CO is odorless and it's effects are insidious - it'll get you before you
know what's srong. So "can't smell anything" isn't too reassuring regarding
CO intrusion in the cockhouse.

If you haven't installed a CO warning device in your airplane, you should
without delay! They range from simple passive devices that turn color when
CO is present to electronic sensors. Some are undoubtedly better than
others, but any is way better than none!

Dan Schaefer