Argh! Navion broke

flyingron

flyingron

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FlyingRon
Took off from NC26 this morning to take my plane to CJR for the annual. Got to cruise, leaned it out, and was getting ready to call for flight following when the engine started running rough. Great. Where am I. 7 miles from SVH @ 4500'. Should be able to make that. Engine still producing power. Stayed high until I was close in case it crumps completley.

Enrichen mixture, nada, mag check, nada, reduce power, nada. Check engine analyzer. #2 is cold. Land and taxi to the maintenance shop.

Pull the plugs (they seem OK but one has a dent in the end). Borescope the cylinder and do a compression test. Yep, exhaust valve. Great. At least I'm only 5 miles from home. Wait, isn't that my neighbor's 182 sitting there. Hey, Mike, do you want me to fly your 182 back form SVH. Great. At least that worked out.
 
Those things shake when they lose compression on a cylinder.
When my o-320 did that we replaced a cylinder. maybe you will get away with some valve work at less cost than cylinder replacement.
 
Fortunately, my only two stuck valves both happened on the ground. Both small Continentals (A-65 and O-300) shook badly. Badly enough I'm glad they both happened on the ground.

What engine do you have in the Navion? I used to fly one with an E225. It was a nice comfortable plane. I used to fly big radial engine carburetors from Lawton, OK to a shop in Enid, OK in N4005K. It sure beat driving. :cool:
 
Are you just going to replace the one damaged cylinder or put a whole new set on just in case?
 
flyingron said:
It only has about 900 hours on it since factory new.
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That sucks. Sorry to hear about it, and glad you got down safely.

I've heard of infant mortality on new engines, but yours sounds like a mid-life crisis.
 
Sorry to hear, Ron. Must be the year to replace cylinders. We dumped one last spring due to low compression.

Can you get away with just replacing it?
 
Speedy recovery. Im sure some thought has
been put into checking the others.
 
Well, I went over today and looked at the cylinder. One whole side of the exhaust valve is gone. The question is where did it go? There wasn't any debris in the cylinder. We pulled the exhaust and the baffle in the exhaust pipe looks like it would have caught at least something of it and its clean. Thinking of pulling the intake to see if it is in there. Sure would like to know what happened to it. I don't think it eroded. Just minutes prior the engine leaned normally. The first sign of anything wrong was the vibration (and I was on the ground in 5 minutes). Anyhow the cylinder is off to Triad Aviation to see what they can do with it.
 
flyingron said:
Well, I went over today and looked at the cylinder. One whole side of the exhaust valve is gone. The question is where did it go? There wasn't any debris in the cylinder. We pulled the exhaust and the baffle in the exhaust pipe looks like it would have caught at least something of it and its clean. Thinking of pulling the intake to see if it is in there. Sure would like to know what happened to it. I don't think it eroded. Just minutes prior the engine leaned normally. The first sign of anything wrong was the vibration (and I was on the ground in 5 minutes). Anyhow the cylinder is off to Triad Aviation to see what they can do with it.
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Does it look like the valve fractured and broke, or does it look melted off?
 
flyingron said:
Well, I went over today and looked at the cylinder. One whole side of the exhaust valve is gone. The question is where did it go? There wasn't any debris in the cylinder. We pulled the exhaust and the baffle in the exhaust pipe looks like it would have caught at least something of it and its clean. Thinking of pulling the intake to see if it is in there. Sure would like to know what happened to it. I don't think it eroded. Just minutes prior the engine leaned normally. The first sign of anything wrong was the vibration (and I was on the ground in 5 minutes). Anyhow the cylinder is off to Triad Aviation to see what they can do with it.
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How does that work? If they can't find the debris from the disintegrated valve, do they presume the best or the worst?
 
Ouch on the starting story and double ouch on the chunk going missing. Sorry to hear this for ya Ron. But glad you were able to land it safely.
 
Just out of curiosity, and not that it would make any difference, but how do you generally lean your engine?
 
flyingron said:
Well, I went over today and looked at the cylinder. One whole side of the exhaust valve is gone. The question is where did it go? There wasn't any debris in the cylinder. We pulled the exhaust and the baffle in the exhaust pipe looks like it would have caught at least something of it and its clean. Thinking of pulling the intake to see if it is in there. Sure would like to know what happened to it. I don't think it eroded. Just minutes prior the engine leaned normally. The first sign of anything wrong was the vibration (and I was on the ground in 5 minutes). Anyhow the cylinder is off to Triad Aviation to see what they can do with it.
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Either it is in the intake or on top of another valve or worst possibility it is in small pieces and in other cylinders.

I dropped a valve on a race engine and we found pieces of piston in the radiator tanks as well as the oil pan, intake and in other cylinders. But I bet you were not running the same RPM as I was when it happened....;)
 
To answer the question. It looked like a clean break which is consistent with it just going from normal to nothing on that cylinder.
As my mechanic says "If I was going to fly it, I'd sure want to know where it went." We can't believe it got ground up so small that we'd not find some indication of where it went.
Leaning once we get to cruise is to go from a rather rich mixture (typically 18gph fuel flow) and use the EDM 830 LOP mode. You start dialing back the mixture and the first cylinder peaks and the continue until the last cylinder peaks. On my engine, that typically all happens at the same time. Usually (don't know if this is related) the #2 cylinder (which is the one that failed) is the richest. I run that one about 25 LOP.
If we find the piece, I'd be happy. If we find fragments, then I may want to take a look inside the other cylinders.

Fortunately, I lucked into making my urgent landing at what appears to be a pretty decent shop.
 
flyingron said:
Well, I went over today and looked at the cylinder. One whole side of the exhaust valve is gone. The question is where did it go? There wasn't any debris in the cylinder. We pulled the exhaust and the baffle in the exhaust pipe looks like it would have caught at least something of it and its clean. Thinking of pulling the intake to see if it is in there. Sure would like to know what happened to it. I don't think it eroded. Just minutes prior the engine leaned normally. The first sign of anything wrong was the vibration (and I was on the ground in 5 minutes). Anyhow the cylinder is off to Triad Aviation to see what they can do with it.
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Good luck with those guys. I would give that cylinder a good inspection when you get it back to make sure everything is good. They are known for shotty work.
 
I'd wonder ... something as big as half the head of an exhaust valve won't easily fit through the hole of the smaller intake valve, especially not like they are hammering away...you should at LEAST see some scratches on the intake valve or seat as the thing wormed its way through the intake hole if that is even possible.

You flew it for five minutes with the engine producing some power. There is enough going on in that exhaust system to blow that little metal half-moon around to the point where it wended its way through the muffler and into some farmer's field. Or you will find pieces of it in the oil drain. Or the filter/screen. How did the top of the piston look? Beat up like it tore the piece into dozens of small pieces? Probably not. You can spend dozen$ of hour$ looking for something you will never find.

Or it will freeze your engine over the hills, at night, IFR.

Jim
 
I'm genuinely curious, how could 1/2 a valve get from one cylinder into the next as a couple have hypothesized? Aren't they all sucking in fuel/air and blowing exhaust OUT? Cylinders don't share combustion so how would one migrate to another?
 
I'm with Jim. what does piston/cylinder/head look like? if it's not hammered you need to buy a lotto ticket cause you are a lucky son, it broke and went out the exhaust right away.

I've broke a couple valves. got kinda lucky once as it slapped the piston a couple times and then left, head and cylinder were usable. another one stayed home and destroyed the cylinder, piston, head. basically the whole built motor.

good luck and hopefully it left the motor in a hurry.
 
Ok now there's no excuse. Everyone should buy a $50 USB dental camera and check their valves at each oil change. As soon as burning begins it'll be seen and dealt with....before it fails.
 
There are some dings in the top of the piston but not too bad. Certainly nothing like the cylinder I have off the gopher engine where the entire button of the valve bounced around inside the cylinder for the 90 seconds it took me to make the "impossible" turn back to the runway. That one looks like someone jackhammered the top of the cylinder and the piston, made a hole through the piston and banged up the c-rod. The ring lands on that one were deformed as well.

I don't think it made it's way past the rings into the oil. I'm guessing it's in one of the manifolds or another cylinder.
 
flyingron said:
There are some dings in the top of the piston but not too bad. Certainly nothing like the cylinder I have off the gopher engine where the entire button of the valve bounced around inside the cylinder for the 90 seconds it took me to make the "impossible" turn back to the runway. That one looks like someone jackhammered the top of the cylinder and the piston, made a hole through the piston and banged up the c-rod. The ring lands on that one were deformed as well.

I don't think it made it's way past the rings into the oil. I'm guessing it's in one of the manifolds or another cylinder.
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At the very least, and most likely,,, remove the muffler and find it rattling around in there!
 
Threads like this make me think of all the threads where somebody says they don't want to fly over water, mountains or at night and all kinds of folks pile on with how safe our planes are, how rare engine failures are and how the "engine doesn't know the difference". Then in a thread like this, people pile on with stories of all the numerous engine failures they've had over the years.

These threads usually include pictures of broken stuff, so I believe these threads more. I work hard to avoid night, big water and long distance over mountains.
 
robert lomax said:
At the very least, and most likely,,, remove the muffler and find it rattling around in there!
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There's no "muffler" really, but there's some baffling in the exhaust pipe and it was absolutely clean.
 
Thank you! Great resource.
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I think of it as; gases are flowing in all manner of direction in there - not quite as uniformly or in the discrete manner as one might think. (it is surprising where loose parts can end up!)
 
I don't have the rest of the valve but I do have the little broken off piece. We're going to look at the other cylinders just to make sure it didn't get into the others. We cut the filter and nothing of note there (tiny amount of aluminum but not enough to get worked up over, certainly no steel pieces).
 
Well an overhauled cylinder and a new piston and several amu's later, the plane has been test run fine. Tomorrow I'm going to go fly it (if things hold togehter), I'm taking it back up to my old shop for the annual. Getting the ferry permit was pretty painless. The FSDO emailed me the form and I filled it out and scanned the previous annual and the mechanics sign off that the plane was safe for ferry and emailed it back. Got my ferry permit a few hours later by email.
 
Congrats so far!

Pick out some nice off airport landing spots for the ferry flight just in case.

We kinda like seeing ya around. ;)
 
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