Time for the Cylinder Farey to Visit

[aviatoreb]

Continental cylinders lately often last only 900 hours, especially on factory engines. They don't machine the valves concentric with the seat and guide, and they eventually start to burn and fail. it doesnt matter of you run ROP or LOP, etc.

 

Hmmmm.... maybe you are right.  And I have certainly read this widely.  

 

After a full day's work to remove the exaust which covers the cylinders (rockets are tight) my AP has the 3 cylinders ready to ship.  I have been second guessing myself all day today though.  Second guessing my decision not to just go ahead and do the full top.  I already gave my reasoning above why not to do the full top based on AP's advice and also cylinder shops advice "if it ain't broke then don't fix it", and that seems reasonable.  But if those other 3 cylinders are doomed to go sometime in the next 100 or 200hrs anyway, then a full top now (at 985hrs) should see me through to TBO theoretically and save me the trouble of going through removing the exhaust and break-in and so forth.

 

I am flip flopping on this decision like a dozen times today.  Even though I was firm on the decision to just do the 3 cylinders as of two days ago.

 

>That's sad but on the other hand, they are not $2800 a pop like they are on the Bravo, so as they say, you can pay now, or you can pay later. Mine looked brand new at 1100 hours during overhaul and the previous owner always hauled ass at 32/2400. Could have kept them as is, but I elected to redo them at $1200 a pop with all new running gear.

 

It is sad.

 

>I still think the Lycoming with wet heads is a superior high altitude engine to the Continental.

 

How/in what way?

[BobAustin]

I have a MIssile (IO 550) not a Rocket but...About a couple of years ago at about 900 hrs I had a top overhaul at Mtn View Aeromotive, Alamosa CO.  Was throwing oil out at 2 qt per 4 hour flight.

 

Ron Ecord the owner sugested overhauling the first run cylinders.  Had to bore oversize, new pistons from Continental...etc.

 

Bottom line It runs great, burns about 1 qt every 25 hrs or so and will run 185K at full power vs 180 before.  Could not be happier.

 

Cost as I remember was under 6K.  No turbo or exaust plumbing like the Rocket.  Rod flew the first 2-3 hrs for breakin.

 

His overhauled cylinders are clearly better than those turned out by Continental.

 

Bob

 

85 Missile N211ZN

[carusoam]

EB,

Sounds more like an economics decision?

3 now and 3 later vs. 6 at once....

Cost of money, if you needed to borrow for the extra cylinders.

Two break-in periods vs. one.

Two times in the shop vs. one.

Imbalance between OH'd cylinders and old cylinders. (would this show on the EGTs and CHTs?)

I would seriously consider doing it all at once, there doesn't seem to be a significant economic reason to spread it out, unless cash flow is that critical.

One break-in period, one QC process, one tear down and rebuild, etc...

Some consideration for having the cylinders make it to engine TBO...is the engine at the theoretical halfway point already? (fuzzy logic...)

Anyone care to comment on my thought process here? In case I missed something obvious or not...

Best regards,

-a-

[aviatoreb]

EB,

Sounds more like an economics decision?

3 now and 3 later vs. 6 at once....

Cost of money, if you needed to borrow for the extra cylinders.

Two break-in periods vs. one.

Two times in the shop vs. one.

Imbalance between OH'd cylinders and old cylinders. (would this show on the EGTs and CHTs?)

I would seriously consider doing it all at once, there doesn't seem to be a significant economic reason to spread it out, unless cash flow is that critical.

One break-in period, one QC process, one tear down and rebuild, etc...

Some consideration for having the cylinders make it to engine TBO...is the engine at the theoretical halfway point already? (fuzzy logic...)

Anyone care to comment on my thought process here? In case I missed something obvious or not...

Best regards,

-a-

 

Thanks -a-,

 

You hit my logic spot on.  No the money is not the problem counter why to just not do it all now.  There is a principle that weighs on my that runs the counter argument not to do them all now. The principle is that sometimes unnecessary work can actually be a bad thing and can lead in principle terms to maintenance induced problems - I think this is what the cylinder shop must have been saying in some form when they said, "if it ain't broke, then don't fix it."  So their advice to not do the full top weighs on my too.

 

But from everything I have been reading all weekend, it makes it seem unlikely that those other 3 cylinders will make it to TBO and if that is the case.....seems like I should just do it now.  

 

So anyone, I would also love to hear further comment on the above logic.

[Awful_Charlie]

I think it just comes down to your attitude to unscheduled downtime and whether the A&P is based at your home field, rather than the increased risk of something going wrong after maintenance - you are already into that boat anyway by changing 3 jugs with all the work that entails, and adding the remaining 3 would be a lot less than doubling the risk on this occasion, but doing 3 pots later is going to be the same risk all over again at another time.

 

If it were me and I could afford it, I'd do all of them, maybe holding the serviceable jugs back for emergency spares in another 800+ hours!

[carusoam]

Maintaining the extras as spares sounds pretty good too...

-a-

[BigTex]

Before pulling the trigger on swapping out multiple jugs at the same time, I'd strongly suggest you watch Mike Busch's All About Cylinders. He goes into a lot of detail on why it's NEVER a good idea to do multiple cylinders at the same time unless you have too. If after watching this webinar and you still want to do multiple cylinders, at least you're going in knowing you're risks.

[aviatoreb]

Before pulling the trigger on swapping out multiple jugs at the same time, I'd strongly suggest you watch Mike Busch's All About Cylinders. He goes into a lot of detail on why it's NEVER a good idea to do multiple cylinders at the same time unless you have too. If after watching this webinar and you still want to do multiple cylinders, at least you're going in knowing you're risks.

 

Thanks - I will do that later this morning.  Maybe he will have just the information to settle my indecision on this one.

[KSMooniac]

I generally agree with Busch's philosophy and recommendations as well.  

 

Your case is tough to call... it does make sense on one level to re-baseline all of them "while yer in there" but that must be balanced against the risk of maintenance induced failures.  If you subscribe to the theory that Continental can't get their valves installed correctly at the factory, then you have a legitimate concern of the other 3 needing attention at some point in the future.  To counter that, you could go ahead and do all 6 and make sure the shop has a great process to get those valves installed perfectly and you'll likely have a better lasting cylinder than what you started with...

[aviatoreb]

I generally agree with Busch's philosophy and recommendations as well.  

 

Your case is tough to call... it does make sense on one level to re-baseline all of them "while yer in there" but that must be balanced against the risk of maintenance induced failures.  If you subscribe to the theory that Continental can't get their valves installed correctly at the factory, then you have a legitimate concern of the other 3 needing attention at some point in the future.  To counter that, you could go ahead and do all 6 and make sure the shop has a great process to get those valves installed perfectly and you'll likely have a better lasting cylinder than what you started with...

 

Well summarized Scott. I am really suffering over this decision.  I am leaning to doing just the 3 cylinders right now but I keep changing my mind.  The die will be cast tomorrow.  I bet I do just the 3.  It would be nice to have all 6 done and clean and done to TBO so I would say, but I agree with the Busch philosophy and the principle of don't fix it if it ain't broke.  Ughh.....

[carusoam]

What is the chance of the remaining three going to TBO?

I'm a little out on the Busch philosophy, but it seems like there are two choices....

(1) Fix three now and the other three in a year or two.

(2) Fix all six now and plan on going to TBO from here.

Or is it common to have randomness thrown in by the OEM cylinder producer?

Modern technology has improved the manufacturing process to a level that even the back woods of a foreign country can make parts consistently. I have seen rows of machinists, turned into a few CNC machines...

If I just bought six new NA cylinders from Continental, should I be concerned about randomness? I find this hard to believe and harder to accept. They have a printed break in procedure that can be followed. Having a JPI, or equivalent should keep the pilot apprised.

In the 90’s, this was the norm. In the post Y2K era, are we still thinking no two cylinder assemblies are the same.

Or is Continental still in the dark ages?

Best regards,

-a-

[KSMooniac]

There is strong anecdotal evidence over on Beechtalk (lots of Continental operators there!) that the factory STILL hasn't fixed their production problem related to fitting the valves.  Somewhere along the line they "cost-savingsed" the production process and dropped some steps, and the result has been non-concentric valve-seat fit, and that screws up the heat dissipation that is supposed to be transferred through the valve, into the seat, and out through the head.  Many of the savvy shops will take brand new cylinders and re-do the valve fit just to make sure they are correct, which is silly, but that is what I've read over and over.  It costs a bit more up front, but avoids the mid-term work being discussed in this thread... 

 

And yes, it should be a very simple thing to get right these days at a factory, but the American world is run by bean counters now, not engineers, machinists, or craftsmen.

[aviatoreb]

And the post script to the cylinder farey story.

 

I eventually decided to just do the whole top.  A rocket is so tight that it takes such a great deal of time to remove exhaust and stuff to get at the cylinders - and I decided I have such low confidence in the TCM factory cylinders possibility to make TBO even though they are showing good health at 985 hours - I decided just to replace all 6 cylinders with ECI Titan steel.

 

So here she is - ready to fly!  I have flown off 5 hours already.  Wow she sounds great and flew great.

 

I was surprised but they broke in almost instantly.  Like in 10 min the sound changed from roar to purr/roar and temps dropped.  But surprising temps were never high.  I never topped 360 on any CHT during the entire break in flight and as I varied settings in many combinations of 30'' to 35'' and 2300 to 2700 - I burned a lot of fuel in ~2hours making laps around the airport at 6k and 10 mi out at 170 to 200kts depending on setting and wind direction.  Eventually after about a half hour I stopped with extreme rich settings and moved to POH recommended ROP settings and I closed cowl flaps and she stayed nice and cool anyway.  It helped that it was 35-40F on the ground at SLK where I was having fun.  The second flight of the day I burned very little to no oil - it is hard to see with that clear mineral stuff for sure exactly how much.  Third flight of the day I am sure I burned none.  I am sure she is at least 5kts faster at any given setting.  I'm in rocket love all over again.  Oh - great news - we of course saw inside the cam and lowers and everything is clean as a whistle!  Yay!

[KSMooniac]

Yippee!  Probably a wise decision to do all 6 now and enjoy many more years of service without that nagging feeling of something about to happen.

[aviatoreb]

Yippee!  Probably a wise decision to do all 6 now and enjoy many more years of service without that nagging feeling of something about to happen.

 

Thanks Scott.  You said it just right.  All wisdom and struggle to make the ideal decision aside - it was that nagging feeling that I didn't want to deal with.

 

It took longer than I expected - there was a tiny trim control piece that came up in annual that we thought would be a quick and easy fix but the part turned out to be a bitch to find - and we didn't start looking for like 3 or 4 weeks since the top seemed to be pre-occupying.  But today was a glorious day in every way.  A fresh smelling and new looking plane and clear blue skies and crisp air to help.  I am positively giddy after 5hours of flying first in circles and then rip-roaren all around the state and area.

[Awful_Charlie]

Yay!  Glad it worked out - now I can see I need to get myself over your way sometime

[aviatoreb]

Yay!  Glad it worked out - now I can see I need to get myself over your way sometime

 

I would love that Charlie.

 

Or should I call you Awful?

[aviatoreb]

I think I must be an engine geek.  I like looking at sexy engines.

[carusoam]

Need to increase the brightness for better viewing of the turbo???

-a-

[carusoam]

Hey, what happened to my icon???

-a-

[bd32322]

Thanks Scott.  You said it just right.  All wisdom and struggle to make the ideal decision aside - it was that nagging feeling that I didn't want to deal with.

 

It took longer than I expected - there was a tiny trim control piece that came up in annual that we thought would be a quick and easy fix but the part turned out to be a bitch to find - and we didn't start looking for like 3 or 4 weeks since the top seemed to be pre-occupying.  But today was a glorious day in every way.  A fresh smelling and new looking plane and clear blue skies and crisp air to help.  I am positively giddy after 5hours of flying first in circles and then rip-roaren all around the state and area.

Congrats! Hoping to get a similar feeling once my IO360 comes back from zephyr

[David Mazer]

So glad everything has worked out well.  Fly safe and happy!

[jetdriven]

Here's something to look at. I dont have any strange fetishes, but I sure love me a huge motor.

 

Brand new Lycoming IO-360 (weak)

 

IO-550 in a Missile (badass)

 

TNIO-550-G in an Acclaim (232 knots worth)

 

[aviatoreb]

Here's something to look at. I dont have any strange fetishes, but I sure love me a huge motor.

 

Brand new Lycoming IO-360 (weak)

 

IO-550 in a Missile (badass)

 

TNIO-550-G in an Acclaim (232 knots worth)

IMG_2467.jpgIMG_1598.jpgIMG_7996.jpg

 

Topless.

 

Yup - I think I do have an engine fetish.  Those are beautiful each in their own way.

[jetdriven]

Show us yours.

 

There's an old saying "There is no replacement for displacement."

 

And another "Injection is nice but I'd rather be blown"