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mooney m20m


pkofman

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I received my oil sample back today after an oil change with 25 hours and 3 months on the oil

I had a pretty good report. The engine has been consistently good except this time I had tiny bit of fuel in the  oils sample and flashpoint was just below the average

is this normal and what is it an indication of when present

could this just be improper leaning that could cause that scenario

 

Thoughts.

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Think of all the ways that a sample could get contaminated...?

What was on the hands of the person taking the sample, or what container was used to get the sample....?

Fuel can get in the oil easy enough... a failed flooded start should show some results as well...

Fuel won’t stay very long in a hot oil sample... as it will evaporate quite readily...

 

A guess would be a very rich setting, followed by not getting the oil very hot, before pulling the sample...?

 

PP guess only, not qualified to judge oil samples...

Best regards,

-a-

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For my first couple of samples after purchasing the plane I had higher fuel in the oil and low flash point. I got good advice that if you follow the standard full prop, full mixture during landing you run very rich and can add enough fuel to have it show up in the oil. 

I moved to full prop but not full mixture on final (staying lean - I know, some of you will comment about go around risk) and all samples since show almost no fuel and normal flash point. 

Not sure if this is your issue but it worked great for me. I also fly out of a 6000’ airport so full rich is very rich here. 

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24 minutes ago, Danb said:

Basically yes.

I have always been in the habit of GUMP's ( mixture full rich ) pre landing check on . final.  I do enrich the mixture very very  slowly on descent  to the pattern ( leaving it lean enough in order to keep temps up) on descent . Thats just my method but it might be wrong. I would never fly the descent full rich but i am in the habit of . always full rich on final..... just in case g/a!

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3 hours ago, pkofman said:

I have always been in the habit of GUMP's ( mixture full rich ) pre landing check on . final.  I do enrich the mixture very very  slowly on descent  to the pattern ( leaving it lean enough in order to keep temps up) on descent . Thats just my method but it might be wrong. I would never fly the descent full rich but i am in the habit of . always full rich on final..... just in case g/a!

I think that is a habit you have carried over from NA use.I have found by aggressively leaning on the ground (11/12 twists of the wrist)using whatever cruise setting during descent and pattern at 20 in,while on approach etc...only time I use full rich is takeoff and climb and go arround at full power.I find less fowling of plugs doing this.

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In one of his articles on engine management Mike Busch recommends not going full rich for landing and I am beginning to adopt the practice. I understand why but because it is contrary to everything I was taught and what was standard procedure for so long I  find that it is hard to do.

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For comparison...

The NA IO550 leaned LOP in cruise at 5k’...

Will die on the ground, late in the roll out, if the mixture isn’t put back in enough...

Then you say a thankful prayer, that the gumps check That didn't get done right didn’t skip the U... :)

PP thoughts only, not a CFI...

Best regards,

-a-

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