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Lost a cylinder on take-off

DakotaHawk

Well Known Member
I'd like some help on troubleshooting...

Christmas Eve - I was taking a wanna-be pilot up for a second flight in my RV. She's starting ground school next week. After a normal engine run-up, we taxied onto the Rwy 34 and smoothly applied power. The IO-360 was purring along, we rolled down the runway, and lifted off. Everything was still running smooth.

At about 350' agl, the engine suddenly started running rough. My #2EGT immediately started climbing, all other EGT stayed normal. I didn't notice any change to CHT, but I was paying attention to other things at the time. I used my airspeed to zoom to about 650' agl, pulled power back to about 1700 rpm, and held airspeed (which had bled off in the zoom) at about 80 mph. I made a shallow left pattern turn to downwind, and then realized that I had the pattern to myself and Rwy 11 directly under my wing.

I chopped the power, dropped in full flaps, and slipped down to land on Rwy 11. I landed on the last 1/3 of the runway since I had made my decision to land when I was over the numbers and I had 650' to lose.

Arlington_AWO_27.jpg


After landing, I did a quick runup, and the engine ran just fine. Back to the hangar - still running fine.

Back at the hangar, I pulled the cowl and did a compression test. Compression was good and I didn't hear any intake or exhaust leak-by. The exhaust stack coming from the #2 cylinder was sooty, the other stack was clean. Pulling the plugs from #2 cylinder - dark brown color.

So... What's next?
 
Assuming fuel injection. Using 100LL? Mags or EI? Any recent maintenance? Do you have an engine analyzer with recorded history?

Dan
 
Assuming fuel injection. Using 100LL? Mags or EI? Any recent maintenance? Do you have an engine analyzer with recorded history?

Dan

I've got the Dynon D100 EMS - I'm going to take the laptop to the hangar this afternoon to see if I can download data. (I've never done this before, so I don't know if I have it set up to record data)

The engine is an IO-360, running straight mogas (except for cross country) for the past 500 hours. One mag, one LightSpeed Ign. Plugs are in good condition with correct gaps.

#2 injector check?

What's an injector check?
 
my wag is

a sticking exhaust valve on #2. I would do a wobble test and make sure my push rods on #2were still straight...

Great job getting her down. How did your passenger react?
 
A little rough and high EGT may also indicate you are losing ignition to one plug. First thing I would do is check wires, connections etc. and replace plugs on offending cylinder.
 
Glad you're safe. I think the default on the Dynon is to record data (I don't remember the interval but somewhere between 1 & 5 seconds probably), so you should be ok.

Cheers,
Greg
 
Seen this before

Scott.

In fact, seen it twice on a friends IO-390. After pulling plugs on the problem cylinder, a chunk of carbon was found bridging the gap.

BeeGee
 
A cylinder miss & rising egt should be no cause for alarm or need for a cool head. Pulling power, pushing the nose over and dropping flaps and heading back to the runway really kept you from determining what the problem was. There was more sleuthing to do.
There are a number of items that could be the cause as others have mentioned.

Perhaps its the way you wrote the issue, but I got far more concerned about the reaction than I did the problem while reading. Even a completely out cylinder, while feels terrible, is no cause for 'I have to get down now'. Let it stumble, climb and access.

A nice pattern while troubleshooting would help pinpoint the problem. You could simply have a fouled plug, bad plug, intake leak, ign wire, plugged injector, or a number of other items. Some of these are difficult to troubleshoot on the ground.
 
I had a wire to #3 from the Lightspeed plasma II come off on takeoff and the engine acted the same way... might check and make sure all wires from the L/S are on and firmly snapped down tight to the spark plug. :)

Stuck valve would be my next direction.
 
a sticking exhaust valve on #2. I would do a wobble test and make sure my push rods on #2were still straight...

Great job getting her down. How did your passenger react?

I pulled the rocker cover and did a wobble test - everything moved, springs were springing properly...

A little rough and high EGT may also indicate you are losing ignition to one plug. First thing I would do is check wires, connections etc. and replace plugs on offending cylinder.

Engine was running very rough, and I'm pretty sure it wasn't just one of the two plugs not firing. I did check connections, everything was secure. I pulled both top and bottom plugs and checked gap and cleanliness...

Perhaps its the way you wrote the issue, but I got far more concerned about the reaction than I did the problem while reading. Even a completely out cylinder, while feels terrible, is no cause for 'I have to get down now'. Let it stumble, climb and access.

Ummm... My passenger was up for only her second flight. Do you really think that I should have continued the flight with a newbie in the plane when I have a perfectly good airport right under my wing?
 
Great job

Scott

Great job getting the aircraft on the ground with no problems. Being that low on takeoff with an engine problem, I think you made a wise choice. Get it safely on the the ground then do some troubleshooting.

Glad your ok.
 
Scott

Great job getting the aircraft on the ground with no problems. Being that low on takeoff with an engine problem, I think you made a wise choice. Get it safely on the the ground then do some troubleshooting.

Glad your ok.

Agreed completely, great job and decision to return safely and not take additional risks.

Taking risks and playing with our own lives should be our choice, but playing with our passengers lives should not be our choice.
 
Ummm... My passenger was up for only her second flight. Do you really think that I should have continued the flight with a newbie in the plane when I have a perfectly good airport right under my wing?

I agree - better to be safe than sorry, especially with a passenger out for a second flight. No sense scaring her more than already done.

Greg
 
. . . Ummm... My passenger was up for only her second flight. Do you really think that I should have continued the flight with a newbie in the plane when I have a perfectly good airport right under my wing?


Was it the Stylist? That was a grat video, BTW.
 
A cylinder miss & rising egt should be no cause for alarm or need for a cool head. Pulling power, pushing the nose over and dropping flaps and heading back to the runway really kept you from determining what the problem was. There was more sleuthing to do.
There are a number of items that could be the cause as others have mentioned.

Perhaps its the way you wrote the issue, but I got far more concerned about the reaction than I did the problem while reading. Even a completely out cylinder, while feels terrible, is no cause for 'I have to get down now'. Let it stumble, climb and access.

A nice pattern while troubleshooting would help pinpoint the problem. You could simply have a fouled plug, bad plug, intake leak, ign wire, plugged injector, or a number of other items. Some of these are difficult to troubleshoot on the ground.
No thanks. I also prefer to do my trouble shooting on the ground.
 
What's an injector check?

Follow the stainless line from the fuel spider on the top of the engine to the offending cylinder on top. Loosen the nut (I think it's a 3/16") and carefully pull out the small injector from the flared end. Check to see if some contamination might've partially blocked it...maybe stick some small safety wire in it. Reinstall.

I had the problem you describe and started pulling everything off the engine and the last thing we checked -- the small injector on the top of the cylinder (I have Lightspeed on the top) had a VERY small piece of junk (it looked like a piece of SuperFil about the size of a pencil head) blocking it.... so fuel wasn't getting into the top...which accounted for the high EGT on my cylinder.

The engine has run great since then.
 
Follow the stainless line from the fuel spider on the top of the engine to the offending cylinder on top. Loosen the nut (I think it's a 3/16") and carefully pull out the small injector from the flared end. Check to see if some contamination might've partially blocked it...maybe stick some small safety wire in it. Reinstall.

I had the problem you describe and started pulling everything off the engine and the last thing we checked -- the small injector on the top of the cylinder (I have Lightspeed on the top) had a VERY small piece of junk (it looked like a piece of SuperFil about the size of a pencil head) blocking it.... so fuel wasn't getting into the top...which accounted for the high EGT on my cylinder.

The engine has run great since then.

Thanks! Easy check that I haven't done yet. I'll do that this evening (while I'm trying to figure out how to download the Dynon EMS).
 
DO NOT stick any wire in the injector orifices. Only use air or cleaning fluid.

They're fairly soft and you could change the diameter.

Best,
 
Good job, Scott!

A cylinder miss & rising egt should be no cause for alarm or need for a cool head. Pulling power, pushing the nose over and dropping flaps and heading back to the runway really kept you from determining what the problem was. There was more sleuthing to do.
There are a number of items that could be the cause as others have mentioned.

Perhaps its the way you wrote the issue, but I got far more concerned about the reaction than I did the problem while reading. Even a completely out cylinder, while feels terrible, is no cause for 'I have to get down now'. Let it stumble, climb and access.

A nice pattern while troubleshooting would help pinpoint the problem. You could simply have a fouled plug, bad plug, intake leak, ign wire, plugged injector, or a number of other items. Some of these are difficult to troubleshoot on the ground.

Kahuna, I respectfully disagree. When in doubt, getting yourself, your passenger, and preferably your airplane down safely is priority number one. Troubleshooting the problem is of secondary priority and not necessarily an immediate need if there are better options for completing the flight safely. Given the situation in which Scott found himself, choosing the available option to land, and to worry about troubleshooting later on the ground, was the best way to ensure the safe completion of the flight. Scott made a good call.
 
Climb and assess?

Kahuna,

Sorry but have to disagree, Scott got it right. The only reason to continue to climb would be if landing safely form the height or position he was in was not and option. Climbing would then hopefully give you enough height to get back on the ground safely.

Ask your self a question.... if you lost one cylinder on the ground just before takeoff would you continue with that takeoff to assess what had gone wrong?

I had a similar event with a prop surge at about 50 ft after take off. Not enough height to turn and land and heading straight towards threes on a hill. I pulled power but continued climb and did a very low level circuit and put it back on the ground where we could find out what the problem was safely.

There are circumstances where you would continue to climb, but to do so to assess the loss of a cylinder is not one of them. To do so invites the engine to quit completely on you. If you have enough height and can get it on the ground thats the place to assess a cylinder out.

Again...... well done Scott....... nothing wrong with your decision making or flying skills!!
 
Also check intake gasket and induction sleeve joints. These have a habit of causing grief and then fine again later.

And why is it you get all these deliciously hot looking passengers..... my mojo is jealous :mad:
 
Scott,

You did a FINE job!!! Glad everyone is safe and on the ground. Always been instructed, do your diag on the ground if at all possible. Again, Great Job! :)
 
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I had the same problem.

....And it turned out to be blocked and partially blocked nozzles in the spray bar of the TBI (throttle body injection). The Mogas is what caused that. All the testing on the ground would not replicate the problem, it was only after T/O when the RPM got up that it would play up. The high EGT's to me indicated a lean mixture, so I pulled the TBI off and discovered the blocked and partially blocked nozzles. Stale mogas was gumming them up. I have found if the plane sits for three weeks or more (and weather can cause that), the nozzles in the TBI are partially blocked.

I have overcome the mogas problem by adding a fuel stabilizer to the fuel and now it doesn't congeal in the nozzles. Lawn mower shops and marine outboard motor shops use the stabilizer for the same reason.

Bob
 
I've got the Dynon D100 EMS - I'm going to take the laptop to the hangar this afternoon to see if I can download data. (I've never done this before, so I don't know if I have it set up to record data)

The engine is an IO-360, running straight mogas (except for cross country) for the past 500 hours. One mag, one LightSpeed Ign. Plugs are in good condition with correct gaps.



What's an injector check?

My money is on the valve. Been there, done that, same scenario. Got lots of advice that it couldn't possibly be a valve since my engine was new, but it turned out to be a tight #2 exhaust. Eventually I bought tooling from ACS to do the "wobble test" but before I did, I managed to confuse myself: I had pulled the valve spring on #2 exhaust, and found the valve to slide utterly smoothly in its guide. It felt as if it had enough play, but one of the old-timers at my airport walked up, wiggled it, and declared it to be tight. Turned out it was, barely. Running a reamer through the valve guide cured it. I went at least 30 hours of flight time with #2 intermittently dropping off before I did the deed. Chased every other conceivable issue.

You can check the injector quickly to rule it out. Unscrew the fitting connecting the stainless injector line to the nozzle. Use a 7/16" deep socket to remove the nozzle assembly from the head. There's an insert in the nozzle that will fall out if you turn it upside down, so be careful. Once you have the nozzle out in your hand, drop the insert out, and peer through both parts (nozzle and insert). If there's something clogging it, you'll see the offending particle. Upon reassembly, there is a preferred orientation of the injector in the head. An "A" stamped on one flat of the nozzle should be down, which is the preferred orientation, but torque governs. 60 in-lb for nozzle into head, 25-50 (do not exceed 50!) for tube fitting to nozzle. More info here: http://www.precisionairmotive.com/Publications/25-020_a.pdf

For what it's worth, I had all nozzles off, did flow tests, etc, eventually changed nozzles, lines, flow divider, plugs, wires, etc. before finally sucking it up and doing the wobble test and valve ream.
 
I'd like some help on troubleshooting...
At about 350' agl, the engine suddenly started running rough. My #2EGT immediately started climbing, all other EGT stayed normal...

After landing, I did a quick runup, and the engine ran just fine. Back to the hangar - still running fine.

Back at the hangar, I pulled the cowl and did a compression test. Compression was good and I didn't hear any intake or exhaust leak-by. The exhaust stack coming from the #2 cylinder was sooty, the other stack was clean. Pulling the plugs from #2 cylinder - dark brown color.

So... What's next?

Had exactly the same thing happen to my IO-360 on takeoff once. It was a small dirt particle in the injector nozzle. The particle was small enough that the cylinder ran fine at any power setting that you're able to do on the ground (short of needing to tie the tail down) but as soon as I applied full throttle, that cylinder went so lean that it couldn't fire. But, there was still SOME fuel being injected and most of it just burned in the exhaust stack, which accounted for the high EGT.
 
I was not there, so do not know exactly how mission critical it was to get on the ground ASAP.

The airline folk here might comment, but sometimes rushing to get on the deck can actually increase the dangers quite a lot.

So before you beat up Kahuna, think carefully about this. The engine was still running and capable of climbing, stay in the circuit area, and do a bit of troubleshooting and don't panic.

Troubleshooting on the ground may not reveal the problem, and may just bite you on the next take off at a worse time. Think about that for a few minutes. What you want to do is do a ROP mag check, and a LOP mag check, one with MAP reduced and a few variables, all logged on your EMS, then land and study the data carefully.

You would not believe what I have found in the air that can never be found on the ground. But you do have to play a cautious line here and know what you are looking at in real time.

One of the reasons I preach education all the time. The same argument as running a tank dry.

Overhead that airfield there is never a reason to panic. This is no way a criticism of the OP, but more data could have been collected with more safety that will be apparent on the next take off.

Seems that the valve matter is quite common in some engines so maybe a precautionary ream would be a good idea.
 
I had the issue as Lars, same people told me it can't be the Valve, but it was. It's worth checking.
 
I've got the Dynon D100 EMS - I'm going to take the laptop to the hangar this afternoon to see if I can download data. (I've never done this before, so I don't know if I have it set up to record data)

The engine is an IO-360, running straight mogas (except for cross country) for the past 500 hours. One mag, one LightSpeed Ign. Plugs are in good condition with correct gaps.



What's an injector check?

I do not trust winter blend mogas. A problem with mogas is it's features are changed seasonally. I had to drain a tank of the stuff once when its vapor pressure was off the chart low.

If this was a second take off, you could have had a fleeting vapor lock, especially with a heat soaked top end.

I would take on some 100LL and go out for a flight test.
 
Here's the follow-up...

Last night I was able to follow up on a couple of the suggestions offered here.
  • I tested fuel tanks for water. No water found.
  • I checked all connections on Light Speed coils and plugs. No problems found.
  • I removed and cleaned the injector insert. Found some sooty colored black on the insert, but no blockage. All injectors looked good.
  • Checked intake gaskets and connector rubber for any intake air leaks. All tight.
  • Downloaded EMS data. Data shows a sharp spike of about ^300F on the #2 EGT about eight seconds after RPM went up to 2700rpm (take-off roll). About 2 seconds later, the #2 EGT dropped low (down to about 250F). Over the next 45 seconds, I reduced power to 1950 rpm, and then chopped power to land. When I chopped power, the #2 EGT picked back up and tracked with the other EGTs.

    takeoffflightnumbers_zpsf25eca26.png
 
Many of the colors run together so it is hard to ID some things. There are lines at the bottom that may be the four CHTs. Is the one that drops below the others CHT #2? If so, and this in not the norm for your engine, there may have been a combustion related issue with #2.
 
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That EGT line sure looks like an interruption to the fuel supply for that cyl from what I can see. Looks like a piece of crud got in the way, then let fuel through, then again partially blocked the fuel at the end.

Did you flow any fuel from the line when you had the injector orifice out??
 
I agree with Mike, it sure looks like a partially blocked fuel line or injector. Not that there aren't other explanations. It looks to begin just prior to takeoff, perhaps taxiing onto the runway, where all EGTs went up a bit but #2 is much higher, running lean. At full throttle mixture is so lean (?) that it quits firing, EGT and CHT drop toward ambient (CHT slowly). After retarding throttle #2 starts firing again but is still too lean, high EGT compared to others. Looks like you added throttle to taxi, #2 briefly quits again, but comes back but still too lean after you reduce throttle.
 
I would try the coke bottle test: remove all the injector line clamps (do not bend the lines), remove #2 and at least one other injector from the cylinder heads, put identical glass jars (coke bottles) under each injector, apply full throttle, full rich, turn on the fuel pump. Wait a minute or so, depending on the jar size, turn fuel pump off. Compare fuel levels in the jars. If #2 is obviously less than the others, you have a flow problem.
 
A stuck valve could give the same readings. It happened, I believe, after a reduction of power. My experience with stuck valves has been on the ground, first start, and in the air after a power reduction.
 
Hard to argue with experience Tom.
While you are correct in thinking that a stuck valve would result in the same kind of data read out, I believe a fuel problem is more likely.
Here is why:
DakotaHawk has been running mogas for some 500 hours by his own account and gumming up the valve stems with lead is somewhat unlikely, although possible. A stuck valve is almost exclusively the result of lead build up in the valve guide or on the valve stem.
Soooo, I think a plugged injector line even temporarily, has caused the rough running cylinder. I am also quite certain that this was not ignition related because of the almost ambient temperature reading on the EGT.
Having 2 ignition sources and one go out would elevate EGT's somewhat and having both go out at the same time on only one cylinder is highly unlikely.
My guess is an obstructed injector nozzle or line.
I don't think vapor lock or water contamination affects one cylinder only.
Let us know what you find, for educational purposes.
 
stuck valve

I'm gonna stick with my stuck valve assessment. While I am certain (would bet substantial money on) that the only other possible explanation is a clogged injector, all the evidence Scott has presented looks exactly what I saw as I chased my issue. Every time it happened was after a reduction in power from wide open throttle and max rpm. One giveaway was in the post describing sooty exhaust stack on the offending cylinder, but not on the adjacent one. Fire is continuing, but it's happening in the exhaust stack, blackening it, rather than inside the cylinder where it belongs.

What will help with troubleshooting is if it happens again. If it's the same cylinder, repeatedly, as it was in my case, then it's not the injector nozzle.
 
A stuck valve could give the same readings. It happened, I believe, after a reduction of power.

Every time it happened was after a reduction in power from wide open throttle and max rpm.

Look at the graph-------egt started up about 2 sec before throttle reduced, peak egt about a second before.

Not saying it isnt a valve, but if so, it was not after pulling power.
 
Sherlock Holmes

Impressive detective work going on here, gents. I don't have anything to add, except that this is really educational and entertaining. If anyone is not yet convinced that an engine monitor with logging is worth it's weight in avgas then they have not been paying attention!
 
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