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Some of you may recall This Thread from last spring.

While it may appear that it the thread suddenly went Quiet, much has happened in the interim.
John, Alex and I have been working on a solution to the problem.

We have found that the underlying problem is that the Oil Pressure Regulator Valve is prone to fluttering in the oil stream in some engine installations.
While the Rotax design looks quite reasonable, once the Valve Opens and moves away from the Valve seat, there is no longer anything stabilizing its position. It is free to become a "Bobble Head" if it wishes.



This is evidenced by the wear marks on the side of the stem of the Mushroom Style Valve.



After more than a dozen design changes and over 60 hours of in-flight testing, we think we have an elegant solution.
The new valve is a simple drop-in replacement for the current valve and requires minimal effort to replace.
The end result is Rock-Steady Oil Pressures that varies very little over wide RPM and Temperature ranges.

What we are looking for at this time is one or two Candidates that would be willing to Beta-Test the New Valve in their 912ULS Powered Aircraft.
If you find the Valve beneficial, you will be welcome to keep the Valve for your personal use as compensation for your efforts.

If anyone has a 912USL Engine that shows the Oil Pressure Varying Rapidly in excess of 10 PSI (or Much More!) once at operating temperatures,

Please contact me at ... WHertzel1@Yahoo.com
BobbleHead_2018-01-18.jpg (You do not have access to download this file.)
MushroomDamage_2018-01-18.jpg (You do not have access to download this file.)

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Bill.Hertzel@Yahoo.com
Clicking the "Thank You" is Always Appreciated.

  • Re: Erratic Oil Pressure 912ULS

    by » 3 years ago


    This e-mail is not woking

  • Re: Erratic Oil Pressure 912ULS

    by » 3 years ago


    That e-mail has been working for more than 20 years.

    Try again, or post your Email Address in the 'About You' Tab of your profile.
    Or just post it here and I will contact you.

    Bill.

    Edit: I just noticed your GMAIL message came through. Never Mind! :)

    Bill Hertzel
    Rotax 912is
    North Ridgeville, OH, USA
    Bill.Hertzel@Yahoo.com
    Clicking the "Thank You" is Always Appreciated.


  • Re: Erratic Oil Pressure 912ULS

    by » 2 years ago


    This thread is 6 months old now. What was the outcome please of your new solution ?, I have been experiencing the same issues as original. Once the oil heated up I had massive bouncing at full rpm and low rpm. I got a new spring and the new mushroom head valve piston and fitted it yesterday. While the oil temp was under 40deg C the oil pressure was rock solid. Once the oil reached about 45 deg then the pressure started bouncing again at lower rpm but seemed to be solid at higher rpm. I found it bounced up to 2300 rpm then after this it was quite stable. I should have I have not done anything with the hoses or oil tank just replacing the valve piston and spring made this change so it seems to show this is where the issue is. I had a Honeywell sender fail and I have it on a MGL RDAC I replaced this with a standard VDO style resistive sensor and also remote mounted it and it seemed to work fine for a while but then I started having this bouncing issue and it just kept getting worse.

  • Re: Erratic Oil Pressure 912ULS

    by » 2 years ago


    Same problem here. Apparently the oil pressure fluctuating is factory normal. The reason are faster sensors and displays that reveal the fluctuations not shown with resistive sensors. You may find some info here:

    http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1526903809

  • Re: Erratic Oil Pressure 912ULS

    by » 2 years ago


    I changed my honeywell sensor out and fitted a old resistive VDO sensor I also then hooked up a analogue VDO gauge to the sensor and thats how I confirmed it was not the RDAC in my MGL doing it. I also put another resistive sensor on to confirm. So mine is definaetly a oil pressure relief problem. Its exactly like the threads here

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