acclaim s

[pkofman]

can someone tell me what the compressions should be on an acclaim "s" to be considered " normal" if there is such a thing

airplane approx 2015 and 400 hours... what would be considered normal or healthy 

Im not meaning to ask such an open ended question with a gazillion variables and permutations..

rather ....Just some idea of a range if possible would be helpful

Peter

[Schllc]

You’re going to get a lot of answers to that question, because it’s a little open ended. 
If I was buying the airplane, assuming it is flown regularly and the compression check is done properly, I would want to see nothing below the mid 60’s.   That doesn’t mean something in the 50’s is unacceptable. But it would also be important to look at the logbooks to see if anything lower was a trend or an anomaly. 
I believed continentals “limit” for when it isn’t airworthy is the high 30’s.  
I actually saw this on a prebuy one time. Compression check revealed high 30’s on one cylinder  They borescoped it, everything looked good so the guy took it up, ran it hard for 15 minutes, and it was making full power.  He landed, rechecked and it was in the low 60’s.  He has been flying the plane regularly for the last few years without changing a cylinder  

I personally believe some(not all) of these cylinder issues are overly cautious owners and A&P’s  

 

[GeeBee]

Continental SB03-3

https://www.aircraftspruce.com/catalog/pdf/servicebulletin.pdf

 

[Cruiser]

Didn't Continental run an engine to nearly full power without ANY rings in the pistons? 
Compression is an indicator, I would be more concerned about WHY compression is low and deal with that problem. 

 

[Niko182]

On the TCM engine you really want to look at the valves. That tends to be where the issues lie on the engines. As others have stated, the compressions tend to drop off pretty quick as the engines gain time, at least compared to a lycoming. FWIW, I've had a cylinder come back with a 0/80 compression. I have no idea how long I was flying it like that, and there was no indication that one of the cylinders was bad. EGTs and CHTs were normal in flight and I had no issue flying LOP. If anything falls under 50 I'd look into it, but I wouldn't veto an airplane because of it. I bought my eagle with compressions as low as 42.  That engine went from 1350 hours to 2050 hours and was new in 99. After flying it consistently, they all came back above 60. I will say on the acclaim you are significantly more likely to have to do a top on it mid way, so i'd keep that in mind.

[GeeBee]

46 minutes ago, Cruiser said:

Didn't Continental run an engine to nearly full power without ANY rings in the pistons? 
Compression is an indicator, I would be more concerned about WHY compression is low and deal with that problem. 

 

Actually what they did was file the ring ends down so finally ring gap was so large compression was zero. The engine turned up full horsepower. As a result of that an other research, TCM issued SB03 which really was a watershed event in aircraft maintenance. I agree the "why" is more important than the "what" and sometimes low compression is a transitory event, which is why they say to "fly it" then check again.

[1980Mooney]

Per Mike Busch:

"The fundamental message of SB03-3 is that the compression test is not a reliable way of assessing cylinder condition, and that the borescope inspection is much more reliable. If a jug flunks the compression test but looks good under the borescope, then the compression measurement must be considered suspect, and heroic measures should be taken to raise it before a decision is made to pull the jug."

EAA_2013-07_compression-in-context.pdf (savvyaviation.com)

 

[Schllc]

3 hours ago, Niko182 said:

On the TCM engine you really want to look at the valves. That tends to be where the issues lie on the engines. As others have stated, the compressions tend to drop off pretty quick as the engines gain time, at least compared to a lycoming. FWIW, I've had a cylinder come back with a 0/80 compression. I have no idea how long I was flying it like that, and there was no indication that one of the cylinders was bad. EGTs and CHTs were normal in flight and I had no issue flying LOP. If anything falls under 50 I'd look into it, but I wouldn't veto an airplane because of it. I bought my eagle with compressions as low as 42.  That engine went from 1350 hours to 2050 hours and was new in 99. After flying it consistently, they all came back above 60. I will say on the acclaim you are significantly more likely to have to do a top on it mid way, so i'd keep that in mind.

I think this is more hangar talk now than reality.  There was a coking issue with the very first two years of acclaims that caused backpressure issues, that has long since been resolved and mid time top it is certainly not a rule.  I would also submit that is completely a function of how the plane/engine is flown/treated.

I have flown with people who have zero indication that they understand even the basic concept of an internal combustion engine, much less a turbo charged aircraft engine.

[Mooneymuscle56m]

I have a 2007 Acclaim that is on its third set of cylinders in 1600 hours.  I purchased at 1020 hours and had the last top at 865 hours.  I am still looking good, burns a qtr every 7-8 hours and lowest compression is 68.  
 
I will do one more top before Lycon gets it.

[carusoam]

Full Flaming dragon mode?

Or a mix of ROP and LOP?

The cost of flaming dragon mode is sets of cylinders….

The advantage of LOP all the time…. Cylinders go the distance..

Tough choices….   

Best regards,

-a-

[StevenL757]

9 hours ago, Mooneymuscle56m said:

I have a 2007 Acclaim that is on its third set of cylinders in 1600 hours.  I purchased at 1020 hours and had the last top at 865 hours.  I am still looking good, burns a qtr every 7-8 hours and lowest compression is 68.  
 
I will do one more top before Lycon gets it.

Echoing @carusoam, 

With top overhauls done that frequently I assume it has - and continues to be flown - ROP?

Edited January 17, 2023 by StevenL757

[Guest]

9 hours ago, StevenL757 said:

Echoing @carusoam, 

With top overhauls done that frequently I assume it has - and continues to be flown - ROP?

There has to be more to it than RoP operations.  Many other TCM engines have been run RoP their whole lives and not had that many cylinder issues.

[Schllc]

I don’t think rop alone would be the cause either. 
I think the early acclaims had a coking problem that contributed to a lot of the early tops. 
I would bet a lot of the others are people just wringing them out at max mp, max rpm which means higher temps everywhere. 
I suspect a lot of tops are overly conservative maintenance. In the case of 98FL there were also four prop strikes and a period of sitting idle for over a year somewhere in the midst of those four tops. 
lastly, how does that old adage go, unhappy customers talk to 1000 people and happy ones talk to 10. 
I think we are very likely to hear all the bad stories but the happy guys are just flying along. 
I know several  acclaim owners pretty well, some of the planes I’ve owned and none of them had had any tops done and only one has even had a cylinder changed. 
I’ve flown with people that never once looked at power settings, temps etc. they just fly it like a flight school 172. you wouldn’t think an airplane owner would be so oblivious, but they are more common than you think. 

[Danb]

I’m currently looking at a 2016 acclaim whose compressions have been in the 60’s since new or the first annual. I’m not sure whether to look elsewhere or figure that’s normal. I’ve looked at logs on about 7-8 acclaims and the compressions are much more inconsistent than those on lycoming. Being not very mechanical savvy not sure if there’s issues with acclaims or not. I’m aware of the coking issues predominantly on the 2006 and 2007s 

[Danb]

Also does anyone have a copy of the acclaim POH 

DB

[Niko182]

https://s0c174270dcfbf85f.jimcontent.com/download/version/1551389156/module/8272340815/name/M20V_POH.pdf

[Schllc]

1 hour ago, Danb said:

I’m currently looking at a 2016 acclaim whose compressions have been in the 60’s since new or the first annual. I’m not sure whether to look elsewhere or figure that’s normal. I’ve looked at logs on about 7-8 acclaims and the compressions are much more inconsistent than those on lycoming. Being not very mechanical savvy not sure if there’s issues with acclaims or not. I’m aware of the coking issues predominantly on the 2006 and 2007s 

Those compressions wouldn’t turn me off a bit if it makes full power and wasn’t part of a trend downward. 
if it’s flown regularly, has good mxrecords it wouldn’t  bother me.
but it’s a convenient way to hit a sell over the head and most mechanics would be unwilling to be positive about it which adds to anxiety. 

[carusoam]

Dan may not be familiar with Continental compression compared to Lycoming compressions…

different orifice and procedures… different numbers, lower than Lycoming…. And harder to get good readings…

Good news…  there is time to become familiar with the Continentals…

I had the same concerns when looking at a Missile just prior to being blessed with the O…   
 

ROP + High Power output = High CHTs in thin air…  

aka flaming dragon mode…  

the POH says you can fly this way… just your wallet says you may want to reconsider that a little bit…

 

Go Acclaim!

 

Best regards,

-a-

[Guest]

12 hours ago, Danb said:

I’m currently looking at a 2016 acclaim whose compressions have been in the 60’s since new or the first annual. I’m not sure whether to look elsewhere or figure that’s normal. I’ve looked at logs on about 7-8 acclaims and the compressions are much more inconsistent than those on lycoming. Being not very mechanical savvy not sure if there’s issues with acclaims or not. I’m aware of the coking issues predominantly on the 2006 and 2007s 

Pretty typical numbers for a 550.

[Z W]

I've wondered... are Acclaim owners just more likely to just say, "Top the engine"?  That would explain why many of them listed for sale show a recent top overhaul, which many owners here then believe is a sign of a problem with the engine or its operation.  Maybe it's not.

Thinking being, the Acclaim owners represent those who paid the most for their Mooneys, and are likely the least concerned with costs of repair and maintenance.  Bad compression reading at annual?  Put all new cylinders on it.  I want it ready to go and not down for more cylinders again at next annual.  Only slightly more time down for a top overhaul than to do the one failed cylinder.

We've put several new cylinders on our M20K over the years.  Always due to low compressions at annual, and at the mechanic's recommendation, never due to abnormal temperatures or engine performance.  I just read SB03-3 for the first time, and now feel misled.  Never once were we asked to go fly it for 45 minutes so they could re-check the cylinder, or shown borescope photos of a problem inside the cylinder.  I suspect many Acclaim owners, and other plane owners, have been treated the same.

[DonMuncy]

3 hours ago, Z W said:

I've wondered... are Acclaim owners just more likely to just say, "Top the engine"?  That would explain why many of them listed for sale show a recent top overhaul, which many owners here then believe is a sign of a problem with the engine or its operation.  Maybe it's not.

Thinking being, the Acclaim owners represent those who paid the most for their Mooneys, and are likely the least concerned with costs of repair and maintenance.  Bad compression reading at annual?  Put all new cylinders on it.  I want it ready to go and not down for more cylinders again at next annual.  Only slightly more time down for a top overhaul than to do the one failed cylinder.

We've put several new cylinders on our M20K over the years.  Always due to low compressions at annual, and at the mechanic's recommendation, never due to abnormal temperatures or engine performance.  I just read SB03-3 for the first time, and now feel misled.  Never once were we asked to go fly it for 45 minutes so they could re-check the cylinder, or shown borescope photos of a problem inside the cylinder.  I suspect many Acclaim owners, and other plane owners, have been treated the same.

Anyone with a Continental engine, or any one considering a Continental should read this three times. My engine had multiple (almost certainly unnecessary) cylinder changes in its life. I am ashamed to admit at least one of them was on my watch.

[exM20K]

16 hours ago, Danb said:

Also does anyone have a copy of the acclaim POH 

DB

If you're a foreflight performance plus or higher subscriber, you can download the performance profiles which are built from the POH.  With TKS, I back the speeds off 5%.

For W&B, My plane (TKS, No A/C) is

 

Basic Empty CG (in)  45.518

Basic Empty Weight (lbs)  2490

 

The 310 HP Acclaim Type S was built off my poh.

-dan

[Will.iam]

I think it just boils down to what you don’t know will cost you. we were told 50 ROP was best compromise for power and efficiency and we operated there until we found out 50 ROP was also the worse possible mixture to operate your engine at high power setting because of the higher cylinder temps it caused which we now know causes longevity issues. This is the same as compression below 60 was considered bad and needed to be replaced one assumed max HP was affected. Only after continental did tests showing max HP was able to be achieved with compression readings as low as 40 and that piston rings could sometimes line up in such a way to cause unusually low compression readings after engine shutdown did we finally receive guidance to run the engine again and recheck the values.  Thus a single compression reading alone is not a good proxy to cylinder health, but is a good way to upsell a new cylinder to an unknowledgeable owner. 

[mike_elliott]

18 hours ago, M20Doc said:

There has to be more to it than RoP operations.  Many other TCM engines have been run RoP their whole lives and not had that many cylinder issues.

If the crankcase vent sb m20-319 hasnt been done, it would explain the carnage of cylinders.

[Schllc]

8 hours ago, Z W said:

I've wondered... are Acclaim owners just more likely to just say, "Top the engine"?  That would explain why many of them listed for sale show a recent top overhaul, which many owners here then believe is a sign of a problem with the engine or its operation.  Maybe it's not.

Thinking being, the Acclaim owners represent those who paid the most for their Mooneys, and are likely the least concerned with costs of repair and maintenance.  Bad compression reading at annual?  Put all new cylinders on it.  I want it ready to go and not down for more cylinders again at next annual.  Only slightly more time down for a top overhaul than to do the one failed cylinder.

We've put several new cylinders on our M20K over the years.  Always due to low compressions at annual, and at the mechanic's recommendation, never due to abnormal temperatures or engine performance.  I just read SB03-3 for the first time, and now feel misled.  Never once were we asked to go fly it for 45 minutes so they could re-check the cylinder, or shown borescope photos of a problem inside the cylinder.  I suspect many Acclaim owners, and other plane owners, have been treated the same.

This^^^^^^^^
x 10000