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I'd appreciate help on Rotax official, documented position on achieving and maintaining oil temperature, especially in cold winter regions. I know they authorize oil thermostats. Anything else?
I understand that some say add strips of tape to the radiator. Where does Rotax say that, please?
I understand that some aircraft manufacturers add doors, flaps or cowl vents to regulate oil temperature so I assume the aircraft manufacturer can stipulate how to do so. I'm actually looking for any official Rotax documentation.
Michael Coates, a primary distributor of Pipistrel, asserts that his friend, a major Rotax distributor in Australia, sees "a lot" (whatever that number is) of radiators damaged by the end of winter along the line of the tape. He calls it a fatigue crack. Have any of you seen this kind of phenomenon? Have any of you heard of a Rotax response to this kind of issue? Look in the Pipistrel Owners Forum for a fuller discussion of this question.
Let me ask again - I understand there is lot of conventional wisdom about how to increase oil temperature - I'd really lke the official Rotax position.
  • Re: Rotax On Oil Temperature

    by » 7 years ago


    Rotax doesn't say and leaves that to the Mfg or owner. Most I personally know of use a piece of 2" aluminum tape across the radiator or cooler. There may be hundreds in the US that use aluminum tape. Do not use Duct tape as the glue gets all over and hard to get off. Aluminum tape does not. A small few have doors. I have never in 20+ years heard of any issues because air still flows. It just makes the radiator a little less efficient in giving up its heat.
    Some doors and flaps work well and some also don't work well in warmer climates.

    It's up to you, but aluminum tape will not hurt your cooler.

    p.s.
    Cracks are usually caused by vibration.

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


  • Re: Rotax On Oil Temperature

    by » 7 years ago


    Roger, you are giving your opinion and observations just as Michael Coates is giving his opinions and observations. You say that Rotax doesn't' speak on this issue and you may be right, but I suspect what you are really saying is you do not know of anything Rotax says other than what is in the publications available to all of us. You often claim special knowledge of Rotax by virtue of the classes you attend and the persons you associate with, so I have to assume you don't know of any rumors or shop-floor gossip about this topic or you'd have said so.

    Here is the Pipistrel distributors own statement:
    "MichaelCoates

    Registered:08/09
    Posts: 8
    Posted 17 hours ago #13
    I am good friends with the head honcho for the Rotax distributors in Australia. He was the one who told me that he has seen a lot of cracked radiators coming back for inspection or possibly warranty replacement. He said that the cracking occurs right along the edge of whatever tape they have used to block off a portion of the radiator. He said this happens right along the edge because he can see the remains of the adhesive on whatever tape they have been using. The crack is a fatigue crack along the edge of the tape section. The differential in temperature between the area free-flowing and the area covered is what is causing the problem. If you look at the large trucks that are operating in freezing temperatures, they don't block off just a portion of the radiator, they block off the whole radiator and reduce the airflow to maintain their temperatures and a constant temperature across the radiator surface. My contact advises that he sees cracked radiators towards the end of winter because it keeps the radiator enough time to fatigue in the early parts of winter he is guessing"
    http://forum.pipistrelowners.com/post/new-virus-sw-running-too-cool-9490146?pid=1301953461
    Coates talks about warranty replacement. My hunch is that Rotax will disavow all warranties on radiators, even if it's one of theirs, and shunt it off to the airplane manufacturer. Does anyone know from personal interaction with Rotax what their position is on radiator warranty claims for a 912 or similar? If they have taken a position on warranty replacement, it must mean Rotax is aware of the issue. That is my main question here - does anyone know if Rotax is aware of the issue? The follow on-question, then, is what was Rotax response?

  • Re: Rotax On Oil Temperature

    by » 7 years ago


    BTW, I just talked on the phone with a mechanic at a Rotax Service Center and he sees no issue with the tape. He does not know of any shop-floor gossip on the issue of radiator damage due to blocking with tape. He suspects any radiator cracking is from stress due to mounting rather than any thermal stresses. He doesn't know of any Rotax pronouncements other than what is available to the general public. He said that if the airplane uses a Rotax radiator warranty is a Rotax issue but if it was modified the radiator warranty was a manufacturer issue. He has not heard of warranty claims. He is in a location that sees winter temperatures. He had no opinion on using a thermal blanket on the Rotax oil tank, but didn't oppose it.
    My purpose in posing the question initially was to see if there were official Rotax positions on the oil temperature issue. I'm comfortable that I know what they are.

  • Re: Rotax On Oil Temperature

    by » 7 years ago


    The 912 Operating manual is fairly specific about this, see page 4-7

    "Oil too cold during engine operation. - Cover oil cooler surface, maintain the oil temperature prescribed"

    Thank you said by: Andrew Dunning

  • Re: Rotax On Oil Temperature

    by » 7 years ago


    In my club, 100% of the users who used the aluminum strip on their radiator end up having leaks of oil, at the place shown on the drawings by the red circles
    1_2017-11-27-3.jpg (You do not have access to download this file.)
    2_2017-11-27.jpg (You do not have access to download this file.)

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