Turbo Ops -- UGH!

[flyersfan31]

OK, so I bought a Turbo 182, knowing that with turbo ownership one acccepted additional costs and complexity.

Accept that disclaimer. Please don't lecture on "you bought a turbo, you knew the cost, you deserve to die." Or some such.

I cooked my turbo last week. Apparently, a bearing failed inside the turbo (rare, I'm told), turbo spun until stuck in the housing, shedding (thank goodness) just a little bit of alumninum caught by the filter. (full oil change, filter change, and 8 hr run in will confirm no metal in engine. I hope. )

MY GRIPE - i've operated at, what I thought were, more conservative #s than Lycoming's recommendations. Initial - max 31.5"/2400/full rich, retard to 25"/2400/16gph at 1000AGL to cruise altitude, 26"/2200 cruise (apprx 75%, 145 ktas/14gph). Everything out of the book.

In fact, book performance specs 50degF of peak TIT. Silly me, I've always operated 100F rich of TIT Peak, usually 1585, thinking I was being conservative. My A&Ps were aghast (I've never seen anyone aghast before -- they were!) They thought I was nuts - they tell a Navaho op on the field to operate at no more than 1475. They thought I was absolutel nuts, nuts, nuts. Moreover, I was told by Cessna Pilots Assoc gurus that taxi time should be enough for a turbo cooldown. My head A&P thought that was nuts, that I should cool with engine running for 3 mins once in my tie down. I thought that would only mean no cooling air, just hot oil around the turbo for a few more minutes.....

I've been reading from Deakin's Pelican's Perch, and now I think I was sold a bill of goods. Any comments from my experienced colleagues???

 

[bbchien]

Okay. So tell us turbo operators how many hours were on this turbo.....and FYI 75% is in no way conservative.

 

[sba55]

Since there's a chance that some larger parts of the turbo came off, make sure that your mechanic inspects not just the oil filter, but also the oil pickup screen. That's important since some pieces might not even have made it to the oil filter.

I've made a few experiences myself:

a) Don't believe most A&Ps when it comes to anything re. your engine. There are exceptions, but they're not easy to find. There's lots of A&Ps out there who've never seen a borescope and who believe that bad compressions = replace cylinder.

b) 75% isn't a problem by itself. Leaning correctly, however, is. At 75%, you shouldn't be any less than 150 dfROP. Also, I wouldn't pull back the RPM to less than 200 below max if you're at 75% ROP. Doing so increases ICPs and significantly contributes to cylinder wear. If you're LOP, it's a different story and you can use the full RPM range at any power setting.

- Deakin's columns are usually spot on.

-Felix

 

[flyersfan31]

Sorry, Doc, I meant to include hrs in my post.

Oil, filter changed, screen cleaned, no A&P signoff until 8hr runoff with no metal in filters.

Bought with 500hrs on the tach. Can't vouch for engine treatment prior to that (although, I have my suspicions, given the fuel tank leakage I know was due to flap extension at/above book recs, and that the OP bought a Columbia 4000). Turbine failure at 620hrs.

Heck, if operating below BOOK numbers isn't conservative, then what is?????

I know, and the research I've done AFTER this incident have shown me that GA piston engine mgmt techniques vary greatly in acceptability and effectiveness.

 

[sba55]

The book numbers for most GA engines are way off, so operating below them doesn't mean anything.

Lyc's CHT red line is 500d. If I operate a "conservative" 80 degrees below that, I'm still going to be in trouble in a rather short amount of time. Their lean recommendation is 50 dfROP. Since that's where the highest CHTs and ICPs are, operating just 20d richer won't safe my engine at 75% power. Book numbers aren't even close to conservative for GA engines. We have to be WAYS below them.

It's sort of strange because almost everything else about an airplane is quite conservative. Vle for me is 145, but I doubt I'd do any damage at 180.

-Felix

 

[Henning]

Sorry, Doc, I meant to include hrs in my post.

Oil, filter changed, screen cleaned, no A&P signoff until 8hr runoff with no metal in filters.

Bought with 500hrs on the tach. Can't vouch for engine treatment prior to that (although, I have my suspicions, given the fuel tank leakage I know was due to flap extension at/above book recs, and that the OP bought a Columbia 4000). Turbine failure at 620hrs.

Heck, if operating below BOOK numbers isn't conservative, then what is?????

I know, and the research I've done AFTER this incident have shown me that GA piston engine mgmt techniques vary greatly in acceptability and effectiveness.

Running 100° ROP is tougher on the turbo than 50° ROP, think about what you are doing, you are cooling using raw fuel which puts unburned hydrocarbons (soot) through the turbo. This, due to exhaust pressure, gets past the seal and cokes up the bearing, which is really a bushing (no rollers). When you get the new turbo, start running it LOP, your wallet will thank you all around.

 

[sba55]

Running 100° ROP is tougher on the turbo than 50° ROP, think about what you are doing, you are cooling using raw fuel which puts unburned hydrocarbons (soot) through the turbo. This, due to exhaust pressure, gets past the seal and cokes up the bearing, which is really a bushing (no rollers). When you get the new turbo, start running it LOP, your wallet will thank you all around.

Maybe 50d is better for his turbo, but it'll kill his engine. I know lots of people who run rich enough not to damage their engine (and 100 dfROP is _not_ rich enough above 70% power), and one of them still has the original turbo in his 20+ year old arrow. But, LOP is the way to go for turbo ops, no argument there.

 

[Henning]

Maybe 50d is better for his turbo, but it'll kill his engine. I know lots of people who run rich enough not to damage their engine (and 100 dfROP is _not_ rich enough above 70% power), and one of them still has the original turbo in his 20+ year old arrow. But, LOP is the way to go for turbo ops, no argument there.

Right, there really is no appropriate ROP setting to maximize turbo life, however, turbos are cheaper than engines in applications like the TSIO-360 and others that are subject to bootstrapping. The T-182 though is not such an application.

 

[flyersfan31]

Running 100° ROP is tougher on the turbo than 50° ROP, think about what you are doing, you are cooling using raw fuel which puts unburned hydrocarbons (soot) through the turbo. This, due to exhaust pressure, gets past the seal and cokes up the bearing, which is really a bushing (no rollers). When you get the new turbo, start running it LOP, your wallet will thank you all around.

Ah, very interesting. Obviously I never thought of that angle.

I experimented with LOP ops, briefly. I wasn't thrilled with performance. IIRC, in exchange for a pretty marked drop in EGT/CHT/TIT I lost 15kts (145ktas vs 129ktas, 14.1gph vs around 12.1gph). The temps looked great, but the speed was almost Sundowner-like. I may rethink that given the cost of a turbo.

 

[flyersfan31]

Oh, and btw - my A&P's think running LOP is insane. Well, maybe not insane, but close to it. They are very adamantly against it. You can see why I'm so perplexed. I'm no thermodynamicist, but the evidence, to me, looks pretty darn strong to support LOP ops.

 

[charlie]

Your engine is essentially a derated 260 so running 75% IS conservative. If you run LOP you get the speed back by increasing the MP. Charlie Melot Zephyr Aircraft Engines

 

[bbchien]

That's young for a turbo to fail, if it were overhauled. I think the prior operator ran it hard.

65% was my solution for TWO TSIO360EB1Bs.

 

[wsuffa]

That's young for a turbo to fail, if it were overhauled. I think the prior operator ran it hard.

65% was my solution for TWO TSIO360EB1Bs.

I'm with Bruce.

65% power on my turbo engine, except for takeoff and initial climb. I have to watch CHT on the engine in climb - it's a bigger limitation.

At 75%+, Lyc. specifies NO leaning. I do run as high as 1600 degrees, redline at 1725. I had the turbo done at 1000 hours - at the same time we discovered a small crack in the wastegate pipe - there was some bearing leakage.

To Henning's point - also make sure that there is no obstruction on the exhaust pipe, including the sections around the wastegate.

My mantra on the turbo is to be conservative.

It's also why I'm strongly considering selling the airplane as opposed to taking on a partner.

 

[TMetzinger]

Keep in mind the discussion was about the turbo failure, not about what damage he may be doing to the cylinders.

Cooler is better for both the turbo and the engine. Cooler LOP is better for both IF you can run your engine LOP smoothly and stay out of the "red box". Some turbocharged engines (Mooney Bravos come to mind immediately) are very hard to run smoothly LOP.

If you can't run smoothly LOP, you can either reduce power (to lower temperatures), or run ROP outside the red box (also lower TITs and CHTs) but you are throwing gas away when you do that, and as Henning says, unburned hydrocarbons are not friendly to parts moving at high speeds.

Walter Atkinson's Advanced Engine Management courses come highly recommended - you will learn a ton about operating your engine, all backed by experimental data rather than OWTs.

Do you have an engine monitor? If not, that should be your first item along with replacing the turbo - they really are required equipment to operate a turbo engine optimally.

Finally, I'm with Bruce - I don't think you "broke" it, there's a great deal of operation before you.

 

[Henning]

Oh, and btw - my A&P's think running LOP is insane. Well, maybe not insane, but close to it. They are very adamantly against it. You can see why I'm so perplexed. I'm no thermodynamicist, but the evidence, to me, looks pretty darn strong to support LOP ops.

Most mechanics aren't all that bright at understanding the physics of combustion within an engine. BTW, measure your power by fuel flow, not MP/RPM. You'll see that you can get even greater speeds for the same fuel running LOP and still keep your temps down and valves/turbo deposit free.

 

[Henning]

I'm with Bruce.

65% power on my turbo engine, except for takeoff and initial climb. I have to watch CHT on the engine in climb - it's a bigger limitation.

At 75%+, Lyc. specifies NO leaning. I do run as high as 1600 degrees, redline at 1725. I had the turbo done at 1000 hours - at the same time we discovered a small crack in the wastegate pipe - there was some bearing leakage.

To Henning's point - also make sure that there is no obstruction on the exhaust pipe, including the sections around the wastegate.

My mantra on the turbo is to be conservative.

It's also why I'm strongly considering selling the airplane as opposed to taking on a partner.

When we talk conservative, we have to also consider what engine we are running. You may want to start thinking in HP/CI rather than % rated power. Bruce's engine is what 220hp produced from 360ci. The T-182 is what, 235hp from 540ci. When run at 75% power, that's .326 of a hp/cubic inch. When Bruce operates his TSIO-360 at 65% power, he is producing .397 hp/ci. So Bruce is running his engine harder at 65% than Flyersfan is running his at 75% power, and IME, when you get below 1/3hp/ci, especially ROP, you are coking up the entire engine, and loading your oil up with a bunch of nasty stuff. If you want to run that low of a power level, you have to get there by restricting fuel flow, not airflow.

 

[flyersfan31]

That's young for a turbo to fail, if it were overhauled. I think the prior operator ran it hard.quote]

Yup, I thought so too. Mind you, it was factory-new, not an O/H unit, since the plane is a 2005 model. Original owner put 500hrs on it in 1.5yrs.

OK, time to sign up for the engine mgmt course. I have a LOT to learn.

Any other recommended sources of info?

 

[kmead]

With the Malibu/Mirage fleet I've seen many turbo failures, some dirty (complete loss of oil) and cleaner (just trashed). Aluminum in the filter is common after this type of failure. What is odd, is that they seem to happen in groups. While I was in CA I had the chance to set through the investigation of a dirty failure turbo. They seem to put a lot of focus on the turbine housing deposits starting the failure. I find that turbos that have been run ROP show a lot more combustion product build up on the turbine housing. Textron addressed this problem on the TIO540 Mirage engine with Textron SB 531 calling for 250hr/annual inspections for signs of turbine rub or damage. We reject many turbos through this inspection. My old Malibu TCM engine ran almost 2700 hrs being run LOP, no GAMI nozzles, single TIT and CHT indicators. My belief on " LOP, " if its smooth and cool your engine is fine.

Kevin

 

[AirBaker]

Any other recommended sources of info?

Sign up for the Advanced Pilot course online. ITs like $600 for the on-line course or $1200 in person. You're flyin a 'big' engine now...

 

[redcloud]

Can't tubo 182's be operated LOP like APS recommends; works like a dream in my 400.

 

[gprellwitz]

How much of the Advanced Pilot stuff can a renter do? I thought it involved looking at engine monitor downloads, etc. Flying the T-210 and T-182 now, I want to be kind to the engines. OTOH, I still need to respect the operations rules that the owners put down on their planes! Just because Advanced Pilot has convinced me that LOP is the right way to go, if the owner's been convinced that it's all wrong and says run ROP, I've got to run ROP as long as it's safe.

 

[Trapper John]

When we talk conservative, we have to also consider what engine we are running. You may want to start thinking in HP/CI rather than % rated power. Bruce's engine is what 220hp produced from 360ci. The T-182 is what, 235hp from 540ci. When run at 75% power, that's .326 of a hp/cubic inch. When Bruce operates his TSIO-360 at 65% power, he is producing .397 hp/ci. So Bruce is running his engine harder at 65% than Flyersfan is running his at 75% power, and IME, when you get below 1/3hp/ci, especially ROP, you are coking up the entire engine, and loading your oil up with a bunch of nasty stuff. If you want to run that low of a power level, you have to get there by restricting fuel flow, not airflow.

That's an interesting perspective. At what point ROP do you think the valves would start to get significant deposits?


Trapper John

 

[wsuffa]

When we talk conservative, we have to also consider what engine we are running. You may want to start thinking in HP/CI rather than % rated power. Bruce's engine is what 220hp produced from 360ci. The T-182 is what, 235hp from 540ci. When run at 75% power, that's .326 of a hp/cubic inch. When Bruce operates his TSIO-360 at 65% power, he is producing .397 hp/ci. So Bruce is running his engine harder at 65% than Flyersfan is running his at 75% power, and IME, when you get below 1/3hp/ci, especially ROP, you are coking up the entire engine, and loading your oil up with a bunch of nasty stuff. If you want to run that low of a power level, you have to get there by restricting fuel flow, not airflow.

1) I have a TO360 engine, so I fall into the same category as Bruce. Hence my perspective.

2) I think the more important equation is whether the cylinder temperatures are high enough that the scavenging agents in the fuel work without being too high.... and whether the deposits will condense on the cooler exhaust & turbo parts.

I'd love to run LOP, but my engine just won't go there. I tend to run a lower power (60% or so) and lean more heavily, while keeping an eye on CHT.

 

[AirBaker]

I'd love to run LOP, but my engine just won't go there.

Got GAMIs?

 

[AirBaker]

How much of the Advanced Pilot stuff can a renter do? I thought it involved looking at engine monitor downloads, etc. Flying the T-210 and T-182 now, I want to be kind to the engines. OTOH, I still need to respect the operations rules that the owners put down on their planes! Just because Advanced Pilot has convinced me that LOP is the right way to go, if the owner's been convinced that it's all wrong and says run ROP, I've got to run ROP as long as it's safe.

Are you paying WET rates? If so, you really have no reason besides courtesy, to operate LOP.

LOP is better on your engine, wallet, but not speed.

 

[Henning]

How much of the Advanced Pilot stuff can a renter do? I thought it involved looking at engine monitor downloads, etc. Flying the T-210 and T-182 now, I want to be kind to the engines. OTOH, I still need to respect the operations rules that the owners put down on their planes! Just because Advanced Pilot has convinced me that LOP is the right way to go, if the owner's been convinced that it's all wrong and says run ROP, I've got to run ROP as long as it's safe.

Yep, If the owner/boss tells me to operate a certain way, that's the way I operate it. It doesn't cost me a dime to burn up their engine.

 

[gprellwitz]

Yep, If the owner/boss tells me to operate a certain way, that's the way I operate it. It doesn't cost me a dime to burn up their engine.

Yes, I'm paying wet rates, but it does wind up costing, because they'll roll the fuel consumption into the rates that they set, and if the owner has to overhaul it soon after it goes on line, guess what isn't going to be on line much longer! Plus, if/when we get our own plane, having good habits already inculcated is a Good Thing. Courtesy ain't a bad motive, either!

But, as you say, the owner or their agent (the FBO) gets to dictate the policy.

 

[Henning]

That's an interesting perspective. At what point ROP do you think the valves would start to get significant deposits?


Trapper John

It depends on actual temps. The cooler the CHT and EGT, the sooner it happens. Operating engines is a balancing act of many factors.

 

[Henning]

Yes, I'm paying wet rates, but it does wind up costing, because they'll roll the fuel consumption into the rates that they set, and if the owner has to overhaul it soon after it goes on line, guess what isn't going to be on line much longer! Plus, if/when we get our own plane, having good habits already inculcated is a Good Thing. Courtesy ain't a bad motive, either!

But, as you say, the owner or their agent (the FBO) gets to dictate the policy.

That is definitely an issue.

Typically, if I'm requested in way contrary to what I know as good operating proceedure, I tell them "Ok, I can do that, but do know that that will set up **** condition which will eventually result in the premature failure of ***?" and then try to educate the person and introduce them to good proceedure. However, there are many people who are set in their ways regardless of how many OWTs and untruths their ways are developed from, and for them it's then, "Roger, will do it your way."

 

[wsuffa]

Got GAMIs?

With a carb?

 

[Henning]

With a carb?

See, you don't have the same engine as Bruce has, you have the same engine I had on my Travel Air. I had carb temp guages and used carb eat to smooth out the engine for LOP ops.

 

[sba55]

I experimented with LOP ops, briefly. I wasn't thrilled with performance. IIRC, in exchange for a pretty marked drop in EGT/CHT/TIT I lost 15kts (145ktas vs 129ktas, 14.1gph vs around 12.1gph). The temps looked great, but the speed was almost Sundowner-like. I may rethink that given the cost of a turbo.

There's no reason why you should loose any speed LOP vs ROP in a turbo'd engine. You'll need to increase MP to get the speed back once LOP, but that's about it.

At 75%+, Lyc. specifies NO leaning. I do run as high as 1600 degrees, redline at 1725. I had the turbo done at 1000 hours - at the same time we discovered a small crack in the wastegate pipe - there was some bearing leakage.

Lyc and Continental build good engines, but they're clueless about how to actually run them. You can lean anywhere, even at 100%, without doing any harm to the engine at all.

How much of the Advanced Pilot stuff can a renter do? I thought it involved looking at engine monitor downloads, etc. Flying the T-210 and T-182 now, I want to be kind to the engines. OTOH, I still need to respect the operations rules that the owners put down on their planes! Just because Advanced Pilot has convinced me that LOP is the right way to go, if the owner's been convinced that it's all wrong and says run ROP, I've got to run ROP as long as it's safe.

You can do all of it as a renter, too. If the owner is ignorant enough to think that LOP is dangerous, then he won't notice if you're LOP, either

-Felix

 

[Everskyward]

Flying the T-210 and T-182 now, I want to be kind to the engines. OTOH, I still need to respect the operations rules that the owners put down on their planes! Just because Advanced Pilot has convinced me that LOP is the right way to go, if the owner's been convinced that it's all wrong and says run ROP, I've got to run ROP as long as it's safe.

I flew airplanes with turbocharged engines similar to what you have in the T-210 (C-206 & C-320 with TSIO-520s) back in the days when running LOP was unheard of. I operated them as the owner requested which ended up being 60-65% power and 50-100 ROP. These planes didn't have any fancy engine temperature monitors, just an EGT so you couldn't be that accurate. Still, I flew these planes for thousands (3 or 4 thousands) of hours and can't remember having problems with the turbos. At least nothing stands out in my mind even though it was a long time ago.

 

[gprellwitz]

Well, I was looking through the logbooks the other day, and there are (or at least were) GAMIjectors on this 210. And there's definitely still an engine monitor on it. Problem is that as a renter I don't have the intimate knowledge of whats currently there that an owner has. This is towards the outer boundary of my knowledge.

 

[flyingcheesehead]

With a carb?

Bill,

I seem to recall one of Deakin's readers writing in that he was able to get a more even fuel/air distribution to the cylinders on a carbureted engine by pulling the throttle back about 1-2" of MP from wide open... Something about the throttle plate disturbing the airflow enough to make it go around better. You could give that a shot.

 

[sba55]

Well, I was looking through the logbooks the other day, and there are (or at least were) GAMIjectors on this 210. And there's definitely still an engine monitor on it. Problem is that as a renter I don't have the intimate knowledge of whats currently there that an owner has. This is towards the outer boundary of my knowledge.

There's nothing you really need to know that only the owner would know before you can run this engine safely LOP. In fact, you arguably need to know less about the engine to run LOP than to run ROP.

Since you have an engine monitor, things become even easier. Find peak EGT on the first cylinder to peak (if you're coming from the rich side). That number should remain constant no matter the power setting and it won't vary from flight to flight much, either. Then continue leaning and see what happens. If you can lean for another 20d on the _richest_ cylinder (so some of the other cylinders will be more like 40d LOP), you can run LOP at or below 70%. If you can lean even further to 70d without engine roughness, you can run LOP at 87%. If you stay at around 80% power and something like 60dfLOP, you're being MUCH nicer to your engine and the turbo than you would at 70% power and 100dfROP. And, since you're turbochanged, you won't loose any speed.

Easy way to tell %power LOP, too. Multiple fuel flow * 14.9 and you have a very accurate percent power figure. Only works LOP, though, since fuel flow and power output aren't really correlated ROP.

-Felix

 

[sba55]

Are you paying WET rates? If so, you really have no reason besides courtesy, to operate LOP.

LOP is better on your engine, wallet, but not speed.

Well, since his plane is turbocharged, it's no worse on the speed either, so why not take the savings (owner won't have to raise rates as much) and added endurance?

 

[jesse]

Well, since his plane is turbocharged, it's no worse on the speed either, so why not take the savings (owner won't have to raise rates as much) and added endurance?

Sometimes it doesn't matter how right you are--you need to run it like the owner wants it ran. I'm with Henning. Educate if you can, if not, they are the ones paying the price.

 

[sba55]

Sometimes it doesn't matter how right you are--you need to run it like the owner wants it ran. I'm with Henning. Educate if you can, if not, they are the ones paying the price.

Sure. All I was saying is that LOP doesn't mean you have to go slower. It can actually mean the opposite.

 

[wsuffa]

See, you don't have the same engine as Bruce has, you have the same engine I had on my Travel Air. I had carb temp guages and used carb eat to smooth out the engine for LOP ops.

No, I don't. He has a Continental, I have a Lycoming. They're both 360's, and they're both carrying a significant amount of power for the displacement. Bruce has a fixed wastegate, mine has a mechanical (read: single cable) direct linkage to the throttle. Bruce has modified his with a wastegate contoller - that mod is not available for mine. IIRC, Bruce's engine is six cylinders, mine is four.

Lyc and Continental build good engines, but they're clueless about how to actually run them. You can lean anywhere, even at 100%, without doing any harm to the engine at all.

As long as you watch the temps & the manifold pressure to avoid overboost. I can guarantee you, because I've watched it, that I can't lean much above 75% power without causing a temperature and rough-running problem.

Bill,

I seem to recall one of Deakin's readers writing in that he was able to get a more even fuel/air distribution to the cylinders on a carbureted engine by pulling the throttle back about 1-2" of MP from wide open... Something about the throttle plate disturbing the airflow enough to make it go around better. You could give that a shot.

Look, I'm not going to rehash the leaning argument here. Every time I talk about it, someone tells me I'm wrong.....

FWIW, the plane has a wastegate with a mechanical linkage to the throttle. Running WOT WILL result in an overboost. Max MP is about 2/3 throttle on the ground, at 19,000/20,000, full throttle will get me close to max MP for the altitude. The throttle/wastegate combo is sensitive enough that I usually let it spool up before setting power for takeoff because it is that easy to overboost. No, there's no deck controller. It ain't running at or near WOT except at altitude.

LOP at 60-75% results in a rough engine (at least at non-oxygen altitudes). I can run AT peak at 60% (meaning some cylinders are over lean, some not) without it running too rough.