New to the Ovation / IO-550

[MJHarm]

**Note: I’m editing this topic somewhat because I originally posted with a question about high CHTs. I’ll leave the original question below for context as there’s some good discussion as a result but to clarify, I’ve since talked with the pilot that I flew with and realize that I picked up the wrong data. Unfortunately, this stirred up some well-founded concern for the engine. So with a bit of egg on my face, I want to redirect the conversation a bit and ask for any tips or gotchas to look out for in the prebuy/early ownership and I’d be interested in your take on what improvements would bring the best value.

I’m in the process on a 98 Ovation w/ an IO550G (no STC), speed brakes, O2, factory AC, steam gauges, a Garmin 750/430/345 and a KFC150 AP.

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All,

I’m finally getting back to aircraft ownership after a long hiatus. Previously owned a ‘68G which I loved and flew all over the East Coast. I recently test flew an Ovation and was surprised at the high CHTs throughout the flight. It was a summer morning flight in the SouthEast but the temps were approaching 500. 
What should I expect to see?

Edited July 7 by MJHarm
Topic correction

[Niko182]

8 minutes ago, MJHarm said:

All,

I’m finally getting back to aircraft ownership after a long hiatus. Previously owned a ‘68 G. I recently test flew an Ovation and was surprised at the high CHTs throughout the flight. It was a summer morning flight in the SouthEast but the temps were approaching 500. 
What should I expect to see?

You should not expect to see anywhere near that. Improperly timed mag, old baffles, too low of a fuel flow on climb out, old inaccurate probes, or a combination of it all or the old JPI . I'd guess combination of some of those. I see 390 in the climb out sometimes but rarely, if I'm climbing at a lower IAS to climb faster and its hot outside. The worst I've ever seen was 410 for about a moment leaving Palm Springs in the middle of summer when it was 118 degrees outside. I climbed at a lower IAS because I just wanted to get high out of the heat and was willing to let the CHT get a little hotter because of how hot it was in the cabin. You should not ever see 500 in a continental. I'm fairly certain 460 is the max for continental, and anything higher has the chance of causing damage to the aircraft. Which plane was this if you don't mind me asking?

[MJHarm]

Thanks. Good info. Sure, N46BA.  Advertised in Trade-A-Plane.  Any inside info would be appreciated. 

Edited July 7 by MJHarm
Grammar

[Fly Boomer]

34 minutes ago, MJHarm said:

temps were approaching 500. 
What should I expect to see?

With those temps, that airplane can expect to see a top overhaul in the very near future.  No idea what the POH says, but Mike Busch says 380 for decent cylinder life.  

[NickG]

3 hours ago, MJHarm said:

All,

I’m finally getting back to aircraft ownership after a long hiatus. Previously owned a ‘68 G. I recently test flew an Ovation and was surprised at the high CHTs throughout the flight. It was a summer morning flight in the SouthEast but the temps were approaching 500. 
What should I expect to see?

Ouch. You'll be burning through cylinders at an extreme rate! I live and fly in Las Vegas where it's usually super-hot. I rarely get CHT's above 390. Sometimes 400-410 in a climb until I drop the nose a bit. Also, I fly LOP at cruise. Something is wrong with either your fuel flow, baffling, and sensors. That is not right and should be setting off alarm bells if you're looking to buy that bird.

[midlifeflyer]

My experience is similar to @Niko182’s. In fact, my friend’s Ovation, which I fly, runs exceptionally cool. I wonder whether it’s a baffle issue?

[MJHarm]

Thanks everyone. We lowered the nose and reduced power to keep things reasonable. We’ll take a close look at the exhaust valves and baffling at pre buy.


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[Schllc]

Something is very wrong with that plane, and 500deg cht’s on a io-550 isn’t just high, it’s dangerous. 
I can’t believe the owner would fly it this way. 

[atpdave]

What fuel flow are you seeing with takeoff power setting? Assuming 280hp (full throttle, full rich, 2500 rpm at sea level), in my experience if it's less than about 23.5 GPH (per Mooney) it's set too low. CMI says 22.5 max but that's a little low, my guess is to make fuel consumption numbers look better (see Continental M-16 and Mooney MAN161).

If you can lean it out in cruise and get significantly lower CHTs with smooth operation then it's likely a fuel setup problem.

Previous owners of my plane were based in Glenwood Springs CO at 5916 MSL, and the logs indicate that they had been messing with the fuel flow, maybe to lean it out at idle. I'm based in Santa Fe NM at 6349 MSL and never saw max power CHTs above 400 around here, but in Texas that first summer they got up to 430-440 full rich, which got my immediate attention. I never saw numbers like you're seeing.

The first shop that did the fuel pressure/flow setup for me still set it low, but it was an improvement. When Maxwell did the 310 hp upgrade they got it right IMO and there's plenty of fuel now to keep CHTs comfortably lower during takeoff and climb-out from sea level.

In cruise I operate LOP and my CHTs are between 270 and 330 with cyl. 5 always hottest.

If you do buy the plane and find you need to adjust the fuel pressure/flow, I suggest you employ someone who is very familiar with the Continental/Mooney-specific fuel setup procedure.

[MJHarm]

20 hours ago, atpdave said:

What fuel flow are you seeing with takeoff power setting? Assuming 280hp (full throttle, full rich, 2500 rpm at sea level), in my experience if it's less than about 23.5 GPH (per Mooney) it's set too low. CMI says 22.5 max but that's a little low, my guess is to make fuel consumption numbers look better (see Continental M-16 and Mooney MAN161).

If you can lean it out in cruise and get significantly lower CHTs with smooth operation then it's likely a fuel setup problem.

Previous owners of my plane were based in Glenwood Springs CO at 5916 MSL, and the logs indicate that they had been messing with the fuel flow, maybe to lean it out at idle. I'm based in Santa Fe NM at 6349 MSL and never saw max power CHTs above 400 around here, but in Texas that first summer they got up to 430-440 full rich, which got my immediate attention. I never saw numbers like you're seeing.

The first shop that did the fuel pressure/flow setup for me still set it low, but it was an improvement. When Maxwell did the 310 hp upgrade they got it right IMO and there's plenty of fuel now to keep CHTs comfortably lower during takeoff and climb-out from sea level.

In cruise I operate LOP and my CHTs are between 270 and 330 with cyl. 5 always hottest.

If you do buy the plane and find you need to adjust the fuel pressure/flow, I suggest you employ someone who is very familiar with the Continental/Mooney-specific fuel setup procedure.

Thanks much, I didn’t note the fuel flows as I was too enamored with being back in a Mooney but I have a MSC rep doing the pre buy and will talk to him about the engine baffling and fuel flows as settings along with a thorough boresope inspection. 

[Niko182]

If you are doing a pre buy I would see if you can download the history on that jpi 700. I would not want to buy an engine that has touched 500 degrees or been close to that. I wouldn’t be surprised if it’s toasted and an overhaul is needed soon.

[NickG]

A couple of the things about BA to look for (other than maintenance history in logs, damage history etc). 1) Speed brakes inop??? That can be quite expensive. Find out why. 2) Also, check why" Factory O2 plumbing, tank has been removed". Is this something you want to install? Was the useful load with the O2 or without? If without, adding it back will likely drop your useful load into the 870# area.... 

[MJHarm]

5 hours ago, Niko182 said:

If you are doing a pre buy I would see if you can download the history on that jpi 700. I would not want to buy an engine that has touched 500 degrees or been close to that. I wouldn’t be surprised if it’s toasted and an overhaul is needed soon.

I was thinking along the same lines.  Thanks!

[MJHarm]

2 hours ago, NickG said:

A couple of the things about BA to look for (other than maintenance history in logs, damage history etc). 1) Speed brakes inop??? That can be quite expensive. Find out why. 2) Also, check why" Factory O2 plumbing, tank has been removed". Is this something you want to install? Was the useful load with the O2 or without? If without, adding it back will likely drop your useful load into the 870# area.... 

So both are reportably due to lack of use. He had the speed brakes repair only to have them fail again and then just left them inop. Same with the O2. His mission just didn’t require it and from my understanding once that tank goes “dry” it requires recertification(?).  The useful load is without the bottle. 870#? Oof! I luckily for me, 90% of my flying will be just the wife and me.

[NickG]

If you've got all of the plumbing still there for the O2 system I would get a new bottle (composite ones are lighter). You'll be losing alot of the functionality of the Ovation if you only fly below 12,500ft.

No, the useful load is, I would hope 930# as stated in the ad. I'm assuming this was the load with the bottle installed. It will be slightly better with no bottle. However, if the 930# was UL with the bottle REMOVED, then your useful load will be less by whatever the bottle weighs.

Speedbrakes are a must and you should get them repaired. However, not cheap to repair.

[Bolter]

1 hour ago, NickG said:

Speedbrakes are a must and you should get them repaired. However, not cheap to repair.

Not to pick a fight, but there is a split of opinions on this.  I personally do not consider speed brakes to be essential, and I would easily buy a plane without them, or if they were inop.  Other than occasional testing for function, I plan my approaches without using the brakes.  My J did not have them, so perhaps it is just drilled into me, despite the 20 KTAS extra cruise speed of the R. 

I do agree that maintaining the plane properly means fixing things you may not use (I just rebuilt mine at annual with Precise Flight, $2450 when one failed a function test at annual) so it is a warning to look for neglected maintenance items.  Maintenance is a commitment.  While there are different opinions on what is proper maintenance (I am well past TBO, and others overhaul at TBO automatically, for example) non-functioning items that are ignored are never proper maintenance.  Of course, in the age of hard to get parts, INOP something waiting for a fix, is common, and I would not judge harshly for that.

And completely my opinion about this plane, and being blunt and probably offending the seller, removing the O2 tank and leaving that system non-functioning rather than replacing it, INOP'ing the speed brakes because they became costly, are 2 examples of penny pinching.  While the plane may be a good platform without corrosion, I would approach cautiously for what other systems are held together with speed tape and zip ties and value it accordingly.  Little things can nickel and dime you, as well as keep you grounded instead of flying.  When I searched for a FIKI Ovation, I valued the detailed and proactive maintenance of my Ovation that were done before I got it, and it has operated flawlessly for over 3 years.   @Cruiser  And I think the buyer of my J should feel the same way.

[NickG]

2 hours ago, Bolter said:

Not to pick a fight, but there is a split of opinions on this.  I personally do not consider speed brakes to be essential, and I would easily buy a plane without them, or if they were inop.  Other than occasional testing for function, I plan my approaches without using the brakes.  My J did not have them, so perhaps it is just drilled into me, despite the 20 KTAS extra cruise speed of the R. 

I do agree that maintaining the plane properly means fixing things you may not use (I just rebuilt mine at annual with Precise Flight, $2450 when one failed a function test at annual) so it is a warning to look for neglected maintenance items.  Maintenance is a commitment.  While there are different opinions on what is proper maintenance (I am well past TBO, and others overhaul at TBO automatically, for example) non-functioning items that are ignored are never proper maintenance.  Of course, in the age of hard to get parts, INOP something waiting for a fix, is common, and I would not judge harshly for that.

And completely my opinion about this plane, and being blunt and probably offending the seller, removing the O2 tank and leaving that system non-functioning rather than replacing it, INOP'ing the speed brakes because they became costly, are 2 examples of penny pinching.  While the plane may be a good platform without corrosion, I would approach cautiously for what other systems are held together with speed tape and zip ties and value it accordingly.  Little things can nickel and dime you, as well as keep you grounded instead of flying.  When I searched for a FIKI Ovation, I valued the detailed and proactive maintenance of my Ovation that were done before I got it, and it has operated flawlessly for over 3 years.   @Cruiser  And I think the buyer of my J should feel the same way.

No fight to pick. And I 100% agree with your take. I'd be VERY careful looking at this bird's maintenance records. 

[NewMoon]

On 7/2/2025 at 4:11 PM, MJHarm said:

Thanks everyone. We lowered the nose and reduced power to keep things reasonable. We’ll take a close look at the exhaust valves and baffling at pre buy.


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Don't reduce power, that reduces fuel flow and adds to the problem

[MJHarm]

Thanks everyone for the advice and insights. I ordered a pre buy but based on the results, decided to pass on this Ovation. The search continues…