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-   -   Lost a cylinder on take-off (https://vansairforce.net/community/showthread.php?t=94516)

LifeofReiley 12-26-2012 06:41 PM

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! :)

RetiredRacer 12-26-2012 08:18 PM

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

Lars 12-26-2012 08:52 PM

Quote:

Originally Posted by DakotaHawk (Post 728331)
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/Pu...s/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.

hgerhardt 12-26-2012 09:10 PM

Quote:

Originally Posted by DakotaHawk (Post 728315)
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.

edsong 12-26-2012 09:17 PM

Water
 
I'd check for water in your tanks.

RV7AJeremy 12-26-2012 09:50 PM

+1
 
Quote:

Originally Posted by 9GT (Post 728435)
No thanks. I also prefer to do my trouble shooting on the ground.

Agreed, well done sir.....SINGLE ENGINE....

RV10inOz 12-27-2012 03:00 AM

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.

Adam 12-27-2012 05:01 AM

I had the issue as Lars, same people told me it can't be the Valve, but it was. It's worth checking.

Captain_John 12-27-2012 06:10 AM

Quote:

Originally Posted by pierre smith (Post 728474)
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,

Yes, and an excellent cleaning fluid is Hoppes #9 from any gun store!

;) CJ

David-aviator 12-27-2012 07:07 AM

Quote:

Originally Posted by DakotaHawk (Post 728331)
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.


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