TIO540-AJ1A Lycoming Cylinder Advise
- Thread starter Alexb2000
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UngaWunga
Pattern Altitude
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UngaWunga
Aren't guides reamed to the size of the valves? If so, it shouldn't be an issue. Do these guides have valve guide seals? Sorry, all I know is car and motorcycle engines.
Anyways, good call on picking up your parts. Sounded like his business model wasn't that successful.
If you're concerned about the valves that are 0.0001" out of spec, replace just those.
What's the range of measurements you're seeing in the valves? I'd think the guides would wear faster than the valves. Wonder if the difference in the valve stem thickness is due to manufacturing, not wear.
.0001 is 40 times finer then a human hair...
I have been a machinist most of my life and I bet maybe just a handful of people could actually measure that close consistantly....
Valve stems are ground on a centerless grinder... They are perfectly straight. They will wear to a slight taper because of the rocker arms forcing them sideways during the stroke.....
Roller rockers help with that issue alot.......
Too bad aviation is stuck in the 1940's...
....
.0001 is 40 times finer then a human hair...
I have been a machinist most of my life and I bet maybe just a handful of people could actually measure that close consistantly....
Valve stems are ground on a centerless grinder... They are perfectly straight. They will wear to a slight taper because of the rocker arms forcing them sideways during the stroke.....
Roller rockers help with that issue alot.......
Too bad aviation is stuck in the 1940's...
High accuracy laser measuring devices are getting pretty affordable.
Henning;1640018[B said:
For a production shop, it could be a safe investment.. For a FBO /small rebuilder... not so much..
Ted
The pilot formerly known as Twin Engine Ted
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iFlyNothing
Buy an experimental and be done with this sort of ridiculous ****. Just my opinion
Agreed. Alex, you'd be a great candidate for a Lancair IV-P.
Alexb2000
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Yes, dodged that one.
That's the rumor
Not that I am aware of. What I was saying is that if you are holding one end of the valve in your hand the body heat will expand that section a tenth or two.
Buy an experimental and be done with this sort of ridiculous ****. Just my opinion
Why are they all so small? I need a bigger experimental.
.0001 is 40 times finer then a human hair...
I have been a machinist most of my life and I bet maybe just a handful of people could actually measure that close consistantly....
Valve stems are ground on a centerless grinder... They are perfectly straight. They will wear to a slight taper because of the rocker arms forcing them sideways during the stroke.....
Roller rockers help with that issue alot.......
Too bad aviation is stuck in the 1940's...
I measured each place literally 5 times. I "calibrated" my micrometer hand several times before taking any measurments using a .500 gauge block so I could get the feel hitting that dimension. I feel good about the measurements considering the application.
I have 100% faith in your measurements..... I have ZERO faith in the chicken coop,( Faa certified ) shops numbers...
In an earlier life I was a auto /industrial machinist.. From boring blocks to grinding cranks, and everything in between.... My specialty was Align boring blocks.. I probably have done 4000- 5000 of them... Most were BIG diesels... Cats, Cummins, John Deere, Detroit Diesels, etc etc..... The high dollar ones were V-12 /V-16 Cats.. Main bearing housing bore size was 6+ inches... Blocks weighed tons... And bigger then a pick up truck... My tolerance was =+ /- .0002".... Screw it up and I owned a 50 grand piece of cast iron.... I am proud to say... I NEVER killed even one ....
And your comment about the " calibrated micrometer hand" clearly tells me you know your siht...
Alexb2000
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The guides are reamed, no seals, the issue is the stem wear on the valve (thinner in the middle).
Read the first post about the cost of an individual valve, just exhaust valves and guides are ~$10K at super wholesale pricing.
You're right the guides to wear much faster, but as Ben said the valves are center less ground and perfectly consistent when they go into service. The guides cannot compensate for uneven wear on the stem, which is the root of the problem.
bnt83
Final Approach
Is there a turbine conversion available for these airplanes? Might as well be turbine if parts are priced similarly.
Alexb2000
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Really bad situation. I believe I've made my point with the shop and they feel bad about it.
Only $800K for the conversion. :wink2: My friend with a Jetprop said that if he ever has an annual under $30K it's party time. I don't know if the grass is always greener.
Several, IIRC there is even a twin Soloy conversion for the 206.
bnt83
Final Approach
I've worked a single Soloy before but it's wast in this new of 206
Alexb2000
En-Route
Only the government could afford to do it though.
http://www.soloy.com/files/Products/Documents/2014 - 206H w B17F Price Sheet 01162014.pdf
Ted
The pilot formerly known as Twin Engine Ted
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iFlyNothing
That's part of why I don't have an experimental. I have a future project of rebuilding a Twin Cessna as experimental, or making a ground-up build that includes the nice features that I'd like, such as a pilot door...
Alexb2000
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Here something close, cheaper than building it.
http://www.controller.com/listingsd...09-AIRPLANE-FACTORY-SPEEDSTAR-850/1313225.htm
If the certificate wasn't so restrictive, it would be really interesting.
Dr. O
Pattern Altitude
Alex, I have been around engines my whole life.
And I won't bore you with the details of 16 years spent around engine plants
Let me make one suggestion
Send the cylinders and parts to Charlie for inspection and assembly
And I won't bore you with the details of 16 years spent around engine plants
Let me make one suggestion
Send the cylinders and parts to Charlie for inspection and assembly
Ted
The pilot formerly known as Twin Engine Ted
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iFlyNothing
This gets into the need for an "owner experimental" category.
What are the restrictions on the certificate? There's a Twin Commander been flying Ex R&D with Orenda engines for decades now with no practical restrictions outside commercial ops.
Except as proposed it won't fall within the weight.
Experimental R&D allows you plenty of time and latitude to gather STC data.Alexb2000
En-Route
What are the restrictions on the certificate? There's a Twin Commander been flying Ex R&D with Orenda engines for decades now with no practical restrictions outside commercial ops.
Which of these categories would work when you land in front of the FAA and your family piles out ready for a beach trip?
https://www.faa.gov/aircraft/air_cert/airworthiness_certification/sp_awcert/experiment/
Exp R&D seems to work pretty well in practice.
Alexb2000
En-Route
So here's the update, still AOG.
I talked at length with the shop, they wanted to send them to their primary cylinder shop Gibson in OK along with their normal shipment. So I let them go up there to let the shop have a chance to make things better. Gibson has a go no go gauge for the valve stems made to a Lycoming spec that they use. Anyway, the good news is they all passed and the spec was more forgiving than we were originally told. Seems crazy after another shop said all failed, but I guess that's the way it goes in this game.
I do need a couple of guides, OK, no biggie I expected them to be done this week. Nope, apparently their heat bench went down and won't be up until the end of next week. So…. looks like two more weeks.
i could chew nails at this point, but what good would it do? I can say conclusively that in any of my business' if I impacted a customer like this they would NEVER do business with me again.
I'm still blown away that I was looking at a $13-14K dollar cylinder bill after Lycomings $6500 credit, plus about $4K for this years annual or $18K total. Now I should be out the door under $5K with basically a new top end. This kind of thing should never happen and I'm real determined to make some changes so it doesn't going forward.
I talked at length with the shop, they wanted to send them to their primary cylinder shop Gibson in OK along with their normal shipment. So I let them go up there to let the shop have a chance to make things better. Gibson has a go no go gauge for the valve stems made to a Lycoming spec that they use. Anyway, the good news is they all passed and the spec was more forgiving than we were originally told. Seems crazy after another shop said all failed, but I guess that's the way it goes in this game.
I do need a couple of guides, OK, no biggie I expected them to be done this week. Nope, apparently their heat bench went down and won't be up until the end of next week. So…. looks like two more weeks.
i could chew nails at this point, but what good would it do? I can say conclusively that in any of my business' if I impacted a customer like this they would NEVER do business with me again.
I'm still blown away that I was looking at a $13-14K dollar cylinder bill after Lycomings $6500 credit, plus about $4K for this years annual or $18K total. Now I should be out the door under $5K with basically a new top end. This kind of thing should never happen and I'm real determined to make some changes so it doesn't going forward.
sixpacker
Pre-takeoff checklist
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Sixpacker
Ouch! I remember having some expensive cylinder work at the engine 500-600 hour mark on my 206 with the same engine TIO540-AJ1A but maybe a third of what you're paying now and certainly not this long delay you've had. So what kind of changes are you going to make? Changing the shop for one I'm sure...
Alexb2000
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What cylinder work did you have done? Mine were running perfect, this is just a result of an SB for the intake valves. Otherwise I have no reason to believe they wouldn't have gone to TBO.
Hard to say, what I will do just yet. Remote shops mean getting there and back, less chance to go there physically, less chance to lay my eyes on a problem. I've also noticed if you really dig into a lot of mechanics shops they are not really setup to deal with certain features of TAA's, so I assume they skip the specific test called for. Amsafe testing, standby battery load testing, etc. I asked one if they could do my annual, they said, "no problem". I asked about the mentioned testing, blank stare, not good.
bnt83
Final Approach
Another consideration is opening a can of worms before the holidays. I've never had good luck getting parts in a timely manner from November to January.
YMMV
Alexb2000
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I agree, I took my aircraft in in Oct. thinking it would be out by Nov. 1 and I'd be using it over the holidays.
sixpacker
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Sixpacker
I had issues with two of the cylinders where the left exhaust manifold attaches. When I bought the plane it had been sitting for a while and I suspect that there was some corrosion that had been repaired. Perhaps a couple of bolts had been broken and then repaired. There was evidence a couple had been drilled and retapped. Anyway the bolts started working themselves loose. I had them retightened and the prop balanced and had the rest of the exhaust system checked. All the exhaust gaskets were changed. I don't remember the exact details other than the exhaust system has parts that are basically loosely fitting (sliding sections) and expand and close when getting hot?
After getting it back I didn't trust the situation and my preflight for the first few flights was to pull the cowl off and inspect it all carefully myself and sure enough saw evidence of the the bolts backing out again (telltale signs of discoloration and the gasket showing signs of waving). Called the A&P over and he agreed that we had an issue. So we then decided to pull both cylinders and ship to a shop in OK and finally the repair was made. After this I had no more problems.
Alexb2000
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OK, so not really a cylinder problem in the normal sense, more of a poorly done repair. I bet that drill out and retapping wasn't in the logs.
sixpacker
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Sixpacker
OK, so not really a cylinder problem in the normal sense, more of a poorly done repair. I bet that drill out and retapping wasn't in the logs.
Yes exactly, and the kind of thing you cannot find easily during the prebuy. Funny how it wasn't in the logs
Alexb2000
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The saga continues. We got the cylinders back from Gibson in OK. IMO they look really good, you might consider them if you need some cylinder work. So the reassembly was started and I helped out a little bit getting the barrels on. So I am out of town next week, but we should be in the air when I get back.
One nice thing, Gibson felt they did all of the work to justify an overhaul vs. just a repair on the cylinders, so in terms of a log entry that is a positive.
Another interesting point apparently Lycoming on the newer versions of this motor have included another oil ring lower on the piston skirt. Presumably to reduce oil consumption. Strange design though you cannot use a normal ring compressor to get the cylinders on. You have to compress the upper rings, fit the cylinder over, move the compressor, recompress, then fully fit the cylinder. Anyway, even if they say otherwise Lycoming is making some changes to address some of the issues, especially blow-by.
One nice thing, Gibson felt they did all of the work to justify an overhaul vs. just a repair on the cylinders, so in terms of a log entry that is a positive.
Another interesting point apparently Lycoming on the newer versions of this motor have included another oil ring lower on the piston skirt. Presumably to reduce oil consumption. Strange design though you cannot use a normal ring compressor to get the cylinders on. You have to compress the upper rings, fit the cylinder over, move the compressor, recompress, then fully fit the cylinder. Anyway, even if they say otherwise Lycoming is making some changes to address some of the issues, especially blow-by.
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Modified for clarity. Outside of that, an extra oil control ring could backfire into greater blow by, makes me wonder what fundamental design error they are try to mask.
Checkout_my_Six
Touchdown! Greaser!
careful....it might not be blow-by that the ring is there for.....could be a skirt guide to prevent slapping?
Dr. Ted?
Dr. Ted?
careful....it might not be blow-by that the ring is there for.....could be a skirt guide to prevent slapping?
Dr. Ted?
That's my point, the oil control ring itself won't do anything about blow by as a seal, and since the upper rings use a slight film of oil to seal, adding an extra oil control ring could prove negative to blow by. Considering that and millions of engines do just fine without such an oddity, it makes me wonder what the fundamental error is that requires a poor fix.
Alexb2000
En-Route
Thanks for the mod, not enough coffee today.
Anyway, seemed strange to me also, I am just repeating the reasons the mechanics were given. These motors do use some oil, not like a radial, but certainly more than a Continental. I am not sure how an oil control ring would be good for piston slap?
Because it would be a spring installed in a slack space that gets leveraged against. It really sounds like a poorly designed piston that they got the wrist pin location/mass balance wrong on. The connecting rod design could also be participatory.
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Checkout_my_Six
Touchdown! Greaser!
think....damping/spring vs. seal.
Alexb2000
En-Route
think....damping/spring vs. seal.
I understand the concept, I just don't see how it will work that way. You have a ring lower on the skirt near the wrist pin so you have the greatest lateral force on an oil control ring which wouldn't be good for spring force vs. a compression ring, but you are not below the wrist pin where piston slap would occur. Additionally the way to fix piston slap would be to reduce the clearance between the piston and cylinder, which would be easier to do vs. turn another slot, drill it, and source another part number.
Also on these ~650 hour cylinders, zero sign of piston slap.