High oil temperature in Lycoming and Continental engines

Hi John,
Here are the photos of my home made oil cooler for the Continental O-300. It actually takes about 15 degrees out of the oil on these hot summer Texas days.



Take a close look. This is a Rapco vacuum pump cooling shroud!

This customer installed the Rapco vacuum pump cooling shrould around his oil filter. Neat idea and it reduced oil temperature by 15 degrees!

Removing magnetism from Austenitic Stainless steel

I bought some 304 stainless steel tubing for building a fuel cell and found that even though it was touted as being austenitic, it had a magnetic field down the welded seam (nowhere else). I had tested the tubes with a neodymium magnet and saw where the field was. Will your degausser remove the magnetic field?



The degausser will not prevent the austenitic stainless from being magnetic. It will remove magnetic fields excepting the earth's magnetic field.

Austenitic is slightly magnetic when cold worked. In the fully annealed condition it is non-magnetic.

Any austenitic (300 series) stainless steel which is magnetic can be returned to non-magnetic condition by stress relieving to 700-800 degrees C. It then reverts back to its fully annealed condition and is softer and weaker. There may be other issues with annealing so the best thing to do would be to engage a metallurgist.

The degausser will remove an artificial magnetic field from a iron object, leaving just the earth's magnetic field. By testing with a magnet you have probably slightly magnetiized the weld area (stressed area).

Prop strike teardown recommendation

To answer the question "should the engine have been torn down for a more complete inspection"?

My recommendation has always been to do a tear down inspection for the following reasons:

1. After a prop strike there is rightful concern about the airworthiness of the engine. This concern can only be answered by inspection and not by hope, prayer, or opinion.

2. Having a shop that has performed approximately 1 prop strike inspection each month for some 20 years, I still cannot tell you which prop strikes cause damage and which ones don't without an inspection. This has taught me that the preceived "severity" of the propeller strike is not a criteria for deciding which engines should be inspected and which ones need no inspection.

3. I personally didn't tear down my engine after I hit the towbar with the propeller and sent it flying across the airport. But then we did one on a Navajo that hit a plastic caution cone that had damage -

4. Engine mounts can also be damaged. That said, my opinion is based on my personal experience and others have views that conflict with mine based on their experience and judgement. I could be wrong.

I have spend many year pondering how to inspect the engine without tearing it down and I have never come up with an adequate method. Your question as to signs to look for - I don't know.

The pilot and his single passenger were fatally injured Cessna 210L, N5060V  "The crankshaft contained a fracture that intersected the aft fillet radius for the propeller flange and the cylindrical portion of the crankshaft located aft of the aft fillet radius."


"According to an airplane mechanic who had worked on the accident airplane,N5060V had been involved in a propeller strike incident in which the propeller was damaged. The propeller was removed and sent for an inspection and overhaul. The mechanic reported, "The owner of Gallatin Flying Service, [name of owner], was  informed and advised of the need to do a teardown of the engine to check for damage. He would not approve doing this. We [the maintenance staff] did a run out check on the  crankshaft, aft of the propeller flange, with a dial indicator. No defects where noted at that time."

Re: question about oil filter examination

Thanks very much for your help John.

Here's an update:

In advance of reading your response I actually rinsed off a few pleats into a glass container with solvent.
Note that I picked pleats where small visible accumulations had gathered which I suspect relates to oil flow patterns through the filter.
I then dried the material which consisted of a few very tiny particles of varying color - tan, brown, gray.

None of it is magnetic.

I then took it out and squished it between my fingernails. It all mashes up effortlessly into a fine powder.
My feeling as therefore that this represent tiny bits of carbon or combustion products.
I think the shiny things I'm looking at are microscopic gray carbon bits.

Steve,

Black and gray particles that you can squish between your fingernails are pieces of carbon, sludge and lead oxides and are normal.

Small shiny bits you can spread them onto a microscopic slide and and add a drop of Drano mixed with water. Look carefully under the microscope. If it is aluminum it will start to fiz and dissolve.

Re: question about oil filter examination

John,

I have read your knowledge base post on oil filter examination and wondered if the author (or other knowledgable person) could answer a quesion for me.
I routinely open my filters. Under casual observation nothing much is evident. The last couple of times I looked a little closer than usual and in bright sunlight. In the bright light I can see scattered microscopic shiny bits. They are so tiny you wouldn't see them other than by their reflection. I have been told that this represents an inconsequential finding, possibly microscopic bits from plating - normal wear finding. Would you agree?

I also find little bits of debri here and there, non-metallic in appearance and non-magnetic. It has the appearance of a tiny quantitiy of sand which may be just what it is.

I have not found anything large, magnetic, or otherwise scary looking.

Ultimately my question I suppose is; Should anything at all be visible on the pleats? I would imagine that filtering oil through there for 40-50 hours your gonna find something. That's what it's there for, right?

Thanks
Steve



On my other web site I mention how to use sunlight to see microscopic particles in the oil। http://www।cancutter.com/how_to_inspect.htm. These might be small bits of bearing material.

Often with mechanics I don't agree with their theory but I do agree with their actions because often it is based on years of practical experience.

It is not normal for parts in an engine to shed metal particles. Possibly during initial break-pin (when you have surfaces getting to know one another) you can have a small amount of particles. From then on normal wear on surfaces does not generate particles. So much for theory. Now what do you do about it?

If the particles are very small and not many then typically the answer is to keep checking and make sure it doesn't get worse.

For your stuff that looks like sand. Try to squish the particles between two pieces of glass or your finger nails. Sand will not squish and will scratch the glass or your finger nail.

By examining the pleats you aren't going to find cam lobe or cam follower material in the early stages of failure. Better to rinse the pleats with solvent and a toothbrush. Drain the liquid through a coffee filter land let dry. Place a magnet under the coffee filter and move all of the iron to one side. If there is enough fuzz sticking to your magnet to cover the end of a stick magnet then inspect the cam lobe and follower. You will get a much better idea as to the amount of stuff that is in your filter using this method.
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John Schwaner
john.schwaner@gmail.com
http://www.mechanicsupport.com/

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