Lancair Live!

Eddie Addison reports this with his ES…

I have the Garmin 900GX Platform, a couple of weeks ago my EGT and CHT’s began showing erratic readings. See-sawing from normal to below zero and occasionally getting Red X’s across the page. My Avionics shop replaced the Garmin Module but the oscillating readings continued. He observed that when the cross feed and Number 1 alternator was off everything returned to normal.
He determined that the alternator may be bad…we replaced the alternator but this did not remedy the issue.
I am sure that this is not the first occurrence in the fleet. Can you post this to see if anyone has experienced a similar or like situation and the cure?
Thanks!!!!

Regards,

Eddie


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Man that sucks with the Engine temp indications doing that. I will tell you that Garmin equipment is very sensitive to improper or loose grounds. From your description of all the engine temp indications I would start with a bad ground somewhere…. Garmin not only grounds the equipment to typical grounding blocks but also there are grounds from the individual wire bundles to the back shell connectors on both ends of each connector. I would look for a loose ground or a broken ground wire. Pull and inspect all connectors to the Garmin engine indication system, (not sure for the G900 system), but I am sure it’s a GEA box of some sort. You will see this box as all the EGT/CHT probe wires will go to it. From there the signals are sent into the G900 displays and that is usually another significant connector. These grounds are generally a small 22 gauge wire to a round closed terminal end with a small #4 screw to the end of the back shell connector.

Another less known fact is that some inexperienced installers install the little bar (strain relief) that rests and secures the bundle from pulling on the pins in the connectors are installed upside down with the sharp edges laying across the wires. This leads to the little bar cutting into the bundle and wreaking havoc.

I will post all of this on LancairLive.

George


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