T206H: Excessive Cylinder Replacements

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delta727

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delta727
Hi Everyone,

New to the Maintenance Bay!

I’m looking at leasing a T206H that’s currently on its third owner with about 1200 TT. The first owner put 1000 hours on the engine (TIO-540-AJ1A) over an 8 year period, which included 11 cylinder replacements during that time: the #2 cylinder was replaced 4x in the first 600 hours, then all 6 cylinders at 850 hours, and the #3 cylinder at 875 hours. The airplane was sold at 1000 TT and again at 1100 TT to its current owner.

I’m encouraged by the fact that after the first owner there were no additional cylinder replacements and the compressions are currently 70/73/75/73/74/70. Should I be thinking of the top overhaul at 850 hours as having effectively “wiped the slate clean” or are the numerous past cylinder replacements potentially a safety concern even though the engine is now run very conservatively (65% power, 75 degrees ROP)?

Thanks for any thoughts!
 
What CHT did they target in climb and cruise?

How did they manage power and mixture and cowl flaps in the decent and climb?

That many blown jugs sounds like it might be a user error.
 
Does the plane have a digital engine monitor? If so, I’d go for a demo flight and see what the CHTs look like. It sounds like the previous owner was flying around at high power, peak EGT all the time or something.
 
The TIO-540-AJ1A wasn't the best design and it has poor cooling caused by the top mount intake. There's a long story behind this, but basically the AJ is the most prone Lycoming to cylinder replacements because of its design. Normally Lycomings you almost never have to worry about cylinders on, Continentals replacing them is a fact of life. The AJ is the exception.

However, the top overhaul is going to wipe the slate clean. Keep CHTs at or below 380F, keep EGTs at or below 1550F, run 65% power cruise, and you should be fine.
 
@James331: Unfortunately I don’t know how the first owner flew the airplane. I had assumed the same thing you did, that these problems were caused by poor engine management techniques. Although you would have thought the owner learned a lesson or two along the way!

@Jmcmanna: Yes it has a G1000 with the data logger. I’ll definitely ask to pull the SD card after my demo flight. Thanks for the suggestion.

@Ted DuPuis: Appreciate the context here. I didn’t realize the AJ had this history. Actually makes me feel somewhat better to know that jug changes are a fact of life on this engine as opposed to something being way out of whack with this particular serial number.
 
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Given the AJ history, it’s no where near that bad. I’ll bet money the issue was how it was flown. Turbos are notorious for poor flight ops. Run them right they are awesome.

an over generalization... excessive high EGT means replacing exhaust and turbos, CHT’s over 380-400 means cylinder replacement.
 
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You know, if babying piston turbos is the only consistent way to make the life the OEM advertised, maybe they should placard those watered down parameters as 'the limit'. Marketing wouldn't like the numbers though...:lol:
 
hindsight2020 said:
You know, if babying piston turbos is the only consistent way to make the life the OEM advertised, maybe they should placard those watered down parameters as 'the limit'. Marketing wouldn't like the numbers though...:lol:
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I have a Turbo-normalized plane and managing the heat is not such a big deal. Just some guys don't manage it well. It does take some extra care. Just keep the CHT's below 400 and Turbo inlet temps below 1600 and your good. Turbo-normalized you're just running the engine at sea-level parameters up high and getting amazing TAS out of the plane.

My 182P is routinely running 160+ TAS above 14,000.
 
NordicDave said:
I have a Turbo-normalized plane and managing the heat is not such a big deal. Just some guys don't manage it well. It does take some extra care. Just keep the CHT's below 400 and Turbo inlet temps below 1600 and your good.
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That's a nice setup. turbo normalizing is more fuel efficient, and the failure modes for loss of wastegate more benign than turboboosted. Getting replacement parts for the STC (exhaust et al) is the achiles heel of that setup from what I hear.
 
hindsight2020 said:
That's a nice setup. turbo normalizing is more fuel efficient, and the failure modes for loss of wastegate more benign than turboboosted. Getting replacement parts for the STC (exhaust et al) is the achiles heel of that setup from what I hear.
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I recently replaced the whole exhaust except for muffler and the cost was $6500 parts and $350 labor, including waste gates. It's helps the set-up is a Rajay and not Cessna. The new waste gates are double the gauge of the original.
 
NordicDave said:
I recently replaced the whole exhaust except for muffler and the cost was $6500 parts and $350 labor, including waste gates. It's helps the set-up is a Rajay and not Cessna. The new waste gates are double the gauge of the original.
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Damn. Not cheap. What kind of longevity did ya (or the prior owner) get out of the old exhaust? It helps to put the cost in perspective when looking at the amortization table.
 
NordicDave said:
I have a Turbo-normalized plane and managing the heat is not such a big deal. Just some guys don't manage it well. It does take some extra care. Just keep the CHT's below 400 and Turbo inlet temps below 1600 and your good. Turbo-normalized you're just running the engine at sea-level parameters up high and getting amazing TAS out of the plane.

My 182P is routinely running 160+ TAS above 14,000.
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What turbo system do you have in a 182P? Is that a Rajay?
 
AA5Bman said:
What turbo system do you have in a 182P? Is that a Rajay?
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The plane is a 182P with 3 major STC's; Robertson STOL, Rajay Turbo normalized, and Hartzel 3-blade Scimitar Top Prop.

Amazing mountain bird. I really like the Rajay twin turbo-normalized set-up. The waste gates are manual with a 4th engine control to activate them. When the waste gates are open the engine operates like a bone stock O-470R. After 5-6000 feet I can start to twist vernier waste gate control. I usually fly 2" over square since that simulates advancing the timing as the combustion process slows for a more complete burn. Mike Bush had an excellent webinar on this topic. Really helps CHT's.
 
hindsight2020 said:
Damn. Not cheap. What kind of longevity did ya (or the prior owner) get out of the old exhaust? It helps to put the cost in perspective when looking at the amortization table.
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The construction quality was first rate and all high gauge stainless. I'd have to check the logs again for total time in service but it was long. It lasted 30 years and 2200 hours if memory serves.
 
NordicDave said:
The construction quality was first rate and all high gauge stainless. I'd have to check the logs again for total time in service but it was long. It lasted 30 years and 2200 hours if memory serves.
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Oh that's great longevity. :thumbsup:
 
Some people have no problem with cylinder head temps in the mid 400s.. it sounds like someone just did not know how to properly manage the engine and cooling

There was some Cirrus in a small dry lease club somewhere in Florida (I won't say anything beyond that) and they needed a ton of engine work after something crazy low like 400 hours.. turns out one of the members of their club would routinely climb at Vx right up into the teens

I'm not saying it was user error, but it was user error
 
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