"Andrew Gideon" wrote in message
online.com...
Our Cessna R182 is getting CO in the cockpit.

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

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

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

I ask these questions because I suspect *all* GA aircraft have at least some
CO in their cockpits.

I bought one of the CO Experts digital CO monitors about a year ago, and
some of what it seems to be saying surprised me.

At least in my plane (an old C-150 with typically drafty windows) the more I
open up the vents (and to some extent, the windows), the more CO seems to be
present in the cockpit - which was exactly the opposite of what I expected.
If I close everything up tight (or as snug and things get), the CO meter
shows a low level (although it does vary a bit depending of power settings,
climb/descent/cruise, and even which way the plane is turning; it also
varies significantly depending on where in the cabin it is).

I've come to the following tentative conclusions:

1. There's always at least a little CO in the plane if the engine is
running; the unit it quite sensative.
2. I'm not getting a significant amount of CO through the firewall or
aircraft structure.
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.
4. Under most configurations, the CO level is nice and low. The worst
configuration seems to be full power, in a climbing right turn (to my
surprise, the turn direction made a significant difference) with all the
vents open - under that config the CO level climbs somewhat, but I rarely
fly in that configuration for extended periods.
5. Experimenting with the CO monitor in different locations throughout the
cabin produced more surprises: the further forward I placed the monitor, the
lower the CO levels were. I expected the highest readings would be at knee
level or foot level, close to the firewall. Nope. That's where the lowest
levels were. The highest levels were behind the seats, just aft of the
window frames (where I suspect most of the CO is coming in). I considered
this good news since the levels near my head - where the air I'm breathing
is - were among the lowest.

I'm sure it's different for every airplane, but at least in mine, the
results were surprising but ultimately reassuring. Now I leave the CO
monitor on the "hat shelf" behind the baggage area behind the seats, about
24-30 inches behind my shoulders. It chirps regularly in flight (indicating
a low level of CO). Nice to have, for a hundred bucks it provides a lot of
peace of mind: I do *not* worry at all about CO killing me (lots of other
things still to worry about, but I get to cross CO of my list, as long as I
hear that periodic chirp from the CO monitor from behind the seats). How
many other worries can you pretty much completely eliminate for a hundred
bucks?

Hope that helps a bit.


David Herman
N6170T 1965 Cessna 150E
Boeing Field (BFI), Seattle, WA
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