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Check those oil screens boys

S

Sid Lambert

Well Known Member
What I thought would be a normal 2 day condition inspection turned in to much more.

O-320 - 1025.9 Hours - #1 Cylinder - AirTech 8.5:1 Pistons

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How did you determine where to look for where the piece came from? You pull all the cylinders? I sure would not have thought that lower flange is very loaded.
 
We knew it was a piece of a piston fairly soon after I found it so I decided all of them need to come off. It happened to be the second one I pulled.

I'm at a loss as to what caused it. Someone suggested shock cooling.
 
Sid, can you post a picture of the top, and edge of your piston? Let's see of there was a slight erosion of the edges. Looking for possible indicators of preignition or incipient detonation. Not saying that is it, but it is something to check that might cause higher than normal cocking loads on the piston. A cocking load would might stresses to that area.

Also can you show the thrust and anti thrust sides of the skirt to see if there is uneven pressure loading too.

The skirts are loaded, from firing pressures against the bore. The ovality of the piston does tend to try and make it round again.

It appears to have some corrosion pitting on the piston pin and scratches on the skirt. Has this engine been parked for any length of time in it's history?
 
morre info is good!

I'm also interested that you show the finger oil strainer from the sump....the one most guys either don't know exists, or don't bother checking at each oil change ( guilty of this also!)
Is this an example of chunks that are too big and heavy to be circulated, thus will never find their way to the main screen or filter?

Funny how the piston looks a bit like some we pulled from a small-block chevy .....after a season of running 5000 rpm at the oval track!
 
Damage like that usually only happens with some type of foreign object floating around the engine, like a nut or a washer. I have seen burnt Lycoming pistons and that one doesn't look like it was overheated. Check the case and look for pock marks which would indicate debris bouncing around.
 
flyboy1963 said:
I'm also interested that you show the finger oil strainer from the sump....the one most guys either don't know exists,
Click to expand...

IIRC, this is an item that is required to be checked during annual.........

43xD.d

Each person performing an annual or 100 hour inspection shall inspect (where applicable) components of the engine and nacelle group as follows:

(1) Engine section - for visual evidence of excessive oil, fuel, or hydraulic leaks, and sources of such leaks.

(2) Studs and nuts - for improper torquing and obvious defects.

(3) Internal engine - for cylinder compression and for metal particles or foreign matter on screens and sump drain plugs. If there is weak cylinder compression, for improper internal condition and improper internal tolerances.
 
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rocketbob said:
Damage like that usually only happens with some type of foreign object floating around the engine, like a nut or a washer. I have seen burnt Lycoming pistons and that one doesn't look like it was overheated. Check the case and look for pock marks which would indicate debris bouncing around.
Click to expand...

Yeah, the coloring does not look to be out of range. The attention was to the fine scratches, not as cause, but further understanding the total system.

Bob are you thinking the FOD was due to pinching between he counterweights and the lower piston? There don't seem to be any pock marks visible in the single picture? Clearly it only takes one divit. The clearance between the piston and the crank group is outside my knowledge.
 
This screen, like the oil filter should be considered during your FWF installation. Route things away so these items can be serviced without too much interference.

I pointed this screen out to an RV4 builder/owner on my field....... he pulled it at his next inspection period.
He later told me that he would never pull that screen again.....:eek:
 
Bummer Sid!

Could you tell us the part number for the crush gasket? That way we can all pre-order them in preparation for our next inspection.

Thanks!
 
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screen

I worked in the shop for a Piper Distributer in the 60's, 90% of our work was on Lycoming powered airplanes. Never saw anyone pull the lower screen. Based on that I never pulled the screen on my Pitts in 1000 hours. Obviously I now know better.
 
Hey Gil, it says in Table III to lubricate the threads. What do you use here? Fuel Lube? Thanks.
 
Why not oil? Dip your finger in just past the screen opening and surely there will be some oil there that would lubricate the threads just fine for the purpose.
 
I'll get better pictures when I go back to the hangar tomorrow. The piston is scored more than I would like and that is part of the reason to just do a top overhaul.

The foreign object comment has me worried. I wasn't planning on doing anything on the bottom end but I will of course inspect everything before doing anything.

Kyle, want to finish rebuilding my tail section while I rebuild the engine? :)
 
jrs14855 said:
I worked in the shop for a Piper Distributer in the 60's, 90% of our work was on Lycoming powered airplanes. Never saw anyone pull the lower screen. Based on that I never pulled the screen on my Pitts in 1000 hours. Obviously I now know better.
Click to expand...

Right out of the O-360 Owners Manual -

b. Oil Suction and Oil Pressure Screens
At each 100 hour inspection remove suction screen.
Inspect for metal particles; clean and reinstall.


It's worth a read. Probably not the current version, but it might be newer than your engine...:)

http://www.7ts0.com/manuals/lycoming/360/O-360-HO-360-IO-360-AIO-360-HIO-360-TIO-360_OM.pdf
 
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jrs14855 said:
I worked in the shop for a Piper Distributer in the 60's, 90% of our work was on Lycoming powered airplanes. Never saw anyone pull the lower screen. Based on that I never pulled the screen on my Pitts in 1000 hours. Obviously I now know better.
Click to expand...

Trouble is in this "hobby" its generally what you don't know that will kill you, and unfortunately, many folks don't know quite a bit. I've been in this business for 40 yrs and I still don't that much :eek:

This is another reason I continue to encourage folks to have a "professional" mechanic do your condition inspection once in a while, you'd probably be surprised at all the stuff he finds, and you'd no doubt learn something that you didn't know before. As the builder you really are the worst person to be doing an inspection.

PS: I pull sump screens on every annual and I can tell you for a fact that not everyone does (to much work).
 
If the fracture was the result of FOD you would see ping marks everywhere inside the engine and on the piston and piece that broke out. I saw that happen to a bunch of SAP pistons a few years back. Are these by chance SL parts? Maybe part of that bunch?
Anyway I don't think it happened from FOD from what I can see in the pictures and maybe it's just that it got dropped or banged during assembly and then it progressed and cracked further and broke out. If the skirt measurement gives a .010 or there abouts skirt clearance to the bore then the scoring is nothing to worry about and is actually very common and normal. I would have no problem using a piston scored like that over again if the skirt clearance was OK.
Good Luck,
Mahlon
 
I pull the screen every oil change. I put a little tuna can in the nose gear engine mount cluster to catch the little bit of oil. Takes a couple minutes to pull and 5 minutes to install and safety. Bought 100 of the crush gaskets and working through the supply. Did not know the proper torque as I just turned till tight. Thanks az_gila for posting table. Now I know.
 
Everybody talks about this oil screen, and as an earlier poster pointed out, we're often killed by the things we don't know about.

Perhaps in the spirit of greater enlightenment somebody could post a picture or pictures of the typical locations of this screen on some of the more common Lycomings (O-320, O-360)?
 
They are pretty much in the same location... bottom aft center of the oil sump.
Its at a bit different elevation on the angle vale engines because of the different induction path in the sump but it is stall aft center.
 
The only time I have seen damage to the skirt in that area that was not from a catastrophic failure was from the piston being dropped on an cylinder stud during installation of the cylinder. The color is normal for a mid time engine.
 
I usually pull my screen every other oil change. The only challenging part is re-safety wiring it. (I wish there was a little nub sticking out instead of just a hole.)
 
The difficulty many of us have with this screen is access. The FAB plate covers half of the bolt, and then it is sealed with RTV. To get it off, you have to remove the airbox, plate on the bottom of the carb or FI air handler - along with the aforementioned RTV, and then remove the screen (that's the easy part). Not saying it shouldn't be done - I've done it many times, but it's a lot of work for what is normally zero results. Easy to blow off as unnecessary after you've done it many times. I'm not saying that not doing the inspection is justified - it isn't, but that is why so many don't do it. The efficiently designed airbox many of us have that does a marvelous job of feeding our air intake system with ram air is covering up a vital inspection access point.
 
Annual Condition Inspection Powerplant dvd

This video is great to learn about all the aspects of an inspection of the powerplant during condition inspection. They perform it on an 0-360 on a Piper Archer.
http://www.actechbooks.com/products/act027/

Canadian_JOY said:
Everybody talks about this oil screen, and as an earlier poster pointed out, we're often killed by the things we don't know about.

Perhaps in the spirit of greater enlightenment somebody could post a picture or pictures of the typical locations of this screen on some of the more common Lycomings (O-320, O-360)?
Click to expand...
 
Just as a point of reference, I claim to know far less than Walt, and I have participated in owner assisted annuals or condition inspections for the past 14 years. I'm not knocking anyone I 'assisted' but the first time I saw a screen pulled was this past fall.

From what I've learned listening to Mike Busch at OSH this summer, and what I've learned observing, the screen picks up medium and big chunks of metal, the filter gets the smaller metal pieces, and the oil analysis identifies the dissolved metal. I was pleased to see the IA I assisted this year pull the screen and if he didn't do it on his own, I knew to ask him to do it.

It's my hindquarters in the plane every time it leaves the ground and I'm really interested in knowing everything I can about the health of the engine. So from here on out that finger screen in the sump will be checked at every annual.
 
Scott Hersha said:
The difficulty many of us have with this screen is access. The FAB plate covers half of the bolt, and then it is sealed with RTV. To get it off, you have to remove the airbox, plate on the bottom of the carb or FI air handler - along with the aforementioned RTV, and then remove the screen (that's the easy part). Not saying it shouldn't be done - I've done it many times, but it's a lot of work for what is normally zero results. Easy to blow off as unnecessary after you've done it many times. I'm not saying that not doing the inspection is justified - it isn't, but that is why so many don't do it. The efficiently designed airbox many of us have that does a marvelous job of feeding our air intake system with ram air is covering up a vital inspection access point.
Click to expand...

I think you are mistaking the oil sump screen for the carb bowl drain plug.
 
Don said:
Just as a point of reference, I claim to know far less than Walt, and I have participated in owner assisted annuals or condition inspections for the past 14 years. I'm not knocking anyone I 'assisted' but the first time I saw a screen pulled was this past fall.
Click to expand...

I certainly don't mind when owners want to hang around and learn something about their airplane, but I don't do "owner assisted" annuals for the following reasons, there are a number of problems associated with this form of inspection.

1) Owner is good at taking things apart, then leaves and I have to put it back together, much harder when I didn't take it apart (no 2 RV's are the same).

2) Owner takes something apart and doesn't say anything and doesn't write it down, I have to "discover" these things on my own. This is dangerous.

3) In reality it takes much more time to answer a million questions and teach than just do it myself.

In the certified world I associate "owner assisted" annual with someone to cheap to pay for a real annual and is really just looking for a signature in the logbook.
 
Walt said:
I certainly don't mind when owners want to hang around and learn something about their airplane, but I don't do "owner assisted" annuals for the following reasons, there are a number of problems associated with this form of inspection.

1) Owner is good at taking things apart, then leaves and I have to put it back together, much harder when I didn't take it apart (no 2 RV's are the same).

2) Owner takes something apart and doesn't say anything and doesn't write it down, I have to "discover" these things on my own. This is dangerous.

3) In reality it takes much more time to answer a million questions and teach than just do it myself.

In the certified world I associate "owner assisted" annual with someone to cheap to pay for a real annual and is really just looking for a signature in the logbook.
Click to expand...

Walt,

I am sorry your owner assisted annual experience has been so bad. I don't think items 1 &2 have ever been an issue in my limited experience; two planes, 14 years, and 16 annual or condition inspections with 4 different IAs. Normally I remove everything before the IA starts, assist or do the repairs that are needed, and reassemble the plane. As for it taking longer to explain stuff, I normally pay by the hour so item 3 is something I am paying for and I never met an IA who seemed to mind explaining what he was doing and why.

As for saving money on certified and experimental aircraft, I could argue it either way. On the one hand, I probably save some labor taking thing apart and reassembling them on REAL annual. I also know IAs that do so pretty darn minimalist annuals and charge less than I pay to do the whole thing. I have never used one, but if saving money was my intent, I could save more and do less using one of them.

As for being too cheap to pay for a real annual on my certified plane, that simply isn't the case with me, and it sure felt like a cheap shot when you suggested it as a fact of life across the board.
 
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Don said:
Walt,

As for being too cheap to pay for a real annual on my certified plane, that simply isn't the case with me, and it sure felt like a cheap shot when you suggested it as a fact of life across the board.
Click to expand...

OK, maybe a little harsh and I apologize to you, certainly this is not always the case. Half the certified airplanes on our field I wouldn't be interested in flying in due to the poor condition of them and lack of maintenance, many are owner maintained.
 
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I have done quite a few Condition inspections on RVs and my policy is that the owner is required to assist.
I have found that almost all RV pilots who need a condition inspection done fall into one of two categories; a non-builder who bought the plane, or a builder who knows a second set of eyes can be a good thing.
The reason I require the owner to assist is to disassemble the cowling, interior and inspection plates. Since all RVs are different, the owner typically knows how to do this and keeps me from accidentally damaging something. I feel that non-builders need to learn more about their planes and a condition inspection is the perfect time to do that. I use a very detailed checklist for each type of RV and we go through it together, which doesn't seem to take a lot of additional time, since it is inspecting, not building.
I like to make sure the owner leaves with at least some extra knowledge about his plane, along with a thorough condition inspection.
 
Makeing beakfast..

Some times you just don't know for sure. When you put things together handling parts is very important. Have you ever dropped an egg while making breakfast or a sparkplug while installing it? Have you ever hit your thumb instead of the nail with the hammer? Sometimes a casting is not gust right and gets through "Q.C.". A very close look is often needed just to guess. Bases on a picture that is all you can do in most cases. Have you ever put a piston on a rod and bummed the prop, pulling the piston skirt against the crankcase or a small area of the skirt against a case bolt or stud?
Short of sending this to a lab and that is only doing the best guess in some cases. It has all the hallmarks of impact damages or casting fault. Either way or any of a half dozen ways, it is a good time to take the top end off and do a close look-see and "T.O.". Oh the normal wear on the cylinder walls is at 90* to the wristpin run line. Hold your hand up with it loosely closed, then move it back and forward. That's why we call it a wristpin. This wear will make the cylinder wall oval in that respect. Good luck with the "T.O." Yours as always R.E.A. III #80888
 
Scott Hersha said:
The difficulty many of us have with this screen is access. The FAB plate covers half of the bolt, and then it is sealed with RTV. To get it off, you have to remove the airbox, plate on the bottom of the carb or FI air handler - along with the aforementioned RTV, and then remove the screen (that's the easy part). Not saying it shouldn't be done - I've done it many times, but it's a lot of work for what is normally zero results. Easy to blow off as unnecessary after you've done it many times. I'm not saying that not doing the inspection is justified - it isn't, but that is why so many don't do it. The efficiently designed airbox many of us have that does a marvelous job of feeding our air intake system with ram air is covering up a vital inspection access point.
Click to expand...

You must be think of a different plug... the only thing that is close to the finger screen plug on a vertical induction Lyc is the engine control cable bracket. The only issue it causes is that since the top plate of it is directly below the plug, any oil that drains out runs all over when it runs onto the top of the plate.

The control bracket, along with exhaust system hangers does add some challenge to accessing the plug but is is still not that difficult. I usually find it more of a challenge redoing the safety wire, than removing and reinstalling the plug.

Edit: Looks like Walt beat me to it...
 
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Scott Hersha said:
Oops...... you're right Walt! The carb screen is no fun......
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The carb screen is opposite the fuel inlet, the plug on the bottom is just a bowl drain plug.

As long as we are talking about screens, everyone should be pulling carb and FI inlet screens at each annual as well as oil screens.
 
You Are a class act Walt. I shouldn't be trying to respond to forum posts from my hotel room 1000 miles from home and my hangar..... I'm just bored....
 
Mahlon,

It was not FOD for sure. I found a crack on the other side in the same place.

I don't know what SAP means. They are airTech 8.5:1 pistons.

mahlon_r said:
If the fracture was the result of FOD you would see ping marks everywhere inside the engine and on the piston and piece that broke out. I saw that happen to a bunch of SAP pistons a few years back. Are these by chance SL parts? Maybe part of that bunch?
Anyway I don't think it happened from FOD from what I can see in the pictures and maybe it's just that it got dropped or banged during assembly and then it progressed and cracked further and broke out. If the skirt measurement gives a .010 or there abouts skirt clearance to the bore then the scoring is nothing to worry about and is actually very common and normal. I would have no problem using a piston scored like that over again if the skirt clearance was OK.
Good Luck,
Mahlon
Click to expand...
 
Sid Lambert said:
Mahlon,

It was not FOD for sure. I found a crack on the other side in the same place.

I don't know what SAP means. They are airTech 8.5:1 pistons.
Click to expand...

SAP = Superior Air Parts.

When you say "the other side", what do you mean? The opposite side of that piston, or a piston in the opposite cylinder?
 
The other side of the same piston.

I honestly can't decide if I should rebuild the entire engine or just do a top overhaul.
 
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