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Last night I completed the oil change on my 912ULS. After finishing and turning on the Dynon Skyview, reported oil pressure was 4 PSI which it always says when the engine is off. When I started the engine, it started up very easily and ran smoothly but the reported pressure remained at 4 psi for about five seconds and then immediately climbed to 75. I let the engine warm up and it ran smoothly with a good mag check, and when oil was 105 degrees the pressure was 60 psi.

I'm wondering if that's normal or a sign that something is amiss. I never removed any of the oil lines nor did I ever touch the prop without full oil.

The procedure I used was to warm up the engine (oil got to 110 degrees), then turn everything off, remove the oil cap, and turn the prop a lot to repeatedly burp the engine. Then I removed the drain bolt and let the oil drain out, and meanwhile I removed and replaced the oil filter. Then I put the drain bolt back and torqued it, and I removed and checked the magnetic plug but it was very clean so I put it back and torqued it. Then I filled the canister with a bit under 3L of new oil, put the cap back on, turned the prop a bunch, then started the engine.
  • Re: Concerned about oil pressure after oil change

    by » 7 years ago


    Sure sounds OK to me. My only observations are:
    1) To efficiently "burp" your 912ULS, you don't normally need to "turn the prop a lot" -- high prop rotational speed during "burping" does not facilitate the process. If you pause your slow hand-rotation of the prop for a second or two at its maximum compression point, you will expedite the transfer of oil from the crankcase to the oil tank. On my RV-12, I usually hear the "burping" start after some 8 - 14 cylinder compressions (not prop revolutions) -- depending on temperature and time between engine operations.
    2) Quickly spinning the prop "a bunch" after the oil change serves to fill the oil pump, oil filter, and oil lines with fresh oil -- a good thing. On some oil changes, I may have the spark plugs removed so the prop can be readily spun by hand. With spark plugs installed, its a bit harder to quickly spin the prop by hand.
    3) A 5-second delay in seeing oil pressure does not seem to me to be excessive particularly if the ambient temperature is cold or you have a remotely-mounted Oil Pressure sensor. However, I like to see some indication of oil pressure when I hand-spin the prop after an oil change.

  • Re: Concerned about oil pressure after oil change

    by » 7 years ago


    Hi Ed,
    You may have had a bit of air and it just worked its way out. So long as it's good on the next start I wouldn't worry. The 4 psi when could is almost always the sender. In your case I don't see it as a problem.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: Concerned about oil pressure after oil change

    by » 7 years ago


    I believe that most of us with Skyview sensors typically see single-digit values (e.g., 4 psi, etc.) when there is little or no pressure in the system. Apparently, this is just a characteristic of the sensor design and not indicative of a problem.

  • Re: Concerned about oil pressure after oil change

    by » 7 years ago


    Thanks guys, that's reassuring. I'm just being cautious; this was my first aircraft oil change.

  • Re: Concerned about oil pressure after oil change

    by » 7 years ago


    The only thing not addressed in the /oil filter change I see was missed, this is in the Aircraft maintenance manual ,
    8. Fill the new oil filter half full with new engine oil before installation 9. Install the new oil filter. Just did my own first oil change so I remember seeing this! Flight fun fly safe .

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