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Thread: 25hr Inspection of 912is - concerns

  1. #1
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    Default 25hr Inspection of 912is - concerns

    I started my 25hr inspection on my 912is with an oil change. I did not have a differential pressure tester available at the time. After a short warm up I removed the bottom plug from the oil reservoir and emptied it. The oil was dark but appeared normal and there was nothing visible in it. I saved it in case I want to get it tested.

    I removed the magnetic oil plug for inspection. There were some deposits (see image), more than none, but not a lot. All appeared small in size and nothing was sharp after rubbing between fingers. However, Iím not sure if this looks like more than I should expect for the first 25 hours.

    Lastly, I removed the oil filter. This thing was way too tight. I believe this was from the factory though. I replaced it and tightened it as per manual. I then opened up the old filter. As many times as Iíve changed my car filter Iíve never once opened it. It was interesting. After cutting out the paper filter and letting the oil drip off (left it about an hour) - there were no large deposits of any kind. Running a magnet over it didnít pick up anything. However, using a flashlight I did see about 10-20 sparkle/glitter sized flakes on the shop towel and embedded in the paper. Is this expected or of a concern? (see images)

    After replacing 3 L of oil as per manual I rotated the prop 20+ (about 40) times as I was expecting a burp - but I never got one. Is that expected? Oil level on the dip still remained just about at the minimum.

    I removed all the spark plugs. I believe they look ok. Consulting google I donít see anything of major concern. Would you think differently? (See Images) I replaced all plugs with a NKGs gapped to 0.032-0.033 in.

    The differential leak test on the 912is took place after my oil change due to not having it available. Starting with cylinder 3 I found TDC using a rubber glove on the end of the connected hose. I slowly increased the pressure to 80psi and it was holding at 78psi. However, I noticed I was getting a gurgling/burping sound in the oil. This seemed very strange. I repeated on the remaining cylinders and noticed the oil gurgling starting anywhere from 10-40psi, although there was no pressure change detected on the differential. My oil reservoir was now nearly flowing over. Whatís going on here? Is this expected? I wouldnít think so. (see video)

    During the 25hr (ecu indicated, 28hr timed from engine start) I only used about ĺ litre of oil. There were no other concerns during flight that would cause suspicion. (ie loss of power, sounding different etc).

    During visual inspection everything else was ok except for a very small coolant drip (already known) at the connection to the radiator. Additionally it was found that this same hose was rubbing/touching the cylinder fins and had started to melt away the protective sheath in that area. This was fixed by shortening the hose to allow a better (straight fit) onto the radiator connection. This provided a gap at the fins as well as improved the fit which should remedy the small drip. Additionally it was required to shorten the heater core attachment on the T junction of this hose to prevent additional pressure pushing the hose back towards the fins. (See images).

    All other inspection points had no issues.




    https://res.cloudinary.com/tracstarr...ressureOil.mp4
    https://res.cloudinary.com/tracstarr...SparkPlugs.mp4


    Oil Magnetic Plug
    https://res.cloudinary.com/tracstarr...121_134047.mp4

    https://res.cloudinary.com/tracstarr...121_134038.jpg

    https://res.cloudinary.com/tracstarr...121_134042.jpg

    https://res.cloudinary.com/tracstarr...121_134204.jpg

    https://res.cloudinary.com/tracstarr...121_134045.jpg

    https://res.cloudinary.com/tracstarr...121_134036.jpg



    This is after oil change and rotation of prop by hand
    https://res.cloudinary.com/tracstarr...128_105129.jpg

    https://res.cloudinary.com/tracstarr...128_105131.jpg



    Oil filter tear down
    https://res.cloudinary.com/tracstarr...128_094408.jpg

    https://res.cloudinary.com/tracstarr...128_094329.jpg

    https://res.cloudinary.com/tracstarr...128_094521.jpg

    https://res.cloudinary.com/tracstarr...128_094420.jpg

    https://res.cloudinary.com/tracstarr...128_094445.jpg

    https://res.cloudinary.com/tracstarr...128_094341.jpg





    --Keith
    Almost Flying Model 6
    912 IS
    Airmaster Prop
    Garmin Stack
    C-FKLO

  2. #2
    Senior Member efwd's Avatar
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    Default Re: 25hr Inspection of 912is - concerns

    Hi Keith
    The soft iron "fuzz" on the magnetic is what I find on my 100hr inspections. Slivers would concern me. It doesn't sound as though you have that. I use alcohol to rinse the oil from the fuzz. The qty of fuzz is something less than what it appears once you remove the oil. I still aim to run the findings by my Engine guy at California Power Systems so don't rest on what I say.
    As for not getting the burp. You absolutely should be achieving the burp. The engine must be in operational mode. All holes plugged up so as you rotate the prop the internal pressures inside the engine are able to build. That pressure is what pushes the oil back into the reservoir. You will need to verify all your valve tappets are within the required parameters. If you have gotten air in the oil system and your tappets are not correct then this may likely be why you are getting blow by when you do the differential pressure check.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  3. #3
    Senior Member 109JB's Avatar
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    Default Re: 25hr Inspection of 912is - concerns

    As far as saving the oil in case you want to do an analysis.....Just do it. It is about $30-40 and is cheap insurance/assurance.

  4. #4
    Senior Member JoeRuscito's Avatar
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    Default Re: 25hr Inspection of 912is - concerns

    Everything you describe sounds fine to me. I have a 912 is as well. I also get gurgling in the oil Tank when doing the leak down test. Although my oil tank will never overflow, even after a fresh 3l oil change.

    Keep spinning the prop and Iím sure it will
    Burp, assuming all the holes are plugged as stated above. They burp faster when warm.

  5. #5

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    Default Re: 25hr Inspection of 912is - concerns

    Sounds like you may be spinning the prop too fast during your "burping" process. When burping, bring the prop blade to the point of maximum internal pressure/compression and pause at that point for 2 -3 seconds to let the cylinder pressure subside and thus pressurize the crankcase. Then rotate the prop on to the next compression point and repeat. My 912ULS typically requires between 10 - 20 blades to burp depending on the temperature of the oil and how long the engine has been sitting. Do not rotate the prop backwards as this may cause undesired air to be introduced into the oil lines.

  6. #6
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    Default Re: 25hr Inspection of 912is - concerns

    Thanks everyone. Turns out I totally forgot about installing the plugs again when trying to burp... so that explains that. Also glad to hear other things are normal and expected. Also got similar responses from rotax-owners group.
    Almost Flying Model 6
    912 IS
    Airmaster Prop
    Garmin Stack
    C-FKLO

  7. #7
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    Default Re: 25hr Inspection of 912is - concerns

    So as usual it's taking forever to get things done. I replaced my fuel filter, cleaned out the coarse fuel filter (had a few small pieces in it). Also replaced a fuel return line that had a slow drip between the header tank and the fuel sensor tank.

    Tonight I was able to do an engine start to make sure things are all good. No fuel leaks, oil pressure came up right away so far so good. However, when I did my RPM drop lane checks lane A was fine, almost no drop, but when switching off lane B there was a drop of 350rpms followed by a quick jump back up to about 170 rpm difference. This behavior is outside of expected and totally different from what I'm use to. Additionally, when switching back on the lane (in either case) the RPM would settle about 100RPM higher than when the lane was switched off.

    I didn't have time to check anything, but suspecting maybe the new spark plug gaps? Although gapped within spec and tested with a feeler gage. Anyone have additional things that I should check? Might be a day or two before I get back out there. Want to get things wrapped up as next I have to pull my prop blades for inspection.
    Almost Flying Model 6
    912 IS
    Airmaster Prop
    Garmin Stack
    C-FKLO

  8. #8
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    Default Re: 25hr Inspection of 912is - concerns

    Sorry to sound negative but I would be extremely concerned at the amount of metal on your magnetic plug. I have a 912ul in my model 4 that now has about 255 hours. I change my oil every 50 hours. I just changed it a few weeks ago at 250 hours and the magnetic plug had nothing on it. Absolutely nothing. The 1st oil change when the engine was new had only a tiny "slug" but nothing that could be felt. I've never seen as much as a speck in my oil filter. I can't believe it's normal to see that much metal. There are lots of people that know more than me and I hope I'm wrong. But I would sure be asking someone who is an expert. I hope for the best for you. James Thomas

  9. #9
    Senior Member rv9ralph's Avatar
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    Default Re: 25hr Inspection of 912is - concerns

    Check that all of your plug caps are fully seated, you might have a loose one.

    Ralph

  10. #10
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    Default Re: 25hr Inspection of 912is - concerns

    Quote Originally Posted by jrthomas View Post
    Sorry to sound negative but I would be extremely concerned at the amount of metal on your magnetic plug. I have a 912ul in my model 4 that now has about 255 hours. I change my oil every 50 hours. I just changed it a few weeks ago at 250 hours and the magnetic plug had nothing on it. Absolutely nothing. The 1st oil change when the engine was new had only a tiny "slug" but nothing that could be felt. I've never seen as much as a speck in my oil filter. I can't believe it's normal to see that much metal. There are lots of people that know more than me and I hope I'm wrong. But I would sure be asking someone who is an expert. I hope for the best for you. James Thomas
    I appreciate the concern. It didn't fall by the wayside with me either. I've confirmed with multiple Rotax Heavy Maintenance Certified Mechanics and they have no issues with what's there for the first 25hr.
    Almost Flying Model 6
    912 IS
    Airmaster Prop
    Garmin Stack
    C-FKLO

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