts broke off more or less flush with the face of the crank, that makes me think that they weren't equally tight.
 
Strange that the Feds didn't check toms torque wrench. In any event , I'd be prone to Deal with Charlie at zephyr. We are talking about 1930s technology here. A very simple engine that went wrong.
 
SCCutler said:
I believe it is possible that the bolts could fail in a failure sequence that starts with properly-tightened bolts.

I know I was not present when the mechanic in question installed the gear.

I have seen NTSB reports reaching clearly-flawed conclusions. And, I have personally witnessed premature failure of properly-installed bolts on an engine, in such a manner that examination strongly suggested improper installation.

Looking carefully at my palms, I see no nail holes, and believe I (as do we all) live in a glass house.
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I have a 2" long scar on my hand, had to go get a bunch of stitches. I got it tightening a new OEM track bar bolt to spec 65 ft.lbs with a brand new craftsman torque wrench. The bolt snapped clean. Only possible explanation is that it was a defective bolt.

Had it failed later I could be dead. If you lose a trackbar bolt, you lose steering. Would hate for that to happen at 70mph on the interstate.

I agree from the oblong holes in the pics, it appears that the bolts moved around for some time. I would also agree that the NTSB's conclusion is reasonable, but it's not gospel.

At the end of the day i'm glad that no one was killed and I'll chalk it up to **** happens. I don't think Tom is some sort of rouge mechanic and I know that he understands the basic importance of a torque wrench and tightening bolts in sequence. Maybe he forgot this one time, maybe he misread the torque spec in the manual, or maybe the bolts were bad. Who knows.
 
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I'll tell you what I see, here.

From years of watching and reading Tom's work, he has always seemed to me to be extremely detailed, meticulous.

Through this current process, even in the face of some pretty offensive comments, he has maintained his calm demeanor, seeming only interested in understanding what went wrong.

Me, I'd fly behind (or, in the Vari-Eze case, in front of) one of his engines any time.
 
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