Proximity to overhaul?

[lalib]

Looking at purchasing an Acclaim Type S with 1,390 hours. Just starting to do research and it seems like the engine rarely runs to or beyond TBO. Would love to hear opinions and any feedback on how price should be affected based on the total time.

[KSMooniac]

Welcome.

Many (most, all?) Continental engines from the last 20 years or more seem to have trouble with cylinders, so it is not uncommon to see top overhauls/cylinder replacements done between 700-900 hours.  The lower ends seem to do just fine with regular use and oil changes.  There is lots of speculation on the cause of cylinder troubles, but the most credible sources in my 15+ years of avid reading point to improper factory installation of valves and guides.  Some will say LOP or ROP ops cause it, but that does not ring true IMO.  There is far more experience operating these engines over on Beechtalk, along with some data and direct source data from folks that really know.  I am NOT an owner/operator of a Continental, but I believe everything I type here could be confirmed by any number of experts you'll query.  One expert engine shop that has a stellar reputation amongst the big Continental engine base has routinely stated that he will disassemble new-in-the-box Conti cylinders and re-work the valves to his standards, and after that, they'll make a full TBO run, or more.

As far as valuation, the simple answer is to ratio the TSMOH to the TBO and compare to a field overhaul, factory overhaul, or factory new price of your choosing and add that to the value calculation you do for that particular airplane.  There are far fewer Acclaims in the wild as compared to J's like mine, so the equipment and option variations will be much smaller.  I believe your options might be STEC55X vs. GFC700 autopilot, WAAS or not, Type S or not (your candidate obviously is), A/C, O2, TKS, and perhaps a 310 hp upgrade.  Then you consider hours, damage history, maintenance history, etc.  I don't know what a base price for an Acclaim might be, and I do not know if Jimmy Garrison (GMAX principal partner) has published a valuation guide for that model. VREF may be helpful.  16.5 years ago when I bought my J, I kinda did my own with knowledge gleaned from daily ad searches, Jimmy's guides, etc. and am happy with what I did.  

For your specific candidate, it appears to be loaded with the exception of A/C, and I believe that Mooney quit allowing A/C with TKS (wisely) due to useful load limitations.  I'd say it was a 700+k plane new, and they're not making any more now so factor that into your valuation.  It's got everything else... primo autopilot, WAAS, etc.  I would ask for engine records and engine monitor data to see how hot it has been running, and if cylinders have been changed already.  If not, you might plan to do a top overhaul and then fly it another 1000 hours, even past TBO.  Or if you're an experienced owner you might fly it until the engine indicates it needs attention, and then overhaul it to your specs at your favorite shop.  That is what I would do as an experienced owner vs. rolling the dice with a factory engine, but I'm weird that way.

[lalib]

29 minutes ago, KSMooniac said:

Welcome.

Many (most, all?) Continental engines from the last 20 years or more seem to have trouble with cylinders, so it is not uncommon to see top overhauls/cylinder replacements done between 700-900 hours.  The lower ends seem to do just fine with regular use and oil changes.  There is lots of speculation on the cause of cylinder troubles, but the most credible sources in my 15+ years of avid reading point to improper factory installation of valves and guides.  Some will say LOP or ROP ops cause it, but that does not ring true IMO.  There is far more experience operating these engines over on Beechtalk, along with some data and direct source data from folks that really know.  I am NOT an owner/operator of a Continental, but I believe everything I type here could be confirmed by any number of experts you'll query.  One expert engine shop that has a stellar reputation amongst the big Continental engine base has routinely stated that he will disassemble new-in-the-box Conti cylinders and re-work the valves to his standards, and after that, they'll make a full TBO run, or more.

As far as valuation, the simple answer is to ratio the TSMOH to the TBO and compare to a field overhaul, factory overhaul, or factory new price of your choosing and add that to the value calculation you do for that particular airplane.  There are far fewer Acclaims in the wild as compared to J's like mine, so the equipment and option variations will be much smaller.  I believe your options might be STEC55X vs. GFC700 autopilot, WAAS or not, Type S or not (your candidate obviously is), A/C, O2, TKS, and perhaps a 310 hp upgrade.  Then you consider hours, damage history, maintenance history, etc.  I don't know what a base price for an Acclaim might be, and I do not know if Jimmy Garrison (GMAX principal partner) has published a valuation guide for that model. VREF may be helpful.  16.5 years ago when I bought my J, I kinda did my own with knowledge gleaned from daily ad searches, Jimmy's guides, etc. and am happy with what I did.  

For your specific candidate, it appears to be loaded with the exception of A/C, and I believe that Mooney quit allowing A/C with TKS (wisely) due to useful load limitations.  I'd say it was a 700+k plane new, and they're not making any more now so factor that into your valuation.  It's got everything else... primo autopilot, WAAS, etc.  I would ask for engine records and engine monitor data to see how hot it has been running, and if cylinders have been changed already.  If not, you might plan to do a top overhaul and then fly it another 1000 hours, even past TBO.  Or if you're an experienced owner you might fly it until the engine indicates it needs attention, and then overhaul it to your specs at your favorite shop.  That is what I would do as an experienced owner vs. rolling the dice with a factory engine, but I'm weird that way.

Thanks for all the information and wisdom there. It's a Type S with TKS, no A/C, O2, GTX 345R, WAAS, GFC 700, 280 HP. Compressions were in the mid to high 60s, which the seller claims is typical.

Edited August 1, 2023 by lalib

[KSMooniac]

Continental will tell you the raw compression test number is only part of the story, and that a borescope should be used before any action is taken.  These days, $200 or less will buy a very capable unit suitable for checking the valves.  If you advance to a pre-purchase inspection, I would have the mechanic perform a compression check and borescope eval of each cylinder.  Deposit patterns on the exhaust valves will tell the story easily... if they're all round/concentric then those cylinders might be doing just fine and make it to TBO.  If you see irregular deposits, then the valve is not seating correctly, and you can count on it needing attention soonish.

[Danb]

2 hours ago, lalib said:

Thanks for all the information and wisdom there. It's a Type S with TKS, no A/C, O2, GTX 345R, WAAS, GFC 700, 280 HP. Compressions were in the mid to high 60s, which the seller claims is typical.

If you haven’t checked the engine logs get a copy from Mark to see if a top or any cylinders were replaced and inquiry if the sb was done and what type oil separator is installed. Most early acclaims had issues which subsequently resolved somewhat. The plane referenced is gorgeous with the gray bandit paint scheme. I purchased my Acclaim at mid 300 hour range and had it topped prior to purchase, there’s an Acclaim a couple hangers down from mine for sale for $665,000 at 520 hours he just had a complete top done. As Scott mentioned have the valves and cylinders examined by a professional great plane suspect engine I’m a strong and of Lycoming though.

[Fly Boomer]

On 7/31/2023 at 6:17 PM, lalib said:

Would love to hear opinions and any feedback on how price should be affected based on the total time.

Pursuant to posts from @KSMooniac and others above, if you already own an airplane, or you are certain you will, buy the Vividia VA-400 version 5 borescope.  And get the Apple WiFi box if you are an iPad user.  I'm a Mike Busch acolyte, and he got 5,000 SMOH on one of the big-bore Continentals on his 310.  He is generally opposed to pulling cylinders unless there is no other alternative.  That said, he considers cylinders to be a disposable accessory like an alternator or mag, and only advocates splitting the case when it starts talking to you.  If engine monitor data shows that cylinders have been kept below 380, they may go the distance.  More than that, they won't.  

[Geoff]

FYI new TSIO 550-G with core exchange