Why so many top overhauls on Acclaims?

[RobertE]

i've got a J model but am lusting after an Acclaim.  I can't afford one quite yet but figure I can in a few years ( after selling the company, house,...!).  Anyway, I've started to look at what's available in 5-8 year old Acclaims and see a surprisingly consistent record of top overhauls within 400-500 hours.  What's up with that?  I fly about 125/year and sure don't want a top overhaul every 3-4 years.  Is it operator error or a fact of life with the turbocharged Continentals?

[N177MC]

Conti cylinders are crap, period.

Lycoming cylinders out last them two to one if not more ...

[DS1980]

I know it's a broad statement, and it doesn't directly answer your question, but it's most likely in the engine management techniques of the previous owners.

Also, it is more difficult to operate those deep breathing engines. If a pilot doesn't know what they are doing, they can hurt the engine very badly one time, or slowly hurt it over time. I've seen engines that needed a top at the 400-500 hour marks like you're seeing. I've seen engines with 1800 hours on them that are a thing of beauty inside. A popular thought is that Continentals burn up cylinders, and Lycomings burn up camshafts. But really, it's all on the pilot.

Have you had problems in the past with cylinders?

Edited September 12, 2015 by DS1980

[carusoam]

Take a look at TC'd and TN'd airplanes in general.  When they get used for best speed transportation the additional cost is another set of cylinders usually at the halfway point. If it is a travel tool for a private business, expect the cylinders to be worn.

when you fly like the airplane is another member of your family, LOP and CHT are your favorite topics. Cylinders can go the full TBO.

when you afford the price of an Acclaim, you get to choose...

-conservation of dead Dino's and a few cylinders.

-or-

-outright speed and climb capability.

tough choices ahead,

-a-

[carusoam]

I wrote a response that seems to have dissapeared....

it went something like this...

 

take a look at TC'd and TN'd planes in general. When they are used as traveling machines pressed into service at high power settings at high altitudes they move very quickly.

high ICPs and CHTs cause the additional wear on the cylinders.  This can be considered normal wear and tear for the greatness of fabulous climb rates and wonderous ground speeds.

the good news, you can still fly conservatively (LOP and CHTs) and preserve your cylinders. Or, you fly the cylinders off it with sustained climb rates over 1500 fpm to the FLs and GS over 200kts...

I went with the NA O for the same logic.  I am an LOP guy.  I expected that a set of cylinders could be in the future, but knew that LOP and good CHT monitoring/management can make them last.

go acclaim!

-a-

Edited September 12, 2015 by carusoam

[DS1980]

I see the first Mr. A. Both look good.

Edited September 12, 2015 by DS1980

[markfoster7700]

Yes, this is not just a case of "crappy Continental" cylinders.  I flew a Debonair IO-470-N.  I went through 3 engines, all to TBO and well beyond TBO and never had a cylinder off of the plane, and never had any compression test less than 65/80 -- most were in the 70's for the life of the engine.  I now fly an Ovation 3 that I bought new in 2008 and have flown it for 1400+ hours with no removal of any cylinders and compressions all in the upper 60's to mid 70's.  It has a lot more to do with how often you fly and at what power settings than whether is is a Continental or a Lycoming. 

Having said that, this situation was due to the fact that the Acclaim engine started out life with the crank case breather venting into the exhaust, and thus coking up the cylinders from the backside.  This caused them to need to be topped at about 400 hours.  I understand that there is now a mod for an air/oil separator that fixes the problem.  Sorry that I don't have a link handy.

[PMcClure]

Can't find the reference, but there was some ad/sb or other ? on acclaims whereby ... sketchy memory ... the oil breather tube or something was getting coked up with cooked oil (blocked or restricted) due to placement(?), thus pressures within the crankcase were getting out of spec and contributing to poor cylinder lubrication ... (?).  Lot of question marks, but I read something on this somewhere.

I wrote this after talking with TCM. I can't find the thread but this was the fix. There was some discussion about who paid for what, but I recall there was some warranty from TCM or Mooney.

 

[M20F]

You see a lot of Cirrus's with tops as well.  In my book it is engine management.  If you use the right power settings, lean (ROP/LOP/PEAK) correctly, and ensure the cylinders don't get too hot or cold you don't have issues.  Do it wrong and it is real easy to burn them up. 

[DonMuncy]

I have an opinion based on very little information. I believe that some turbo planes are bought by people who are not really well versed in engine operations. Some seem to think that if the M20x is advertised to be able to fly at y airspeed, they should be able to push the throttle to that speed and leave it there. I also believe that for whatever reason, Continental cylinders often (temporarily) have low compression figures and are replaced unnecessarily. I am not saying that they last as long as they should; just that they are not as bad as their reputation.

[RobertE]

I wrote a response that seems to have dissapeared....

it went something like this...

 

take a look at TC'd and TN'd planes in general. When they are used as traveling machines pressed into service at high power settings at high altitudes they move very quickly.

high ICPs and CHTs cause the additional wear on the cylinders.  This can be considered normal wear and tear for the greatness of fabulous climb rates and wonderous ground speeds.

the good news, you can still fly conservatively (LOP and CHTs) and preserve your cylinders. Or, you fly the cylinders off it with sustained climb rates over 1500 fpm to the FLs and GS over 200kts...

I went with the NA O for the same logic.  I am an LOP guy.  I expected that a set of cylinders could be in the future, but knew that LOP and good CHT monitoring/management can make them last.

go acclaim!

-a-

This is very helpful.  So what speed at, say, 18K feet running LOP and exercising good engine management should one expect?  (i run my J LOP all the time and gladly surrender 5 knots to do it).

[DonMuncy]

You don't pick a speed. You fly at 70 to 75% power per the POH, and take whatever speed you get. There are significant differences between individual planes.

[mike_elliott]

Can't find the reference, but there was some ad/sb or other ? on acclaims whereby ... sketchy memory ... the oil breather tube or something was getting coked up with cooked oil (blocked or restricted) due to placement(?), thus pressures within the crankcase were getting out of spec and contributing to poor cylinder lubrication ... (?).  Lot of question marks, but I read something on this somewhere.

Your memory is correct. A good shop like Maxwell will clean this every annual on an Acclaim. Roger Gradle from Continental had a good bit to say on this at the first Mooney Summit. Neal George might contribute something about it in a couple of weeks at the next Mooney Summit.

[Joe Zuffoletto]

I'm not an engine guy, but the breather tube came out of the factory poorly designed and that's what was cooking the cylinders. There is a known fix. My Acclaim had about 220 hours on it when I purchased it, the cylinders were all fine, and I had Arapahoe Aero apply the fix immediately. Now, at around 450 hours or so, my engine still purrs like a tiger and the cylinders are still in great shape.

To Don Muncy's comment: Shortly after purchasing my Acclaim I went on an extended test flight with Bruce Jaeger up in Willmar, MN. Our goal was to establish healthy regimes for ROP and LOP operations based on the nuances of my specific copy of the engine. Bruce knows a lot about these engines and how to keep them healthy. After extensive experimentation, we arrived at simple-to-remember setups for ROP and LOP cruise; I just pick the one I want based on my mission that particular day.

I made a point to do all this because I never did it in the 11 years I had my Encore; nor did I have much of an engine monitor in that plane, and my cylinders paid the price (had to get it topped at about 1,000 hours, as I recall). I learned my lesson the hard way.

[M016576]

The following is my opinion... But backed up by your stats (ie most need top overhauls).  It is somewhat aligned with Don's post above, too.

A typical Turbocharged engine will require top overhauls.  The reason?  The motor is capable of creating more power and more heat.  The materials used are the same as a NA engine.  More stress can then be imparted upon the motor for longer periods of time due to the extra energy the motor can develop.

can the motor be run without top overhauls? Yes.  But the question you need to ask yourself is- Do you have the discipline to run the motor at a reduced power setting in an effort to save cylinders?  The statistics you quote would say most don't...

[kortopates]

I believe Don and M016576 covered this and Joe as a long time turbo operator validates it. Bottom line is that majority of people that buy a new or late model Acclaim buy them because they are the fastest single engine piston plane available. They didn't spend all that money to go slow. Secondly recognize maximum performance cruise tables in the POH are based on maximum performance and fuel economy to a certain extent for range. But it should be obvious that maximum performance and engine longevity are very much at odds with one another; especially obvious when you look at your POH engine limitations that allow CHTs up at 450 and TITs 1650+. If you want to operate for maximum engine longevity you will need to give up seeking the speed records you know your aircraft is capable of and reduce power levels below max cruise to more conservative levels closer to 70% or less and then further enrichening the mixture beyond the POH tables for ROP settings (which are typically saying lean to peak - about the worst place to operate your engine at high power cruise if you care about longevity) or running more LOP at high power settings. Bottom line is to operate it in such a fashion your engine never experiences thermal stress.

Note that Mike B more than doubled his TBO time on his Continental TSIO-520's before he topped his engines just recently with two thirds of his cylinders being original. Still think its just crappy cylinders?

Edited September 12, 2015 by kortopates

[RobertE]

You don't pick a speed. You fly at 70 to 75% power per the POH, and take whatever speed you get. There are significant differences between individual planes.

Well, I don't have an AcclaimPOH so is there someone who does who could tell me likely true airspeed at 70% power at, say, 18K - 20K?  (With the recent.apparent hypoxia deaths @ 25K I'm a little reluctant to put full faith in my oxygen system at an altitude at which a problem has only minutes to fix).  Thanks.

[M20F]

Well, I don't have an AcclaimPOH so is there someone who does who could tell me likely true airspeed at 70% power at, say, 18K - 20K?  (With the recent.apparent hypoxia deaths @ 25K I'm a little reluctant to put full faith in my oxygen system at an altitude at which a problem has only minutes to fix).  Thanks.

http://www.deltaaviationllc.com/Nav%20Page/acclaim/acclaimAFM.pdf

[DonMuncy]

Well, I don't have an AcclaimPOH so is there someone who does who could tell me likely true airspeed at 70% power at, say, 18K - 20K?  (With the recent.apparent hypoxia deaths @ 25K I'm a little reluctant to put full faith in my oxygen system at an altitude at which a problem has only minutes to fix).  Thanks.

Sorry, my answer sounded like a smarta**. It would have only been appropriate if you already had an Acclaim and wanted to know how fast to fly it. Not too likely a scenario. I don't have an Acclaim. Someone will probably jump in and give you a more appropriate answer.

[M016576]

Well, I don't have an AcclaimPOH so is there someone who does who could tell me likely true airspeed at 70% power at, say, 18K - 20K?  (With the recent.apparent hypoxia deaths @ 25K I'm a little reluctant to put full faith in my oxygen system at an altitude at which a problem has only minutes to fix).  Thanks.

that's a valid point: if you're planning on spending any real time at 25K, a backup O2 system is probably prudent.  if I recall correctly, TUC (time of useful consciousness) at 25K for an average healthy adult in their 30's is around 2 minutes.  at 18K it's about 30 minutes.  A couple other threads have touched on this- but if you're older, or work out "less than average" then you're TUCs fall off pretty quick...

[carusoam]

The IO550 in a long body likes 175kts ROP and 165kts LOP at WOT and 11,000’.  Equating to 15gph and 13gph, roughly speaking.  Climbing using the blue box EGT and Running LOP my cylinders went as long as the engine did. I swapped out a little early to get the 310hp, TopProp, N engine.  I went from fearing changing cylinders to swapping out a completely usable system a few years later....

expect that hat you can mimic the O's performance pretty easily with a TN'd version of the same engine.  

Again, air cooling becomes different at altitude as the air resistance becomes lower.

it becomes a real personal battle to hold back the reigns when it is so easy to add the power.

on the other topic...

the requirements for O2 are a bit funny.  Modern technology allows us to have dual systems that take over or back-up automatically.  Old technology suggests a secondary back-up system.  

If you only have two minutes, there is barely enough time to identify the situation, never mind fire up the back up system in the time you have left. Emergency descent under manual control won't be a complete solution either...

the Long Body has a bunch of Charlie weights that can be substituted for a second installed O2 system if you want.

time of useful consciousness is an incredibly helpful piece of knowledge to have if you are confronted with that situation.  Something I learned at Mooney Space...

best regards,

-a

Edited September 13, 2015 by carusoam

[THill182]

Well; I used to have a Cessna 182RG with a Lycoming O540; which was bullet proof. Nothing ever went wrong with that engine no matter how I ran it, and if you look on ASO or Controller, you will find many 182RG's with 2400 hours on the engine (TBO is 2000)..

Then I transitioned to an Ovation. I flew it according to the handbook, and quickly burned up the engine. At about 600 (200 of which I put on; the previous owner also used the POH settings and 75% power), all cylinders needed to be replaced (two had been replaced before then), because of cracks running from the injectors to the spark plugs. Also, before that, oil consumption started to increase.

 

Since then I have learned to fly at 65% power, and LOP, watching CHT's. I haven't had any engine problems related to cylinders for a few years now, and compression looks great.

 

I would echo the other comments: It is tempting to run these engines at full (75%) power as "advertised".. But it is better to look at long-body Mooneys as efficient travel machines, where you get good speeds (not the advertised 200kts etc.) with miserly fuel consumption LOP. I routinely see 165 to 175 kts between 8000 ft to12,000 ft, LOP burning 12 to 13 gph -- not shabby (plane has air conditioning and TKS -- both slow it down significantly; I would expect others to get 5 to 10 kts more..).

 

I have no experience with turbocharged planes. But the lesson I have learned is that the IO550 needs to be babied. That is very different from the Lycoming O540 that I used to fly.

[N177MC]

 I have learned is that the IO550 needs to be babied. That is very different from the Lycoming O540 that I used to fly.

This is pretty typical, hence my comment that Conti cylinders are cr@p COMPARED to Lycomings  ...

[Guest]

This is pretty typical, hence my comment that Conti cylinders are cr@p COMPARED to Lycomings  ...

It could explain why RAM uses new nickel plated cylinders on their engine overhauls.

Clarence

[aviatoreb]

There has been a lot said here that you need to run a conti conservatively to make tbo with the cylinders - and also that the cylinders are crap and that turbos are implicated.

Here is the real story that I have gathered by reading many sources but I will just summarize what I read - and my own direct observation - rather than trying to track down all the sources.

Continental designed a superb engine.  It runs great.  They used to build a great engine but sometime about 20 or 15 years ago they went cheap and made personnel changes that resulted in a much lower quality build.  Specifically relevant to this discussion, they no longer put the care into building cylinders that they should - and the valve assembly was a weak point.  Those valves were not seating well direct from the factory when new.  I read from beechtalk this statement, and he (I forgot which one but it was one of the guys who runs the GAMI-APS program) said that when you have a cylinder with a crappy built valve assembly gasses will leak by and no matter how you run the engine, conservatively, LOP, ROP, or not, you will need to overhaul that (and others too) cylinder by 1000 hrs at least.

So - what do you know - my own engine started showing two bad cylinders at 980 hours - right on schedule (3 years ago ago).  I only owned and operated my airplane since the engine had 750hrs.  It had gone from all good signs and compressions in the low 70s to one very weak cylinder (in the 20s) and one with singificant blow-by sounds and compressions in the 50s.  So overhaul those two at least was called for.  When we got those two cylinders off - I was appalled to see the workmanship on those cylinders.  They were just not seating very well - just like I read from numerous sources.  ANd this is not an issue of it wearing out - this is how it was built- built poorly.  So I decided right there to do a top since i then suspected the other cylinders were probably built the same poor standard.  I decided to buy new cylinders (from a company other than continental since I was mad at them - but in retrospect, that doesnt matter) and furthermore, I decided to have the valves worked by an expert cylinder guy to seat nice and tight (called lapping).  That last step, I will do with every overhaul or cylinder to be installed in my engine henceforth - a little extra spent up front can save I think down the road. 

So that's the main thing for the fleet of conty engines - leaking hot exhaust gases past poorly built valve cylinders directly from the factory.  IF YOU HAVE A POORLY BUILT cylinder - there is NOTHING you can do from the pilot seat that will make that cylinder go to tbo.  This applies to turbo or NA.  According to the material I read by the GAMI-APS guy on beechtalk - he said that even a conservatively operated engine that has a poorly built cylinder with a poorly built valve assembly will not go the distance.

My own continental engine now has about 400 hours on the new cylinders and all compressions were 77 or higher at last check - knock on wood.  The rocket is very easy to keep the cylinders cool - that is the temps are easy to maintain at <380F CHT at all times.  This is one factor in the pilot operating that can help so I hear and I am working hard on it.

They say its controlling CHT's and also ICPs that make cylinders last.  Both of those are controllable by the pilot by knowing how to operate the red knob. And not going crazy with the black knob.  This is true whether its conty or lycosaurus.  But as I said, it also takes a properly built cylinder in the first place and conty for a long stretch had a major workmanship problem in the valves department (supposedly that is fixed now on their factory floor - but I will still be reworking any valve assembly that goes installed into my airplane, new or not).

The Acclaim problem is none of the above, according to the AD, as already stated - it has a special problem related to coking of the breather - a fixable problem.  Once that is fixed, then it will be subject to all the 3 problems above (1) CHTs - keep em under control with the red knob and pitching for enough speed and step climbing if you need (2) ICPs - high power leads to higher chts but also stress on the cylinders - and high power in the winter may not lead to high temps but still high icp - also the red knob controls where in the power stroke (angle) the combustion occurs and that has cht and icp implications.  (3) valves need to be built right and there is nothing the pilot can do about operating the airplane out of this gotcha- only the pilot-owner can fix this by making sure only good valves are in the plane.