CO level?

[FredFenster]

So I bought an electric carbon monoxide detector with a digital display on it. I know I've got an issue in my airplane (saw and smelled exhaust this weekend through the heat vents, pretty obvious!) but it got me wondering is there an acceptable level above 0? I saw 13-16ppm during taxi and run up with the heat off. Searching online, levels above 35ppm are bad for prolonged periods. If you have a CO detector, what kind of readings are you getting in flight?

 

[flyingron]

The Navion with the canopy open and no wind can get some pretty high CO levels into the cockpit. With the lid closed or with motion (or wind) it seems to not waft in.

 

[Capt. Geoffrey Thorpe]

Ooch that red knob out just a bit...

 

[BigBadLou]

... it got me wondering is there an acceptable level above 0?

No.

If you CO detector shows any levels, that means CO is getting into the cabin and that should not happen, period.
Yes, there are exceptions of doors open while taxiing with the wrong angle of wind and you can blow some CO into the cabin that way, for example.
But with the cabin closed, CO should never be present. For that matter, CO should never be present under the cowling either. All CO should exit via the exhaust under the belly and be blown away by propwash.
Did your mechanic do a good leak check on the exhaust during last annual?

FWIW, my CO detector reads 0 during taxi and in flight. With heat on and off.

 

[RV10flyer]

In-flight, I want to see 0 ppm, just like in my HVAC client's homes. As others mentioned, you might see some low numbers during runup and taxi, depending on winds and other nearby aircraft. Try driving on I-75/85 rush hour traffic in Atlanta with the CO detector. I put it away. No wonder that traffic was so tiring.

 

[FredFenster]

Did your mechanic do a good leak check on the exhaust during last annual?

I've only had the plane since October, so I haven't had it through an annual yet. It wasn't checked for leaks before buying though. Exhaust was pretty new (2 or 3 years old, less than 100 hours) so attention wasn't put on that.

 

[Gmonnig]

I could be wrong but I'm pretty sure CO levels below 40ppm are the requirement for FAA certification. Retracting gear, cowl flaps and how well sealed the fuselage is can effect the rating. Running lean in cruise helps a lot but I was suspecting slight leaks so I bought a digital detector. Works great! I did find a very slight leak during the annual so I'm curious to go flying tomorrow to cross check the numbers. I only had CO during run up and then when I lowered the gear in the pattern.