David Herman wrote:

How do you know - what sort of gizmo are you using to test (some are quite
accurate, others ain't)?

I forget the make/model, but I'll get that when I'm next at the airport.

How much CO are you getting? Is it more than other airplanes? Is it
enough to worry about?

Our club has four aircraft: a straight-leg 182 and two (180HP modified) 172s
(an N and a P). Swapping detectors around yields zero consistently in the
other aircraft, and nonzero readings in the R182. I don't recall the
numbers, but there were not in the "you're about to die" range but they
were in the "you should do something" range (judging from the documentation
of the detector {8^).

Where within the cabin are you taking your readings? Are you taking
readings at different locations in the cabin, and under different flight
configurations?

All over, yes, and yes. I myself flew one of the "stick the detector
somewhere to see what happens" flights. We've been unable to discern a
pattern, although there does appear to be a slight increase in the
passenger seats vs. the front seats. Maybe. I've always assigned this to
the fact that the air vents are in front, and the difference is slight
anyway.

[...]
3. Most, if not all, the CO in the cockpit seems to be coming in from
outside, probably mostly leaking in around the windows, and coming in
through the cessna soup-can vents at the wing roots.

When I open those vents, the numbers appear to go down.

[...]

Hope that helps a bit.

I'm sorry, but - at least with our detectors - the fact that the other
aircraft show zero does imply an issue here. We may have less sensitive
detectors than you.

- Andrew