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Hello all

I'm hoping someone might be able to help be diagnose some issues I have been experiencing with CHT and EGTs and I’ll explain what is happening. 

Firstly CHTs.  I’m having issues where during times when I’m slowing down, as in say, in the circuit and more often than not, on glide approach, the CHT on the right side (PAX) will climb into the red.  Once on the ground and taxiing, it will stabilise.  

I’ve swapped sensors and the problem remains.  Does not happen in the cruise or on climb. 

Secondly is the EGT.  Similar situation. I was yesterday slowing down to join midfield when my EGTs went into the red.  This time I decided to increase throttle and almost instantly they dropped back to normal.  Again, never happens in the cruise or on climb. 

The system is a Garmin touch system. 

I have checked cables and cleaned connectors and can’t get a solution. 

Not sure if it’s connected but occasionally my right side fuel tank will race up to full for a while.  

So you can see why this is driving me nuts.  

Anything you can offer would be of value.  

Cheers

John.  

  • Re: Some strange happenings with CHT and EGT

    by » 3 months ago


    John, I don't know the answer off the top of my head. What are the rpm indications when the anomaly occurs? Is this a 912UL, ULS or 914?

    Do you have an ammeter, if so, is the amperage dropping significantly?  How many hours on the engine? When it goes into the red, is it immediate with a throttle reduction? When you say you swapped sensors, put in new ones or exchanged locations? Are you measuring all 4  cylinders or just one per side of CHT's and EGTs? Once on the ground in taxi does it drop immediately as you noted with a throttle increase, or drift down into operating range? Any recent changes to engine, e.g. spark plugs? Air Filter, etc. Any power device turned off when you taxi after the spike? Not familiar with the Garmin, but if it includes a database have you taken a look at what it is telling you? Is the reading on an analog instrument or the EFIS?

    Jack

     


  • Re: Some strange happenings with CHT and EGT

    by » 3 months ago


    Charles J. Norris wrote:

    John, I don't know the answer off the top of my head. What are the rpm indications when the anomaly occurs? Is this a 912UL, ULS or 914?

    Do you have an ammeter, if so, is the amperage dropping significantly?  How many hours on the engine? When it goes into the red, is it immediate with a throttle reduction? When you say you swapped sensors, put in new ones or exchanged locations? Are you measuring all 4  cylinders or just one per side of CHT's and EGTs? Once on the ground in taxi does it drop immediately as you noted with a throttle increase, or drift down into operating range? Any recent changes to engine, e.g. spark plugs? Air Filter, etc. Any power device turned off when you taxi after the spike? Not familiar with the Garmin, but if it includes a database have you taken a look at what it is telling you? Is the reading on an analog instrument or the EFIS?

    Jack

    Hi Charles,

     

    This is a 912ULS. Running Garmin Glass - So all are info on the glass.

    The problem is I don't know how quickly it gets into the red, but quick enough that I don't know until I get an EMS warning.

    I swapped sensor locations, to see if the problem followed the sensor - but it did not.

    Yesterday it dropped the second I applied throttle. (The EGT that is) 

    Changes - yes had the 100, but it did it before and after the 100.

    No Analogue.

    Not sure if the Garmin logs it all.  Hmmmm.. Might look for that.


  • Re: Some strange happenings with CHT and EGT

    by » 3 months ago


    I've seen this with CHT's and EGT's before. Sounds like a poor ground. You have a ground just one that has become lose or deteriorated over time. Could even be a ground wire that the insulation has worn through. .  


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


  • Re: Some strange happenings with CHT and EGT

    by » 3 months ago


    Thanks Roger.


    I have checked all the wiring and it all looks good.  It's such a pain!  :(


  • Re: Some strange happenings with CHT and EGT

    by » 3 months ago


    Wires may look good, but can have a poor connection from something being lose or corrosion you may not see. All wires and connections should be considered hand tight, but wrench lose. Put a screwdriver or wrench on all connections.

    You have a ground, but maybe a poor one. This has happened to me many times and now it's the first thing I check.


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


    Thank you said by: John Fleming

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