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We all know the required prop , burp, and check oil ritual before starting a 912. But if I've only shut down for an hour I certainly don't do the prop ritual again before restarting. In fact if I come back and restart during, say, the next four hours, I don't.

Does anyone have an opinion or knowledge regarding how long is TOO long an interval interval to safely ignore the prop/oil procedure ?

Also: I figure if I check the oil level and it is exactly where it recently was AFTER a prop-burp-checklevel at same oil temp, that itself means there's no oil where it shouldn't be and no need for burping. Any comments on that theory?
  • Re: How long between starts needs prop oil burping?

    by » 9 years ago


    Once a day at first start should be fine.
    Oil doesn't leak back into any cylinder that fast and if you were burning oil, puking it out the vent tube or leaking oil inside the cowl it would either be coated in the exhaust pipe or all over the bottom of the plane. I find no one ever seems to look at these two places for oil residue and yet they can be the most telling and the quickest to alert that there may be an issue short of pulling the cowl.

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


    Thank you said by: Al C

  • Re: How long between starts needs prop oil burping?

    by » 9 years ago


    "..Once a day at first start should be fine..."

    Thanks,
    I guessed that... but nice to have reassurance.

    How about my other lazy-guy theory? :unsure:
    The one that says, for example---
    "It's been two days since I've flown, but the oil after burping two days ago was EXACTLY 1/8th inch below the full line at room temp, and this morning at same hanger/room/engine temp is at the exact same place on the dipstick. So I know NO oil is anywhere it shouldn't be -- is all in the holding tank -- and I don't need to burp this morning." :unsure:

    Other two questions ..... issues of curiosity and education:
    # Has anyone seen or know of credible reports of anyone ever actually in practice damaging their Rotax by failing to burp? If not, I know that wouldn't be reason to discard the proceedure, but on the other hand if there are actual instances of damage caused that way, just a re-enforcement of the habit.

    # I've never completely understood the issue of where the oil potentially drains to that makes us need to burp. Sure I understand if there's oil in a cyclinder it's non-compressible and would be real nasty to have in there if the engine started.
    But wasn't there something about valve lifters in that "you better burp" story?

    BYW:
    Once when my co-owner, Mike, was doing the burp routine someone walked up and asked --
    "Trying to hand-start it?"
    He replied with a straight face --
    "Nope, I'm winding the rubber-band." ;)

    Al

  • Re: How long between starts needs prop oil burping?

    by » 9 years ago


    My impression of the main need to burp is that it is the only way to get an accurate measure (dipstick) of the proper amount of oil.

  • Re: How long between starts needs prop oil burping?

    by » 9 years ago


    True it's the only way to get accurate oil level...but AFAIK it is _possible_ to damage engine if not burped.

  • Re: How long between starts needs prop oil burping?

    by » 9 years ago


    Hi James,

    Even if you burp it it isn't always accurate. It can lie at times. If it seems too low, but wasn't the flight before and you have no signs of leaks or oil in the exhaust then start it for a few minutes and check it again. Rotating the prop is also the way to check to see if you have oil that leaked back into a cylinder which is not compressible before you turn the key for a start and a very hard quick stop.

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


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