CO mystery - any ideas?

On Sat, 06 Nov 2004 20:05:19 -0500, Andrew Gideon wrote:

Our Cessna R182 is getting CO in the cockpit. We've now had three different
shops look at it multiple times, all to no (complete) effect. They've done
things like resealing the firewall, the gear-wells, the exhaust, and the
like. But still we get CO.

We've swapped CO detectors around between planes, so the detectors' results
are trusted.

One interesting oddity: turning cabin heat on does seem to get rid of the
CO.

It slightly pressurizes the cockpit, hence the cockpit is less likely to pull in
exhaust gasses.

I've heard that Cessnas often pull the CO in *from the tail*. The cockpit,
being normally a low-pressure area, sucks the CO from the tail to the cabin.
I'd take a look at holes in the fuselage aft of the cabin. If there aren't any
obvious gaps, seal the inspection panels, etc. with tape and see if the amount
changes.

Ron Wanttaja