RWM wrote: Blew a cylinder.....off......completely off the case.

Time for me to learn something new!!!!

I would think something was fudged on in order to have a catastrophic explosion of that nature??

Is this what happens when we use connecting rods to long?

Or does the wrist pin separate from the piston if the pistons are used to long?

Does over heating or shock cooling come into play?

I would imagine some engines get field overhauls and the rods, rod caps, and rod studs don't get magnetic particle inspection, or penetrating dye inspection.

If my memory is correct I believe on my MO I got new connecting rod cap studs.

Like I said in the thread about my 540 MO There are many ways to do a field overhaul and when the plane gets sold the new owner is told, yep she was overhauled

My 540 Lycoming flew for 900 hours with a bent pushrod. Rfinkles engine ingested a fist full of aluminum and neither of us had the engine grenade.

These engines are tough and it take some major to make one grenade. IMHO

Where am I wrong???????????

Good day..Rob

When that happens, there is usually a problem with the piston in as it has broken and turned side ways or a piece is on top and it just pushes the cylinder off the studs as that is the weakest point if the top of the cylinder doesn't come off.
There is something hard taking up space in the chamber. the crank, rod, pin are all solid and have the momentum and power to shove the studs out of the case.
Depending on the engine that's a really big event right now.
On some of the radials you could do that on takeoff on a really cold day with lots of manifold pressure and nothing mechanical at all wrong.
IMHO GT

That sounds like my old VW that pulled the case studs.

I think any major engine failure is always the result of a problem that we can see with our eyes and not a microscope. These things are big well designed and run at a speed that should allow them to run almost forever without a failure like that. There are so many "old wives tales" or "urban legends" out there and the most amazing thing is that almost everyone believes some of them.

I have a diesel engine that I will start up in about an hour that has run almost every day for 30 years and has about 10,000 hours and runs about the speed that the 540 runs. It has never been apart. If it fails today I could ask 10 people and I would get 10 reasons like "you used incorrect oil".

It should be easy for someone to determine the cause and it won't be because someone didn't do some trivial thing when it was OH.

I hope we get to hear what failed. There was an IA around here years ago that I wouldn't have trusted to fix a model airplane engine or a lawnmower.

M6RV6 wrote:When that happens, there is usually a problem with the piston in as it has broken and turned side ways or a piece is on top and it just pushes the cylinder off the studs as that is the weakest point if the top of the cylinder doesn't come off.
There is something hard taking up space in the chamber. the crank, rod, pin are all solid and have the momentum and power to shove the studs out of the case.
Depending on the engine that's a really big event right now.
On some of the radials you could do that on takeoff on a really cold day with lots of manifold pressure and nothing mechanical at all wrong.
IMHO GT

GT what is your opinion why a piston would fail?

Desert Rat wrote:It should be easy for someone to determine the cause and it won't be because someone didn't do some trivial thing when it was OH. There was an IA around here years ago that I wouldn't have trusted to fix a model airplane engine or a lawnmower.

Mr. Rat I agree. I am an old tractor and car engine guy from way back.
Do you agree with GT?
I am new to airplane engines. I have met engine shops who will overhaul an engine anyway the owner wants.
Then those engines get passed off as better than they really are.
You really can't be to throw when it comes to what is inside your airplane motor.

Cheers...Rob

Could be a valve stuck and broke the piston, could be the valve broke and then set on top of the piston, could be the valve stuck in the open position awhile back and hit the piston and cause a sharp ridge on the piston, just like the rock nick on your prop? Flaw in manufacture of the piston when made, maybe the prop governor stuck one time and over sped the engine, maybe ran out of gas and had an over speed when relit, during engine out practice on a twin it was put back on line incorrectly and over sped, fixed pitch maybe over sped coming out of a loop before the throttle was pulled back.
maybe wasn't holding your mouth just right when you fired it up this morning, ever had one kick back because your primed it wrong, pulled the power back to quick and it back fired, oh ya shit happens sometimes??Usually when a piston breaks, it is because some thing hit it, or there was some detonation, as in the over speed it usually is the valve that makes a track on top of the piston because the rod stretch enough to let the piston hit
These engines are pretty much bullet proof, even though they are 1930 technology, if they are run inthe manner in which they are supposed to, you take a 235 hp 540 and a 350hp turboed 540, you can do just about anything with the throttle on the 235 hp and not worry about it, and one dumb shove or pull on the other and your out $47,000 bucks!

I agree with the other post, if you look with your eyes and see what you have left, you can probably figure out what happened and where it started.

Have fun looking
GT

Improperly torqued cylinder base nuts can cause a cylinder to leave.

MTV

To be legal, a field over haul has to follow the same guidance as a factory overhaul.

It is manadatory that the same parts be NDI'ed and the same parts be replaced.

The possible difference is in the experience of the mechanic. If he is new to this over haul he might not properly assemble or torque all parts together.

There is also the factor of cleanliness. I have seen shops where I would be afraid to allow them to repair a lawn mower and I have seen shops that are as clean as a hospital room.

Very seldom do the components fail without some outside force causing them to do so.

If your overhaul shop is taking short cuts or trying to hold the price down to please the owner than it may not be a legal overhaul. Some times it is just a repair.

Sorry that your engine blew. I have an O 540 and expect it to last another 1K hrs at minimum.

On a 540, if the conterweights get detuned, it can blow the side right out of the case. Usually takes the studs out along with a large piece of alumnum case. I've seen this on 3 separate 540's. There are shops out there that have NO idea what they are doing with counterweights, and it only takes a counterweight that has been reamed .0005" over/under to cause a failure.
Normally you get a litle bit of warning before it blows(50-100 hrs), alternator mount usually cracks first, or the alternator bearings/housing goes, then you either spot the giant crack spreading around the cylinder base, or it goes bang.

Hey Rob. Was this your new engine?

M6RV6 wrote:Could be a valve stuck and broke the piston, GT

So let me get this straight. Your telling me a 540 Lycoming or 520 Continental is a Zero clearance engine. I never imagined the tolerances were that close.

Sorry the title was misleading. Not my engine. I was from this thread.

RWM wrote: Blew a cylinder.....off......completely off the case.

I am trying to learn why a 540 Lycoming or 520 Continental would grenade. I am starting to see a pattern. Looks like human error. If it is put together CORRECTLY! with GOOD! parts, then operated with in manufacturer parameters it should not grenade.

Good day...Rob

Aircraft engines can be assembled to two different standards and both are legal if done right. You can assemble to "service limits" or to "new limits", most mechanics or shops strive for new limits on all dimensions.

I had an old 125 hp Lyc blow a jug off and tear a big hole in the case. As near as I could tell a piston broke, probably for one of the above mentioned reasons, then the rod jammed and pushed the jug off, then the broken rod flailed around and broke a fist sized hole in the case.

This engine was on an airboat and had been sorely abused for a long time. After the failure we reached into the hole and removed the stub of the con rod, mashed one of the old style oil cans flat and placed it over the hole then carved a wedge out of wood and drove it between the starter and the oil can to seal the hole.

the engine would run on three, not real smooth we drifted most of the way down river to the landing but were able to fire
it up and run into the dock under power.

I remember at one point I was riding in the boat bailing water, (it leaked like a sieve) the others three guys were pulling or pushing against the wind in very shallow water. I looked up at Paul who had a long rope over his shoulder and was pulling the boat along when he stepped right off of the sand bar and disappeared, nothing but his hat floating down stream. In a few seconds he came climbing hand over hand up the rope and we could all ride again.

I had a connecting rod break in the C-145 in my old C170. Dropped down & punched a big hole in the case below the cylinder. Why'd it break? No telling, but I suspect that it had a tiny nick-- perhaps from dropping down & hitting the edge of the case when the cylinder was removed, perhaps just a manufacturing flaw. Who knows how many thousands of revolutions later, that nick turned into a "stress riser" and the connecting rod eventually failed. I also found a cracked piston once when removing a cylinder for a valve/guide job.Eventually it would have cracked all the way around, perhaps grenading something else. "Shit happens" is a cop-out maybe but it does seem to be true.

hotrod150 wrote:I had a connecting rod break in the C-145 in my old C170. Dropped down & punched a big hole in the case below the cylinder. Why'd it break? No telling, but I suspect that it had a tiny nick-- perhaps from dropping down & hitting the edge of the case when the cylinder was removed, perhaps just a manufacturing flaw. Who knows how many thousands of revolutions later, that nick turned into a "stress riser" and the connecting rod eventually failed. I also found a cracked piston once when removing a cylinder for a valve/guide job.Eventually it would have cracked all the way around, perhaps grenading something else. "Shit happens" is a cop-out maybe but it does seem to be true.

I know all about shit happens to the tune of $33,000.00 Mine was human error.

I have heard so many stories about engine issues since I have been on my major overhaul journey. Some of the fixes are cheap and I would not want to fly behind them.

I have been approached by several people who want my used cylinders. They want to use them as is. I wouldn't do that.

I have heard of guys going way past TBO because the compression is ok. Well maybe the engine needs to be checked for cracks?

Just because it seems to run fine might not be the whole story. Mine was running great! I had 25% of guys say run it till it gets bad. The metal in the oil was in the caution zone and my AP said he would not ground me till it was in the sever zone.

75% of the guys said you better pull jugs and take look.

Even the engine shop said you can fly it till the metal in the filter take a turn for the worse.

When I saw the bent pushrod, the one piston with nasty scratches, and the wasted cam and tappet I am sure glad I had it inspected.

I could see the scratches on my piston causing it to break and aluminum wasn't even an issue on the oil analysis. Let an engine sit with out pickling it and your playing Russian Roulette.

To pull the cylinders so you can get a real good look inside is not that expensive either.

I'm sure learning.

Sometimes it what you can't see that gets ya.

OregonMaule wrote:I am trying to learn why a 540 Lycoming or 520 Continental would grenade. I am starting to see a pattern. Looks like human error. If it is put together CORRECTLY! with GOOD! parts, then operated with in manufacturer parameters it should not grenade.

Lexus (somewhat quietly) replaced over 150,000 motors in North America in the late 90's and early 2000's. It was a design flaw apparently blamed on some of the worlds most expensive engine-assembling robots Toyota could buy. Many of these engines " grenaded ".

I'm in the "shit happens" camp. Cop-out notwithstanding...if your motor was built by humans or robots...it can scatter

Most of the time though, these general aviation recips will start talking to you, in one way or another, when they aren't happy.

SixTwoLeemer wrote:Most of the time though, these general aviation recips will start talking to you, in one way or another, when they aren't happy.

My work airplane engines almost never did. Only had one fail in flight, and that was one on a Cessna 401 that went Tango Uniform while enroute. Total non-event. If I could get a big bore Continental past the first 25-30 hours trouble free, I pretty much knew I was going to TBO. Every time.

Now my own airplanes, that sit... And I gotta pay for out of my own pocket... Those engines don't talk to me, they yell, "F**k You" all the time.

Gump

Later today I'm going to be in the shop where the popped cylinder that started this thread is located. I will ask if they have figured out an obvious cause. Last time I asked about it (plane had just come in) they didn't have a definitive answer.

Speculation at the time was yielding possible causes like:
"maybe had a crack in the case"
"could have had a sudden stoppage (prop strike) at some point"
"piston, for some reason, seized up in cylinder"
"could have been a combination of any of these and others"
.....and so on. It was anybody's guess.

I damn sure don't have an opinion in this case due to ignorance on the subject. I'm just relaying what has been said to me. The mechanic doing the work, however, is no spring chick and has probably seen most everything that an engine can do. He's got around 40 years in the business and followed his dad and brother into the field. He's been around it for a while. I assume, if an accurate interpretation of the mess left under the cowl can be given, he will have as good of an explanation as anybody.

By the way, it was on an O-470 on a 182. There was a large number of parts laying beside the plane that had been "removed without turning a wrench."

Engines seem a lot like people sometimes.
Some fade away gradually.
Some pop their clogs with no warning whatsoever.

One engine will smoke, burn oil, barely make compression, and still run virtually forever.
The owner will smoke, fry with lard, live on coffee and liquor, is named Otis, Clem, Ira, or just Pap, and still lives virtually forever.

Another engine, despite religious fervor regarding maintenance practices will scatter like a pinata at 400 hours.
This owner is an organic, vegetarian, marathoner named Biff. 38 year-old Biff is found stone dead, facedown in the begonias in his driveway, stricken with a massive brain bleed while tying his shoes preparatory to going for his morning jog.

Although better (health=maintenance) habits generally produce healthier, longer lived people/engines, there are no absolute failsafe guarantees, just better or more prudent practices.

nealkas wrote:Engines seem a lot like people sometimes.
Some fade away gradually.
Some pop their clogs with no warning whatsoever.

One engine will smoke, burn oil, barely make compression, and still run virtually forever.
The owner will smoke, fry with lard, live on coffee and liquor, is named Otis, Clem, Ira, or just Pap, and still lives virtually forever.

Another engine, despite religious fervor regarding maintenance practices will scatter like a pinata at 400 hours.
This owner is an organic, vegetarian, marathoner named Biff. 38 year-old Biff is found stone dead, facedown in the begonias in his driveway, stricken with a massive brain bleed while tying his shoes preparatory to going for his morning jog.

Although better (health=maintenance) habits generally produce healthier, longer lived
people/engines, there are no absolute failsafe guarantees, just better or more prudent practices.

Well said....probably the best explanation I've heard yet.

MauleOne wrote:To be legal, a field over haul has to follow the same guidance as a factory overhaul.

It is manadatory that the same parts be NDI'ed and the same parts be replaced.

The possible difference is in the experience of the mechanic. If he is new to this over haul he might not properly assemble or torque all parts together.

There is also the factor of cleanliness. I have seen shops where I would be afraid to allow them to repair a lawn mower and I have seen shops that are as clean as a hospital room.

Very seldom do the components fail without some outside force causing them to do so.

If your overhaul shop is taking short cuts or trying to hold the price down to please the owner than it may not be a legal overhaul. Some times it is just a repair.

Sorry that your engine blew. I have an O 540 and expect it to last another 1K hrs at minimum.

After more reflection I realized I was using the wrong terminology. I was thinking repair.

Sometimes we don't want to admit or believe we need to spend major dollars if the engine is running.

I have heard stories of guys repairing cylinders 1 or 2 at a time, Then mags, then the carb. Then say I've got over TBO hours and it runs great. OOOOOOHKK

I know a couple guys who do their own repairs then get their AP friend to sign off. Just a little more duct tape, bubble gum, a hose clamp here, zip tie there.

When that lower end gets to loose something bad might happen?????

Sometimes we don't want to admit or believe we need to spend major dollars if the engine is running good. Or if like mine only had 900 hr on a Lycoming prop strike tear down. 1000 TTSN

Good day

Left engine on a Cessna 310 IO470 Cont. It ran great, everything normal till it through a rod, broke the case in half but at least the prop feathered even though it was canted downward an an ugly angle. There was no warning what-so-ever. The middle of the take-off run and wham. Engine had 280 hr on it. Great engine till that instant.