Hi Ben.

I have noted a number of replies saying yes and no to your question.
Unfortunately I cannot comment with authority on the 172's system, but on
CT-4s small pinprick size holes in both the heated and cool air scatting
were normally found to be the cause of higher than allowable levels of
carbon monoxide in the cockpit on post maintenance ground runs.

I tend to be wary with these matters. You can't just pull over to the side
of the road for some fresh air if you start feeling tired. :-)

Darryl Gibbs.


"Ben Jackson" wrote in message
et...
I found the SCAT tube between the muffler shroud and the defrost vent
in the glareshield has some cracks (you can only see them if you flex
the tube a certain way, which is why they've been missed).

Does this present a carbon monoxide danger? It's not the heat exchanger
that's cracked, only the tube that carries the warm air to the cabin.
I plan to get it replaced soon but I need to know if I should ground the
plane in the meantime.

--
Ben Jackson

http://www.ben.com/