Carbon monoxide

[tx_swordguy]

Hey guys , i have had one of the co cards and noticed it said sunlight can bleach the color dot. Therefore i bought a digital co detector. With the vents open i get zero co within the cabin area. That is at face level, in and around the floor and behind the dash as best as i can get while flying. If i put it behind me in the tail cone at arms reach i get as much as 30 ppm ( mostly 15-20). I have tried putting it along the sides of the seat and wing root area thinking it may be coming from there but nothing . Now if i close the vents and turn my eye ball wind screen vents ( which actually suck inside air out to stop incoming air) the co rises in the cockpit area to 20-30 ppm with the tail cone reaching 50 ppm. I know that 50 ppm is still OSHA 8 hr exposure limit but wonder what others may have found if they had tested in a similar fashion. Not sure where it would be coming in if not the fw or wing root/ spar bay. I have a single fuselage vent under the tail and was wondering if a second one either on the opposite side or on the bottom of the fuselage might be needed. Ideas and advice please.

[Panther16]

Likely coming in thru the Circular hole at the base of the vertical tail spar tail post Assembly. Try taping the hole closed with speed tape.
Keith Rhode
Sonex 214KE

[13brv3]

Have you noticed any increase with flaps down? I was fine with the flaps up, but down clearly was pushing exhaust back in through the holes for the flap pushrods. I was seeing numbers in the upper 80's just from base to the runway, and you could smell it. While researching CO readings, I kept seeing reports that it could be sucked back in around the tail openings, so it sounds like you're on the right track.
Rusty

[Bryan Cotton]

I have a digital monitor on the panel. You can see it in my pics and videos. I have yet to get over 0 ppm.

[tx_swordguy]

Thanks guys i will investigate the tail cone. I never got above 0 on the dash either but the closer to the tail cone i got the numbers increased. I will try sealing the tail more

[DCASonex]

There are two holes back on the tail cone if you have a conventional tail, the second one on the vertical post for the rudder, My CO2 went to near zero after plugging the two holes.

David A.

[tx_swordguy]

I tried plugging the two holes in the tail ( covered with gorilla tape). I then flew with all vents closed trying to get the co as high as possible. In the cabin the highest i saw was 18 ppm with most of the time fluctuations from 0-11. ( it looks like 10 is the lowest above 0 it will read.) sitting on a blanket in the baggage compartment about shoulder level and 2 ft behind my head highest reading was 34 with most in mid twenties. So it did help and cut my readings by 40% ish. I then put it in max reading hold setting and left it in the baggage compartment in the same place checking it every so often with it not getting above 31. I came in and landed with 2/3 flaps like normal and taxied to the fuel pumps. When i reached back to grab the monitor i was shocked that it maxed out at 148! Obviously the flaps cause a huge change in airflow and co infiltration. I think it must be coming in through the wing root since tail holes were taped up. What this taught me is obviously there is a huge difference in co concentration within the cockpit from the dash to the baggage compartment. I have also lost faith in those cheap co cards. I don’t suggest always flying with a high dollar co monitor but a $38 amazon monitor to give you an idea of what and where you have co is a wise investment.

[Bryan Cotton]

I have this one. I'm not sure it's any good.
https://www.amazon.com/gp/aw/d/B08TRKL94H

Any recommendations?

[tx_swordguy]

Don’t know if one digital is better than another . The one i bought is a hand held meter that has a yellow face and 4 buttons on it. Retails on amazon for $39. I cant figure out how to link it on my ipad. As long as it will show a reading of some kind it should at least give you an idea of the amount and where it is coming from. I have never had one of the cards go dark and then i saw that sun can bleach it. Also don’t know at what level it turns black. Those two items made me get the digital and started experimenting with where and how much co I actually had.

[13brv3]

I guess I got the high dollar one- https://www.amazon.com/gp/product/B076S6KBP2 I recall reading good reviews of it online, and it works well. My only complaint is that it doesn't automatically turn off, and it takes 2-3 min to calibrate on power up. During that time, it needs to be in clean air, so I just have to remember to turn it on before pulling the plane out of the hangar. I had a really old one that was long past it's "quit using after" date, but comparing the two showed that they gave nearly identical readings. I'd never rely on those spot detectors.
Rusty