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Good morning,

 

I have a new to me 912is (1300hr).  I am very familiar with Rotax engines as well, flown them for 300+ hours.

3 days ago, my Cyl 3 EGT temp was pushing yellow at 1750-1775. Did this during takeoff in the pattern, was the first time I've seen a yellow warning at 40hrs in this aircraft.  Decided to check plugs, even though they were checked/changed at transfer of ownership. A small amount of wear but nothing crazy, changed them anyway since i was checking.

2 days ago, still had some temp issues on 3 and now 4 started rising a bit.  A normal cruise 1 and 2 are typically 150-190 lower than 3 and 4 on the EGT's Coolant/Oil and CHT all well within normal range, no apparent power loss at all.

Yesterday first takeoff zero issues around the pattern. Second takeoff, EGT rises very quickly to 1800, flashes briefly and X's out, lane 1 light goes on.  Landed immediately and cycled lane1 and it reset.

In checking the distance from the exhaust exit, the probe is less than the desired 2.5-3 inches from the exhaust flange. I know the temps will be higher because of this so I take the 1750-1800 with a grain of salt, but they DID increase from the last 30 hours of flight for some reason so the placement shouldn't matter with apples over apples comparisons, just explains the high EGTS during normal operation, most posts say 1700 is the MAX you should ever see.. 

 

#1) When the EGT broke 1800 temp, is that like MAX number and caused the lane light to go on?

#2) I am fairly certain I could have reset the lane light in flight, would the light being solid indicate that lane actually went off because of the 1800+ temp?

#3) Does the fact my EGT's are slowly rising over flight time have any potential maintenance indicators with them?

#4) FADEC controls the engine.  When the FADEC reads an 1800 EGT did that cause it to 'turn off' Lane A to protect something?

#5) Am I creating my own stress by even worrying about EGT? Do they really serve a purpose as indicators?

I do have a new sensor coming.  I am doing an oil change today, not sure that will really do anything but, eh it needed it anyway so a good time. I am taking her in for a checkup with a new shop so I have a relationship with an AP/IA before 100hrs and annuals.

 

I appreciate any insight or experiences you have had and would share.

 

  • Re: 912is 1340hr new plugs

    by » 6 days ago


    I would believe it's the EGT probe. I've seen many bad ones. Usually easy to replace. If it were a real temp then other things would be abnormal too. I just replaced one last week.


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


  • Re: 912is 1340hr new plugs

    by » 5 days ago


    Thank you for the reply Roger. 

    if the problem continues to trip lane 1 off, is there a bypass so it doesn’t do that until I can get the sensor replaced?

     

    is it truly shutting off lane 1 and moving to lane two to operate the engine or is ithe light going on just to show a fault but it working other than the fault?

    Thanks again!


  • Re: 912is 1340hr new plugs

    by » 5 days ago


    Hi Dan,

    It could be a just a bad connection too. Like at the plastic plug or a wire has rubbed through on some metal or somewhere else.


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


  • Re: 912is 1340hr new plugs

    by » 5 days ago


    I did take a video of the issue, but the file is too big to post.  The previous owner suggested that a clogged/blocked fuel injector could be causing this and the temp is a real issue. 

    This AM i did a runup to 4500rpm.  Cyl4 was 250 higher than 3 which has always been my second highest, usually about 100-150 warmer than 1 and 2 since they get the most airflow.  at 4500 rpm cyl4 went from idle at 1500 up to 1825 and then lane A started flashing and it X'ed out cyl 4.  When I idled back and reset A, it dropped to 1580, tried one more time and did exactly the same thing.

     

    If this is a clogged injector probably best to have someone come look at it versus flying it.

    42497_2_IMG_5426.PNG (You do not have access to download this file.)

  • Re: 912is 1340hr new plugs

    by » 5 days ago


    Hi Dan,

    My 912 IS sport had an EGT #3 problem recently. Similar to your experience:

    1. EGT #3 increased slowly in the cruise until I eventually received the Red warning. 

    2. All engine parameters normal and engine running smoothly.

    3. Lane A red light started flashing and Red X displayed on EGT #3 - temp value removed. Other EGT values normal.

    The EGT # 3 probe was inspected and was clearly damaged. 

    Probe replaced and operating normally.

    Rgds,

    Glenn

     


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