Any P Ponk fliers/owners?

[jsstevens]

Since this engine was installed, we have EGTs and CHTs recorded on all cylinders, plus a fuel flow monitor. The high CHT we are seeing is a change in this cylinder from the past 800 hours of operation. There is no change in fuel flow, and we have checked the induction system. There also isn't any apparent change in the baffling, so we we're reduced to assuming there could be a valve issue developing in this cylinder. Note this is a small change at this point - unrestricted climb CHT under similar OATs used to peak around 385F in this cylinder, now we have to reduce climb rate to 500 fpm to keep the temp below 400F, which is what we consider our "warning" temp. Folks flying with a single CHT gauge would likely have no clue such a problem was developing, but we tightly manage the maintenance of this plane. 400F is also a conservative temp to use as a warning level.

Curiosity side question: What is the mechanism for valve problems increasing CHT? I can understand a leaky exhaust valve causing a rise in EGT.

John

Edit: Change "amusing", thanks autocorrect, for "causing".

 

[Ted]

Could also be an ignition issue, worth looking into. But if you're seeing 385F in normal unrestricted climb, that's pretty good.

 

[Jeff Oslick]

Curiosity side question: What is the mechanism for valve problems increasing CHT? I can understand a leaky exhaust valve causing a rise in EGT.

A valve problem (e.g., sticking) can lead to excessive pressures during the combustion cycle, elevating CHT. The last borescope look we had a few weeks ago didn't reveal anything obvious. Changed the oil and ran for another 10 hours.

We have also checked the timing and put in new plugs, doesn't appear to be an ignition issue, unless it is a hidden issue with the spark plug lead.

Jeff

 

[Jeff Oslick]

But if you're seeing 385F in normal unrestricted climb, that's pretty good.

It's been a nearly-perfect engine until this issue. Only other issues we've had were a few minor oil leaks (which I learned about 10 years ago is the sign of a big-bore Conti that has actually been run...).

 

[jsstevens]

A valve problem (e.g., sticking) can lead to excessive pressures during the combustion cycle, elevating CHT. The last borescope look we had a few weeks ago didn't reveal anything obvious. Changed the oil and ran for another 10 hours.

We have also checked the timing and put in new plugs, doesn't appear to be an ignition issue, unless it is a hidden issue with the spark plug lead.

Jeff

Thanks. I read, I learn. Someday I might own one of these beasts and need to know this stuff.

John

 

[Henning]

Just so everyone doesn't think the Pponk is an infallible gift from the aviation gods, we are looking at pulling a couple jugs next week on ours. Possibly a valve issue in one cylinder (high CHT during climbs) and a ring issue in another (generating some metal flakes in the filter and elevated chromium and lead in our oil analysis). It is a mid-time big-bore Conti, and our use-hours fell off a bit the last couple years leading to some longer than desirable down times, so none of this is surprising to us.

Fortunately, with a 3-way partnership, the pain shouldn't be too bad.

Jeff

Out of curiosity, how rich do you run?

 

[Jeff Oslick]

Out of curiosity, how rich do you run?

I run ~125 ROP at >70% power. In cruise (<65%), I run at peak or if the engine is cooperating, a bit lean of there. One of the partners is more aggressive than I in the leaning category than me. I haven't flown with him enough recently to really know what if anything he is doing differently. That may or may not be a subject of discussion on further examination of the engine, but I have no reason to believe he is operating it too lean at too high a power setting. We started in this plane with a stock O-470, and in cruise run the same TAS as we used to, just with more hp on tap up front for climb.

I suspect our issues are more related to reduced hours on the engine in the past couple years more than anything else. A 2-3 week layover between flights hasn't been uncommon.

Jeff

 

[denverpilot]

It's been a nearly-perfect engine until this issue. Only other issues we've had were a few minor oil leaks (which I learned about 10 years ago is the sign of a big-bore Conti that has actually been run...).

ROFL!

 

[Dr. O]

Having owned Lanes and various Continental engines over the years this thread has been interesting.
The loudest Continental engine I had was an IO-520D in a super viking with the long 2 blade prop. It would shake the airport on takeoff. But it cruised like a scalded cat.
In a P-Ponk I would tend to prefer the 2 blade for the cruise efficiency over a 3 blade, even if the 2 blade gives up a bit of climb. I spend way more time in cruise than I do in climb.
The fastest stock Lane I had was a 56 model with the lower hp engine but the straight tail. It annoyed our local Chevy dealer with his brand new, slickly styled, swept tail Lane that I would slide right past him by a few knots. (I was lighter also)

I always said, and still do, that if I had to pick just one airplane for my entire life it would be the Skylane.

 

[Ted]

It's been a nearly-perfect engine until this issue. Only other issues we've had were a few minor oil leaks (which I learned about 10 years ago is the sign of a big-bore Conti that has actually been run...).

That isn't necessarily true, although leaks are common. But for reference, the 2100 SMOH factory remans on the 310 didn't leak a drop of oil when we pulled them for overhaul.

It really does depend on who does the work.

 

[Henning]

I run ~125 ROP at >70% power. In cruise (<65%), I run at peak or if the engine is cooperating, a bit lean of there. One of the partners is more aggressive than I in the leaning category than me. I haven't flown with him enough recently to really know what if anything he is doing differently. That may or may not be a subject of discussion on further examination of the engine, but I have no reason to believe he is operating it too lean at too high a power setting. We started in this plane with a stock O-470, and in cruise run the same TAS as we used to, just with more hp on tap up front for climb.

I suspect our issues are more related to reduced hours on the engine in the past couple years more than anything else. A 2-3 week layover between flights hasn't been uncommon.

Jeff

75°-125° ROP is the absolute worst temp range to run at. Try 150° and see what happens.

 

[Henning]

A valve problem (e.g., sticking) can lead to excessive pressures during the combustion cycle, elevating CHT. The last borescope look we had a few weeks ago didn't reveal anything obvious. Changed the oil and ran for another 10 hours.

We have also checked the timing and put in new plugs, doesn't appear to be an ignition issue, unless it is a hidden issue with the spark plug lead.

Jeff

How? Valves stick open, not shut. If a valve sticks shut, you will immediately break something in the valve train, usually bending the push rod. Once it happens, you lose that cylinder until repaired. Sticking and burnt valves cause high EGT, not CHT.

 

[Ted]

75°-125° ROP is the absolute worst temp range to run at. Try 150° and see what happens.

Most people figure it's about 25-80 ROP is the worst. That's when CHTs and ICPs peak.

 

[txflyer]

Tagging in because we put an MT prop on our C-180G in anticipation of a PPonk or 0-550 upgrade when it's time. The mating of the two blade MT to the 180 frame I haven't regretted. It's quiet, it pulls hard, and it will handle an 0-470-50 or 0-550 upgrade with superior cruise over most three blades. It ain't as sexy, but hey, it's a skywagon. Plus, it shaved nine pounds off the very front C.G. station. A perfect match for our nose heavy ground looper.

It's hard to decide. I've read Grandpa's shtick that the stock 0-470's in the Cessna 18x series have their virtues as well as the intoxicating lust for more power. They burn less, you can keep your auto-gas STC, they run cooler, less weight, and are a cheaper and trusted bullet-proof design that's been tested by time. And they're not THAT much slower in the grand scheme of things. If it ain't broke .. yada yada ...

But I still want more power and speed on tap. Who doesn't?

 

[Jeff Oslick]

How? Valves stick open, not shut. If a valve sticks shut, you will immediately break something in the valve train, usually bending the push rod. Once it happens, you lose that cylinder until repaired. Sticking and burnt valves cause high EGT, not CHT.

We're not seeing a huge increase in CHT here, just about 20F or so at full power. Anything that messes with the F/A ratio can cause a higher CHT. We're (obviously) not certain of the cause, which is why that cylinder is coming off.

 

[Jeff Oslick]

75°-125° ROP is the absolute worst temp range to run at. Try 150° and see what happens.

125 is as lean as i would run it >75% power. It's not really relevant though, our plane spends very little time over 65% power unless in a climb (where we run quite rich).

 

[Henning]

We're not seeing a huge increase in CHT here, just about 20F or so at full power. Anything that messes with the F/A ratio can cause a higher CHT. We're (obviously) not certain of the cause, which is why that cylinder is coming off.

Have you checked out the spark plugs?

 

[Ted]

Tagging in because we put an MT prop on our C-180G in anticipation of a PPonk or 0-550 upgrade when it's time. The mating of the two blade MT to the 180 frame I haven't regretted. It's quiet, it pulls hard, and it will handle an 0-470-50 or 0-550 upgrade with superior cruise over most three blades. It ain't as sexy, but hey, it's a skywagon. Plus, it shaved nine pounds off the very front C.G. station. A perfect match for our nose heavy ground looper.

It's hard to decide. I've read Grandpa's shtick that the stock 0-470's in the Cessna 18x series have their virtues as well as the intoxicating lust for more power. They burn less, you can keep your auto-gas STC, they run cooler, less weight, and are a cheaper and trusted bullet-proof design that's been tested by time. And they're not THAT much slower in the grand scheme of things. If it ain't broke .. yada yada ...

But I still want more power and speed on tap. Who doesn't?

People make that same sort of argument relative to the 310s and 470s vs. 520/550s. I think for the most part they're right, but the real benefit is for takeoff/climb if you tend to fly hot/heavy or short fields. Twins get the added benefit of better OEI performance. So I think it's a no-brainer. A lot of me wishes we'd done the 550 upgrade in the 310 when we did the engines, but the cost delta of that vs. the 520s was going to be too much to be reasonable, and since the 520s are already 300 HP (just at 2850 RPM instead of 2700), the benefits of the 550s would've been much lower than from the 260 HP 470s to either 520s or 550s.

 

[Skip Miller]

Hi gang.

Hi back! and welcome!

When is an aircraft engine typically considered to be "broken in"?

Generally "broken in" means your oil consumption has stabilized. It will be higher immediately after new/overhaul, and should subside to a stable level after five or ten hours if you followed proper break-in procedure.

How has your oil consumption been?

-Skip

 

[Henning]

People make that same sort of argument relative to the 310s and 470s vs. 520/550s. I think for the most part they're right, but the real benefit is for takeoff/climb if you tend to fly hot/heavy or short fields. Twins get the added benefit of better OEI performance. So I think it's a no-brainer. A lot of me wishes we'd done the 550 upgrade in the 310 when we did the engines, but the cost delta of that vs. the 520s was going to be too much to be reasonable, and since the 520s are already 300 HP (just at 2850 RPM instead of 2700), the benefits of the 550s would've been much lower than from the 260 HP 470s to either 520s or 550s.

Yeah, I don't miss the 80hp at the weights I fly at, by 700' I am already 2500rpm and going for 15°LOP climbing nicely enough. Until I can replace with Diesels, I'll keep these 470s running. She just passed annual with no hassles and got a few known squawks worked out. $5500 total. Might have him handle a couple more little projects.

 

[Jeff Oslick]

Have you checked out the spark plugs?

Read above, they were replaced, and the timing checked.

 

[txflyer]

People make that same sort of argument relative to the 310s and 470s vs. 520/550s. I think for the most part they're right, but the real benefit is for takeoff/climb if you tend to fly hot/heavy or short fields. Twins get the added benefit of better OEI performance. So I think it's a no-brainer. A lot of me wishes we'd done the 550 upgrade in the 310 when we did the engines, but the cost delta of that vs. the 520s was going to be too much to be reasonable, and since the 520s are already 300 HP (just at 2850 RPM instead of 2700), the benefits of the 550s would've been much lower than from the 260 HP 470s to either 520s or 550s.

The 550 upgrade is an involved and much more complicated install compared to the Pponk upgrade from what I read.

Fuel pumps must be installed for the 550 with return lines. The good ol' Cessna gravity feed system that is so simple and reliable is gone.

And the cost is 100% different. The 550's can cost upwards of $60,000.00 to convert, while the PPonk can be had all day long for half that. I'm preaching to the choir, but you better either have oil wells or have some serious flying to do to warrant a $60K engine upgrade on a $100K bird.

 

[Henning]

Read above, they were replaced, and the timing checked.

Injector plugged?

 

[Jeff Oslick]

Injector plugged?

Carbed. Induction lines already checked. Only other thing I can imagine is a compromised ignition wire. Our current harness has around 7 years and 1,100 hours on it, so that is certainly possible.

Jeff

 

[Henning]

Carbed. Induction lines already checked. Only other thing I can imagine is a compromised ignition wire. Our current harness has around 7 years and 1,100 hours on it, so that is certainly possible.

Jeff

Yep, a bad wire can cause this. I would do a bore scope inspection on the cyl before pulling it. If there is something wrong with the jug that is starting to make it run hotter, you'll see evidence of it.

Another thing to check is valve/ cam lift. If the exhaust lobe is giving up or pushrod worn/bent, that will bring up the CHT in that cyl.

 

[Jeff Oslick]

Yep, a bad wire can cause this. I would do a bore scope inspection on the cyl before pulling it. If there is something wrong with the jug that is starting to make it run hotter, you'll see evidence of it.

Another thing to check is valve/ cam lift. If the exhaust lobe is giving up or pushrod worn/bent, that will bring up the CHT in that cyl.

Was borescoped a few weeks ago. Nothing obvious, but the borescope setup used was less than ideal. Will be done again before pulling. Again, this is a fairly subtle issue that anyone without closely monitored CHTs would likely never see until the problem got ugly.

 

[FlyingBob]

Hi back! and welcome!



Generally "broken in" means your oil consumption has stabilized. It will be higher immediately after new/overhaul, and should subside to a stable level after five or ten hours if you followed proper break-in procedure.

How has your oil consumption been?

-Skip

I haven't flown more than 20hrs yet since owning it, so no oil consumption yet.

 

[FlyingBob]

Yeah, I don't miss the 80hp at the weights I fly at, by 700' I am already 2500rpm and going for 15°LOP climbing nicely enough. Until I can replace with Diesels, I'll keep these 470s running. She just passed annual with no hassles and got a few known squawks worked out. $5500 total. Might have him handle a couple more little projects.

$5500 for an annual? Holy, what did your A&P do?

 

[Ted]

The 550 upgrade is an involved and much more complicated install compared to the Pponk upgrade from what I read.

Fuel pumps must be installed for the 550 with return lines. The good ol' Cessna gravity feed system that is so simple and reliable is gone.

And the cost is 100% different. The 550's can cost upwards of $60,000.00 to convert, while the PPonk can be had all day long for half that. I'm preaching to the choir, but you better either have oil wells or have some serious flying to do to warrant a $60K engine upgrade on a $100K bird.

Agreed, for that price difference the PPonk makes far more sense than the 550 conversion. I'm not familiar with the different options on that airframe since it's not one I deal with much.

On the 310, current prices for the 520 and 550 conversions are the same. The difference is that the 520 conversion came out first, and most converted 310s have 520s. Rs are a different story, but they came with 520s from the factory.

The issue is that, even though there's really nothing different besides the engines on the 520/550 conversion, they won't give you a "returning customer" discount, so basically to go from 520s to 550s you're shelling out as much as from 470s to 550s.

And then that gets into that $120k to put into an $80k bird deal...

 

[txflyer]

Agreed, for that price difference the PPonk makes far more sense than the 550 conversion. I'm not familiar with the different options on that airframe since it's not one I deal with much.

On the 310, current prices for the 520 and 550 conversions are the same. The difference is that the 520 conversion came out first, and most converted 310s have 520s. Rs are a different story, but they came with 520s from the factory.

The issue is that, even though there's really nothing different besides the engines on the 520/550 conversion, they won't give you a "returning customer" discount, so basically to go from 520s to 550s you're shelling out as much as from 470s to 550s.

And then that gets into that $120k to put into an $80k bird deal...

I know on the 18x frames, the 550 upgrade I think I read requires a new beefier engine frame, mounts, and some cowl work. Along with all the fuel line re-working. So, it's not near as plug and play as the 0-470-50 upgrade.

And then of coarse every 550 must have GAMIjectors and an engine analyzer so you can go LOP to wring every drop of go juice out of that chunk of gold you just installed up front. As if to say, " hey! look! I'm saving money!

$30,000.00 will buy a lot of Avgas. That's the going price of an 0-550 upgrade over a Ponk on a 180 today.

 

[Stewartb]

Wow, lots of interesting comments. I've had a PPonk engine and C401-86" 3 blade prop for about 13 years on my 180J. Absolutely the best mod I've ever done to an airplane. A few thoughts.

The 470 case's cylinder decks must be machined to fit 520 cylinders. Most of us opt for a 7th stud mod at the same time. R and S model cranks won't work but other 470 cranks and all 520 cranks will. The 470 and 520 cranks have a different oil transfer so a crankcase would require adaptation to use the different crank. I have a 520 crank in a phase III 470 case. Works great.

High CHT is almost always related to fuel flow. This conversion is notorious for running too lean. PPonk does their proprietary carb mods and if you live in the north or anyplace where temps will get cool, you'll need to increase fuel flow from what Steve does. Cowl lovers help with temps, too.

Re: the three blade being slow? Not in my time running one. I'd cry like a baby if I had to go back to a 2 blade. With my 180 on 850s and a stock 8" tailwheel my break-in speeds were in the 180s mph. 13 years later with 29" Bushwheels and a bush tailwheel I cruise at 150mph easily at <1500' MSL. The C401 is a great prop. When this one wears out I'll buy another. Actually, when my current setup wears out I'll do an AirPlains conversion and install a LyCon IO-520D with my C401. More power, better temperature distributions, and better fuel economy. If you're going to New York don't get off in Cincinnati.