No wthat I have come down (just a bit) off of my high from the first flight, i am starting to realize that I have lots of questions.

I recall my test pilot pointing out that there were some fluctuations in the oil pressure reading,  (lycoming O-235L2C with Catto prop) during cruise  I recall (vaguely) noting that the pressure would fluctuate between say 49psi and say 52 or 53 (I do have a logging Dynon, I just have not installed the datalogging software onto my laptop nor downloaded any of the initial flight data)

Is it reasonable to see some fluctuations in the pressure because the Dynon is accurate and sensitive or is it indicative of a clogged fliter screen, etc?  how much fluctuation is too much?  I dont want to nitpick my overhauler if this is "normal" for a new engine with <10 hours since major or if I 'm used to a steam gauge oil psi and now have a instantaneous reading Dynon) BTW, CHT's, EGT's and temps were all solidly in the green

-Brad Cohen

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Before worrying about small pressure fluctuations, Brad, I would worry about the oil pressure numbers you are getting. According to the Manual http://hhh.gavilan.edu/hspenner/Main/Manuals/Lycoming-Engines/Opera... you should have a max oil pressure of 90 psi and a minimum of 60. At hot idle it can be as low as 15 psi but I am presuming you are talking an oil pressure in the high fourties to low fifties in flight and that is below limits. If your freshly built engine is not holding minimum oil pressure it certainly will not hold it when it has a bunch of wear on it.

I do not know the L2C variant very well. Many Lycomings have externally adjustable oil pressure but I do not know if yours is one of them.

Also, do not trust an electronic oil pressure indication without cross-verification. Try installing a known accurate mechanical gage temporarily and see what indications that gives you. You may have a bad pressure sender right out of the box (it happens) or your EMS may be kinda funky. Tap the mechanical gage into the same spot the electronic one is sensing from either by putting a T fitting in to hook up both sensors or else just remove the electronic sensor and use only the mechanical gage for a flight or two.

Oil pressure will vary with temperature. Cold engine higher than hot engine. Oil pressure varies with engine rpm, idle (lower) vs. take-off or cruise power setting (higher). Variations in the Dynon digital read out is visible to your eye as the numbers change. The same variations in pressure are there but the old steam gauge is bouncing around in the panel, but its needle movements reacting slower are not as noticeable to the eye. Never rule out a defective oil pressure sender on the motor.

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