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- Nov 17, 2018
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I posted earlier here about my problems with CO readings in the cabin during flight after just completing an engine overhaul. I have a digital CO Guardian monitor installed in the panel. It reads CO Reading Normal until the level reaches 10 ppm, then displays the current reading on LCD display. It is model Aero 551. When the cabin is completely closed it will start displaying a reading in about 3 minutes. If you crack a vent, or crack on the heater or defroster it clears the reading right back to normal. We put on new mufflers and of course new exhaust gaskets. I have had this monitor in the panel for about 7 years, and they are supposed to be renewed every 5 to 7 years, so I thought maybe that was the problem. So I exchanged my unit for a new one. Same results. So, I thought who knows, maybe two bad ones? So I bought a CO Experts potable monitor that displays 0 until the CO level reaches 7 ppm, then begins to alarm at 10 ppm. It consistently reads a little lower than the CO Guardian. In flight the levels on it will reach about 12 to 17 ppm while the CO Guardian will reach 15 to 26 ppm. Again, the inclusion of any fresh air at all will immediately clear the displays to 0. I honestly can not remember seeing this prior to the overhaul, but very often either the heater is on, or a vent is open. So my question here is two part. Does anyone have any other ideas of what might be causing this, and secondly for those of you with digital CO monitors if you have the cabin closed with no fresh air source, what do your monitors read? Thanks!
