TIO540-AJ1A Lycoming Cylinder Advise

Alexb2000 said:
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.
Click to expand...

It stabilizes the piston square in the bore through the flop at the top so the compression rings stay square in the bore. The ring can only provide a 'perfect seal' when it is square in the bore. Any 'rocking' of the piston creates a "circle in an ellipsoid" relationship which will break the seal and allow bypass.

By putting an oil control ring lower on the skirt (best below the wrist pin), it will minimize the rocking force of the piston. They need to redesign the piston and potentially connecting rod to affect a correct fix.
 
Henning said:
It stabilizes the piston square in the bore through the flop at the top so the compression rings stay square in the bore. The ring can only provide a 'perfect seal' when it is square in the bore. Any 'rocking' of the piston creates a "circle in an ellipsoid" relationship which will break the seal and allow bypass.

By putting an oil control ring lower on the skirt (best below the wrist pin), it will minimize the rocking force of the piston. They need to redesign the piston and potentially connecting rod to affect a correct fix.
Click to expand...

What? If you were trying to correct piston slap reduce the piston to bore clearance in the manufacturing process, done and done. I have never seen an example in any piston engine where adding another oil control ring reduced piston slap. I have never seen any ring below the wrist pin either. Do you have an example?

I still think this is exactly what it seems, you have an oil squirter coating the bottom of the piston and the bore in this engine, the existing oil control ring was overwhelmed on the down stroke so an additional oil control ring was added. This engine was modified from earlier versions with the addition of the squirters and part of that seems to be a coincident blow by problem, even with a factory separator, and new tolerances.
 
Ok, so the over oiling is the design failure requiring extraordinary measures. Makes sense, I wasn't aware.
 
Henning said ":::It stabilizes the piston square in the bore through the flop at the top so the compression rings stay square in the bore. The ring can only provide a 'perfect seal' when it is square in the bore. Any 'rocking' of the piston creates a "circle in an ellipsoid" relationship which will break the seal and allow bypass."

By putting an oil control ring lower on the skirt (best below the wrist pin), it will minimize the rocking force of the piston. They need to redesign the piston and potentially connecting rod to affect a correct fix. __________________




Alexb2000 said:
What? If you were trying to correct piston slap reduce the piston to bore clearance in the manufacturing process, done and done. I have never seen an example in any piston engine where adding another oil control ring reduced piston slap. I have never seen any ring below the wrist pin either. Do you have an example?

I still think this is exactly what it seems, you have an oil squirter coating the bottom of the piston and the bore in this engine, the existing oil control ring was overwhelmed on the down stroke so an additional oil control ring was added. This engine was modified from earlier versions with the addition of the squirters and part of that seems to be a coincident blow by problem, even with a factory separator, and new tolerances.
Click to expand...

I will chime in with what I feel is pertinent to this topic.

First, since this is a motor where thousands were built and the basic design has been proved to be sufficient and the motor has not been bored/stroked or any other geometry has been altered, then a redesign of the piston /crank /rod alignment is not needed or required...

There are alot of motors built with oil control rings on the skirt and below the wrist pin. Most of those applications are on inline ( pistons are moving straight up and down). To a lesser extent that style piston is used in motors with a ( V ) configuration and the vast majority are in industrial applications which use long strokes to gain maximum torque.. That reciprocating action will cause piston rock in the cylinder bores mainly because of the sheer weight of heavy pistons and rods and the rod / crank angles involved with long stroke motors.



Our aircraft motors are horizontal motors and believe it or not gravity does influence pistons that are riding in the cylinders.. Also remember, aircraft motors have pistons with rather short skirts and that does not help the piston rocking action... Henning has it right that pistons need to be perfectly square in the bores for the rings to operate properly.. By adding a lower ring, it will help the stability and squareness of piston, and that ring assembly does not need to be a true oil control ring but have enough stiffness to prevent piston rock and act as a preliminary oil control device... On most turbo motors the piston oiler is needed to spray on the inside bottom of the piston dome to help carry away the extra heat the turbo imposes on it.. That oil spray in pretty well aimed at the area on the piston but some does get on the cylinder walls when the piston is close to and at top dead center so the lower oil control /stability ring does become effective for scraping excess oil and reducing oil consumption..

Piston to wall / cylinder clearances are VERY hard to alter or reduce since the operating temperature range does not change much from the original design.... At face value it looks like reducing that clearance would be simple way to cure piston rock but unless you use different piston materials with smaller expansion rates and cylinders were drastically redesigned to maintain less thermal expansion /contraction rates at all operating conditions changing piston to wall clearances are not a viable workaround method..., Piston to wall clearance is always set to the greater clearance as closer tolerances could cause pistons to stick in the bores... You do NOT want that. The trade off is the piston will not be as stabile.


As the one poster pointed out. loading a piston with upper and lower rings will be a little more difficult . cylinders usually have a large chamfered angle on the bottom and that will let you "walk" the lower ring in altho since you have just used the ring compressor on the top set of rings, just repositioning it a little lower to assist the lower ring is easy.
 
Alexb2000 said:
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?
Click to expand...

The Continental engines you are comparing your oil consumption to are probably ones with a fourth ring in exactly the same place as you're describing on your Lycoming. I don't know when Continental changed to this design, but older pistons only came with three rings and had higher oil consumption rates. In an engine that was overhauled with the new four ring pistons the oil consumption is very low.

I've never quite understood what Continental's exact intentions were with the fourth ring, all I do know is that it has helped oil consumption quite a bit.
 
I have no idea whether Lycoming added a 4th ring just to the -AJ1A pistons, or if they (like Continental) have added them across the fleet. That would be interesting for someone who is more current on their parts than I am to determine.

That said, let's assume for a minute it's just the -AJ1A. As Alex said, oil consumption isn't great (compared to most Lycomings which, when in good working order, burn very little oil in my experience). Why? The top mount induction system on the -AJ1A is unique to that engine, although it does look similar to what was used on the Duke/TIO-541s and may have been copied in basis from that. Anyway, that top mount does restrict cooling air to certain parts of the cylinders. While the CHT probe may still read numbers in the "good" range, there will still be localized hot spots in the cylinders underneath the intake pipes. In some cases it's been enough to discolor the paint, even with normal/good CHTs as read by the probes.

Aside from not being great for the cylinders, this would likely contribute to increased oil consumption. As Ben said, you do not want to increase the piston size. That's not a good idea for many reasons. Adding another oil ring, though, would be easy.
 
I hate when threads are left without any closure, so here is the summary.

I just got the plane back after four months, two cylinder shops, an emergency landing, talk with an FAA inspector, and more than a few cuss words. There has certainly been a lot of frustration on my part, but I feel good about where I am now.

First, I think Lycoming has been amazingly supportive and fair. There is a lot of complaining and bad mouthing of aviation companies on here so I thought I would give a positive review to a company that I feel took really good care of me. They paid for $15K in work on an engine that is way out of warranty. I understand this is due to an SB, but I still appreciate it.

The other comment I see a lot is how high the cost of dealer maintenance are. Granted their hourly charge is more than independent shops, but still less than the Lexus dealer.

So anyway, I'll post up the bill for a few days in case this will help someone out and just to add specificity to the conversation. Anyway, thanks for the advice and comments some of you have given me they helped a lot.
 
Last edited:
Alexb2000 said:
I hate when threads are left without any closure, so here is the summary.

I just got the plane back after four months, two cylinder shops, an emergency landing, talk with an FAA inspector, and more than a few cuss words. There has certainly been a lot of frustration on my part, but I feel good about where I am now.

First, I think Lycoming has been amazingly supportive and fair. There is a lot of complaining and bad mouthing of aviation companies on here so I thought I would give a positive review to a company that I feel took really good care of me. They paid for $15K in work on an engine that is way out of warranty. I understand this is due to an SB, but I still appreciate it.

The other comment I see a lot is how high the cost of dealer maintenance are. Granted their hourly charge is more than independent shops, but still less than the Lexus dealer.

So anyway, I'll post up the bill for a few days in case this will help someone out and just to add specificity to the conversation. Anyway, thanks for the advice and comments some of you have given me they helped a lot.
Click to expand...

Glad you are back in the air....:thumbsup::thumbsup::thumbsup:
 
Alexb2000 said:
I hate when threads are left without any closure, so here is the summary.

I just got the plane back after four months, two cylinder shops, an emergency landing, talk with an FAA inspector, and more than a few cuss words. There has certainly been a lot of frustration on my part, but I feel good about where I am now.

First, I think Lycoming has been amazingly supportive and fair. There is a lot of complaining and bad mouthing of aviation companies on here so I thought I would give a positive review to a company that I feel took really good care of me. They paid for $15K in work on an engine that is way out of warranty. I understand this is due to an SB, but I still appreciate it.

The other comment I see a lot is how high the cost of dealer maintenance are. Granted their hourly charge is more than independent shops, but still less than the Lexus dealer.

So anyway, I'll post up the bill for a few days in case this will help someone out and just to add specificity to the conversation. Anyway, thanks for the advice and comments some of you have given me they helped a lot.
Click to expand...

At $1720 flat fee for the annual inspection on a 206, I would have expected those inspections at the end of the list st be covered in that amount.
 
Henning said:
At $1720 flat fee for the annual inspection on a 206, I would have expected those inspections at the end of the list st be covered in that amount.
Click to expand...

Yeah, me too. Since you brought it up I'll ask them that question. Part of this may be specific tests required by the G1000 that are not in their normal 206 inspection, I don't know.
 
Alexb2000 said:
Yeah, me too. Since you brought it up I'll ask them that question. Part of this may be specific tests required by the G1000 that are not in their normal 206 inspection, I don't know.
Click to expand...

A normal 206 inspection is around $750-$1000 at a normal price shop. Would the plane be in annual without those inspections?
 
Henning said:
A normal 206 inspection is around $750-$1000 at a normal price shop. Would the plane be in annual without those inspections?
Click to expand...

In Dallas I don't think you would see that price unless it was from a tailgater. Then they might not have all of the required tools, like a tester for the Amsafe seat belts.

I'll find out the answer to your last question.
 
Alexb2000 said:
In Dallas I don't think you would see that price unless it was from a tailgater. Then they might not have all of the required tools, like a tester for the Amsafe seat belts.

I'll find out the answer to your last question.
Click to expand...

I paid $500 less for the inspection on my 310, gear swing and all, and I was uninvolved. This was at a major FBO in the Atlanta area. They even pulled it to their hangar.
 
Henning said:
I paid $500 less for the inspection on my 310, gear swing and all, and I was uninvolved. This was at a major FBO in the Atlanta area. They even pulled it to their hangar.
Click to expand...

How many hours was the base inspection on your 310?
 
Henning said:
It was flat rated like yours, IIRC something like 25 hrs is typical on a 310.
Click to expand...

I believe I am pretty close to that hour figure. If you are at 25 hours for ~$1200 ($500 less than me) then you are paying just under $50 an hour? Seems pretty low at a large FBO in Atlanta.
 
Alexb2000 said:
I believe I am pretty close to that hour figure. If you are at 25 hours for ~$1200 ($500 less than me) then you are paying just under $50 an hour? Seems pretty low at a large FBO in Atlanta.
Click to expand...

Not really, wages in Atlanta are low, I would suspect 20 of those hours were performed by a person being paid $10 hr. I had a good bit of other work done as well, spent a total of $7k, but my point is, the inspection, all of the inspection work required, is in the flat rate.
 
Henning said:
Not really, wages in Atlanta are low, I would suspect 20 of those hours were performed by a person being paid $10 hr. I had a good bit of other work done as well, spent a total of $7k, but my point is, the inspection, all of the inspection work required, is in the flat rate.
Click to expand...

Wow. Someone making $10 an hour inspecting my aircraft for safety of flight? Hell no, I'll pay for a professional.
 
Alexb2000 said:
Wow. Someone making $10 an hour inspecting my aircraft for safety of flight? Hell no, I'll pay for a professional.
Click to expand...

No, the inspecting is the other 5 hours. The 20 is removing all the screws on the inspection plates and bagging them, removing your interior, cleaning the filth out of the belly, all the time consuming non critical stuff that shop apprentices do during the 3 years service before they take their test. Sorry if you think the IA is opening and buttoning your plane up at a major shop. Only tailgaters do that. The kid opens and cleans the plane, the IA comes out and inspects the plane showing the kid what he is looking at and for, shows them where to lubricate what, then the kid does the servicing and starts buttoning things up. That's how industry outside academia operates. Trades are tought best under mastersin practice.
 
Henning said:
I paid $500 less for the inspection on my 310, gear swing and all, and I was uninvolved. This was at a major FBO in the Atlanta area. They even pulled it to their hangar.
Click to expand...

Only doing a gear swing on a 310 is asking for a gear failure.

Alex, glad you're back in the air.
 
You must log in or register to reply here.
Back
Top