Oil analysis

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4RNB

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4RNB
Oil2.PNG My engine is about 230 ish hours past TBO, certainly past time. Top end was all new within about 300 hours. I think it is running well. Minimal to no oil burn, less than a quart added since last oil change. Compressions last month were good, nothing showed up in oil filter. I do not have CHT monitor. A little while ago Blackstone called me on the phone to discuss my oil report...What do you think? It is really just one isolated data point, I expect to do nothing other than follow the oil.
 
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4RNB said:
My engine is about 230 ish hours past TBO, certainly past time. Top end was all new within about 300 hours. I think it is running well. Minimal to no oil burn, less than a quart added since last oil change. Compressions last month were good, nothing showed up in oil filter. I do not have CHT monitor. A little while ago Blackstone called me on the phone to discuss my oil report...What do you think? It is really just one isolated data point, I expect to do nothing other than follow the oil.
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That is a surprising report IMO. I would freak out if they called me also.

Get your mechanic to do another leak down and a boroscope seems like a good idea.

IMO and in hindsite it seemed like a bad idea to put cyls on a motor with that many hours. But you know what hindsite is, worthless just like my post.

I'd do another leak down while you watch. Then maybe fly it for a while longer and then send another sample in at about 10-12 hours.

FWIW I change my oil closer to 60 hrs.
 
How did your oil filters look.

My old flight school and my current employer always cut them and look for metal
 
4RNB said:
It is really just one isolated data point,
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Is this your 2nd report with this engine? Or were there more reports under a different client ID ?
Was the sample taken in the identical manner and location as the previous sample?
Have there been any changes in how you maintain/operate the engine since the last report?
 
Gary Ward said:
That is a surprising report IMO. I would freak out if they called me also.

Get your mechanic to do another leak down and a boroscope seems like a good idea.

IMO and in hindsite it seemed like a bad idea to put cyls on a motor with that many hours. But you know what hindsite is, worthless just like my post.

I'd do another leak down while you watch. Then maybe fly it for a while longer and then send another sample in at about 10-12 hours.

FWIW I change my oil closer to 60 hrs.
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What is a leak down?
I bought the plane this way, seemed like a bargain.
 
In 20 years Blackstone never called me. I'm surprised they called about this with just one prior sample. I suspect that like Bell mentioned, there are prior reports under a different name.

I'm surprised a mechanic suggested a top end 70 hours from TBO. That seems a bit... optimistic to me.
 
BladeSlap said:
How did your oil filters look.

My old flight school and my current employer always cut them and look for metal
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The filter looked good. I was present when the oil was done, there was no visible metal.
 
donjohnston said:
In 20 years Blackstone never called me. I'm surprised they called about this with just one prior sample. I suspect that like Bell mentioned, there are prior reports under a different name.

I'm surprised a mechanic suggested a top end 70 hours from TBO. That seems a bit... optimistic to me.
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Not sure what the full background of this was. I was not an owner at that time. I am not aware of Blackstone having ever performed an analysis on this plane. There was one prior report in the stuff I got when I bought it, from a different lab, pre cylinder change.
 
Bell206 said:
Is this your 2nd report with this engine? Or were there more reports under a different client ID ?
Was the sample taken in the identical manner and location as the previous sample?
Have there been any changes in how you maintain/operate the engine since the last report?
Click to expand...


It is my 2nd report, third or so oil change. I was told to not check so close to new cylinders so did not worry about it for the first one. For the 2nd one, they told me to watch copper, they had some minimal concerns expressed that could be attributed to newish cylinders.

I did not see the first sample be drawn.

I was nearby for this sample being drawn, A/P said he let oil flow for 30 seconds then caught the sample before putting a hose on. I thought he put the hose on and got the sample right away from an engine that had been flying 15 minutes prior. Blackstone did not think that the previously used hose would contaminate a sample and made no comment when I told them I thought this was the first oil thru a hose.

I trust my A/P when he said 30 second flow first, but then he texted that maybe there could have been some contaminants.
 
4RNB said:
I did not see the first sample be drawn.
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Unless you can ensure the 1st sample was taken in the same manner as the 2nd sample you may want to go with a 3rd sample after the same flight time. Just be sure the 3rd sample is pulled the same as the 2nd. Differences in how the oil is sampled can create variances especially with only one previous report.

FYI: I prefer to draw samples out from the top when ever possible vs draining as it is harder to ensure sample consistency.
 
I wouldn't jump to any conclusions based on this one sample, particularly if a close examination of the oil filter looked fine.

I'd run it another 30 hours and check again.

And get an engine monitor. It is the most direct way to be sure the engine doesn't have imminent issues.
 
Did the plane sit for a few weeks between flights during its 29 hours?
 
Domenick said:
Did the plane sit for a few weeks between flights during its 29 hours?
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Sort of. The plane was in for annual, sat in shop for a while, 2-3 weeks.
 
2-3 weeks could be enough time for a bit of oxidation to form in cylinders which is then wiped off and into the oil when the plane is started. Personally, I wouldn't worry about it and would continue to fly as usual.

Did you realize the oil analysis you posted has ALL your contact information?
 
Domenick said:
2-3 weeks could be enough time for a bit of oxidation to form in cylinders which is then wiped off and into the oil when the plane is started. Personally, I wouldn't worry about it and would continue to fly as usual.

Did you realize the oil analysis you posted has ALL your contact information?
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No, and thank you. Fixed.
 
RyanB said:
A compression test.
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4RNB said:
What is a leak down?
I bought the plane this way, seemed like a bargain.
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A leak-down test, also known as a differential pressure test, is when the cylinder is pressurized and the inflow/outflow are compared. What makes it useful is that air loss can be traced to its source: if you hear the air escaping through the breather, the rings are leaking; through the exhaust, an exhaust valve, through the throttle body, an intake valve.
I still have my old Snap-On tester, it has a warning to watch the prop when you connect the air!
Different from a dynamic compression test, and both should be used.
 
Kenny Phillips said:
A leak-down test, also known as a differential pressure test, is when the cylinder is pressurized and the inflow/outflow are compared. What makes it useful is that air loss can be traced to its source: if you hear the air escaping through the breather, the rings are leaking; through the exhaust, an exhaust valve, through the throttle body, an intake valve.
I still have my old Snap-On tester, it has a warning to watch the prop when you connect the air!
Different from a dynamic compression test, and both should be used.
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If I am not leaking oil is there anything to be gained doing this test?
 
It is another diagnostic tool.

Suppose you have a broken ring :

You would get a low reading ( 50/80 ?) and air would escape through the

Breather and Oil Filler.

The broken ring may also score the cylinder wall and allow oil to foul the

plug (mag drop) and increased oil consumption on that one cylinder.

The scored cylinder wall will chew up your aluminum piston as well.

You may find iron, chrome or aluminum in your oil filter or by draining

oil through a paint strainer.

Oil Analysis is still another diagnostic tool best utilized in combination

with other tools when analyzing.

You WOULD want to identify the source and correct one cylinder rather

than have it progress and you have an engine full of metal needing a Major O/H.
 
4RNB said:
If I am not leaking oil is there anything to be gained doing this test?
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Cylinder "leak down" has nothing to do with oil leaks.
It's about how much air can leak out of the combustion chamber in the cylinder past the rings / valves - an indication of low compression / high blow by / burned valve .

The aircraft equivalent of a compression test.
 
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