I have a small plane and there is CO leaking into the cabin. I have a CO monitor and I can keep the level down to zero. Unfortunately, to do this I have to keep the two small portals in the side windows open. In the Summer this is not too bad but, in the Winter, I get very cold and uncomfortable. For the last two years during my annual conditional inspections the aircraft mechanics have looked for and corrected any exhaust leaks they could find, or thought were suspect. Sadly, the problem persists, and temperatures are dropping.
My question: is there anything (preferably an aerosol spray) that can make this invisible gas visible?