Found cracked and blown plugs during annual

mulligan

mulligan

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Mulligan
MX called today to tell me they found 4 cracked plugs and 5 plugs that had blown out during my annual. Said the plane was still producing plenty of power on run-up before they found them.

He asked what my leaning procedures were and stated that it is very difficult to have a detonation on a turbo but didn't see anything wrong as my procedures are basically by the POH. The EGT and CHT have never come near red line and and always run it a little rich because my #2 cylinder probe runs high.

He called champion and they are sending a free box of plugs but was hoping some of you find MX skilled members may have an idea of what the heck is going on.

It has 230 hours on it but it had 80 on it when I got it. Was a Cessna demo and I am pretty sure they only let their demo pilots fly them and I would think they knew what they are doing so I am a little stumped on this once as I take care of my baby!!
 
So the plugs got blown out of the heads but didn't lose all compression and didn't put holes in your cowling?

Something is amiss in the explanation here.

Or does "blown out" mean the plug came apart internally?
 
Joshuajayg said:
So the plugs got blown out of the heads but didn't lose all compression and didn't put holes in your cowling?

Something is amiss in the explanation here.

Or does "blown out" mean the plug came apart internally?
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He just said the ceramic had parts blow out but was still making good connection and fires 7 times per second. I don't have pictures and have not seen them but he seemed confused on how it could have happened.
 
mulligan said:
He just said the ceramic had parts blow out but was still making good connection and fires 7 times per second. I don't have pictures and have not seen them but he seemed confused on how it could have happened.
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Okay, got it. The ceramic came from together but the plug didn't pull the red handle and evacuate the engine.

Hmm...

Did horse spray water into your intake while the engine was running?

I really don't have many ideas other than bad maintenance practices in the past.

Maybe someone knocked your rack of plugs off the table then just reinstalled them? Maybe someone got carried away with the plug cleaner.
 
This will no doubt start a controversy, but sometimes "running a little rich" can put your engine in a pretty bad place, depending on what you're referencing:

tcm_mixture_sweep.jpg


Not saying its the case, but the high CHT's and ICP's found just rich of peak could conceivably lead to things like cracked plugs.
 
I was reading your post when i came across CHAMPION. No need to read further!
Sell your box of free Champion plugs and get a set of Tempest plugs for your engine. I feel you will be very happy with the change.
 
LT4247 said:
I was reading your post when i came across CHAMPION. No need to read further!
Sell your box of free Champion plugs and get a set of Tempest plugs for your engine. I feel you will be very happy with the change.
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x 1,000
 
Hmmmm....I'm thinking you're running on the wrong side of rich. If you don't want to lean....run +120 deg rich of peak....or go +20 lean of peak EGT. But, 50 deg rich of peak is the wrong place to run and is the ideal place to run for detonation....i.e. your damaged plugs.
 
Checkout_my_Six said:
Hmmmm....I'm thinking you're running on the wrong side of rich. If you don't want to lean....run +120 deg rich of peak....or go +20 lean of peak EGT. But, 50 deg rich of peak is the wrong place to run and is the ideal place to run for detonation....i.e. your damaged plugs.
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This is how my standard numbers are. Thins is where the Cessna Demo Pilot told me I needed to be. Maybe you all can tell more from this?

IMG_0984.JPG
 
run 20 deg lean or more (of the last cylinder to peak or just use TIT) and your CHTs will drop below 400....and probably be down below 370 deg F. You'll see better fuel economy, cooler running cylinders.....and only a few knots slower speed.

I'm certain that is the reason for your plug issue....

I run my turbo charged TSIO-520 like I've advised.....and it's much easier on it.

After you get use to running +20 lean.....take a look at the fuel flow and next time just twist back the mixture to that fuel flow and you be all set in a few seconds.
 
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Checkout_my_Six said:
run 20 deg lean or more (of the last cylinder to peak or just use TIT) and your CHTs will drop below 400....and probably be down below 370 deg F. You'll see better fuel economy, cooler running cylinders.....and only a few knots slower speed.

I'm certain that is the reason for your plug issue....

I run my turbo charged TSIO-520 like I've advised.....and it's much easier on it.

After you get use to running +20 lean.....take a look at the fuel flow and next time just twist back the mixture to that fuel flow and you be all set in a few seconds.
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Thanks. What stinks is that my POH says my fuel flow at 28/24 @ 8,000 should be around 18GPH. As you can see it's already 2GPH more and still running at 410CHT. I guess my real numbers are just unfortunately much higher than POH which stinks cause that equals FUEL $$
 
Not so bad eh Mulligan? So far at least lol.
 
champion had a super batch of bad plugs,why do you think they are sending you new ? they want to see the old ones. they are geting good reports now
 
Curious what your CHT's and fuel flow are when you run peak TIT, assuming it peaks in the green arc. Looks to me you are running in a spot that is pretty tough on your engine with very high ICP's.
 
There is never, ever, any detonation inside an internal combustion otto cycle engine.

...I'll get my coat. sorry. I just can't help it!
 
mtuomi said:
There is never, ever, any detonation inside an internal combustion otto cycle engine.

...I'll get my coat. sorry. I just can't help it!
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Never? Not even light, medium, or heavy detonation? Nothing?
 
Cpt_Kirk said:
Never? Not even light, medium, or heavy detonation? Nothing?
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I think he is referring to the fact what we call detonation is called something else by engine techs, and detonation requires exceeding the speed of sound, ie explosions vs flame fronts. There was a thread on it a while back.
 
There has been a MSB from Tornado Alley Turbo about not using certainChampion fine-wire plugs in turbonormalized IO550 engines equipped with their systems. Cracking of the insulators was a common enough problem for them to issue that MSB. No abnormal ignition events required, just a problem with the plugs. (Champion issued competing guidance at the time basically saying that TAT is making things up)
 
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Whew! 20 replies and all on topic! I think this is a POA record.
 
Joshuajayg said:
Whew! 20 replies and all on topic! I think this is a POA record.
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I'm positive Mulligan appreciates it. He was a little apprehensive to post it but I encouraged him to as there's just too many folks on here that are knowledgeable and experienced with this sort of deal. :thumbsup:
 
Joshuajayg said:
Whew! 20 replies and all on topic! I think this is a POA record.
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mscard88 said:
I'm positive Mulligan appreciates it. He was a little apprehensive to post it but I encouraged him to as there's just too many folks on here that are knowledgeable and experienced with this sort of deal. :thumbsup:
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now ....you two have jinxed it. :lol:
 
It would be nice to see a photo of the plugs... I changed out the plugs in my plane last month... 3 Champion fine wire and 5 massive, all worn out.... with Tempest and it runs so much better....
 
Glenn D said:
It would be nice to see a photo of the plugs... I changed out the plugs in my plane last month... 3 Champion fine wire and 5 massive, all worn out.... with Tempest and it runs so much better....
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I'll ask for them when I pickup. If available, I will post here.
 
Joshuajayg said:
Whew! 20 replies and all on topic! I think this is a POA record.
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So maybe we are figuring this thing out? Pilots answer everything but the question. Mechanics stick to the issue at hand until resolved and then drink beer?
 
Joshuajayg said:
Or does "blown out" mean the plug came apart internally?
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No, it "came from together", get yer PoA English straight. :D

But all seriousness aside, I too vote for a picture of the plugs. As an owner who participates in maintenance, I would like to see the damage to the plugs to have a good idea.
 
so....are the plug problems related to the turbo problems?
 
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I find the ceramic nose broken or cracked on the fine wire Champions all of the time on the Mirage and Malibu. Most of the time there isn't a mag drop issue. This has been a problem for well over 15 years with the fine wire plug, maybe longer. Originally they blamed the problems on detonation and then they said that the blasting medium was getting stuck between the center conductor and the ceramic nose causing the breaks. This didn't happen before with the original two electrode champion fine wire plugs. Many of the failed plugs were found with over 50% of the ceramic nose missing. Where did it go?
 
kmead said:
Where did it go?
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Out the exhaust.

I was looking into it a little more today and as some mentioned, it may have been Champion's fault. They had some known plug issues for a while.

410 CHT is a bit high for my taste (although not above manufacturer's limit) and constant running under high power settings with that heat may have exasperated the weak Champion plug issues.
 
Is the 410 in cruise ? You may want to have someone take a close look at your baffling.
 
the 410 CHT will come down if he doesn't run it near max/peak EGT. 50 deg rich of peak is at max CHT....see the charts posted above.
 
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Joshuajayg said:
Out the exhaust.

...
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I'd be a wee bit concerned that those bits of ceramic may have scored the cylinder walls before being ejected...
 
weilke said:
Is the 410 in cruise ? You may want to have someone take a close look at your baffling.
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MAP/RPM/Mixture settings have the most control over your cylinder head temps. I can do almost anything I want with those knobs. He needs to adjust his settings to reduce those temps.

Baffling is important, but I doubt it's even a suspect in what he's seeing in that pic.
 
[QUOTE="Joshuajayg, Out the exhaust.

Surprisingly I haven't seen any damage in the cylinders but I have found damage on the turbochargers turbine blades that appeared to be FOD.
Both engines seem to be doing well with the Tempest fine wire and Champion massive electrode plugs.
 
kmead said:
Surprisingly I haven't seen any damage in the cylinders but I have found damage on the turbochargers turbine blades that appeared to be FOD.
Both engines seem to be doing well with the Tempest fine wire and Champion massive electrode plugs.
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bingo....and he just replaced the turbo too. :eek:
 
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