By Bob Dilk CFI, CFII
Good procedures keep us safe.
I am an independent CFI and most of my instruction is given in the local rental fleet. Last year I purchased and started wearing a carbon monoxide (CO) monitor whenever I am wearing a jacket (cold weather) or when I fly in a customer’s aircraft.
Last week I was doing a flight review in a customer’s aircraft, and out of habit I hooked on my CO monitor. During the take off roll, this beeping is heard in the cockpit and I call, “abort, abort, abort.” After exiting the runway, I looked at the beeping CO monitor and commented to the pilot we have a CO leak.
I opened the door and used fresh air to clear the alarm. The customer was not yet convinced he had an issue since the alarm was quiet during the taxi, so we tried another takeoff. As we approached rotation speed, the alarm went off and we aborted this takeoff.
Carbon monoxide in an aircraft usually comes from a leak in the exhaust system where the cabin heater muffler covers the exhaust. These leaks can be difficult to detect unless you suspect a leak and disassemble and inspect the heater muffler. Many small leaks go undetected until something bad happens.
CO is a colourless and odourless gas that can, at very low concentration, make you sick, confused, unconscious, or kill you. I encourage you to research this subject and determine if purchasing a CO monitor is right for you.
Interesting sidebar: I had a customer relate to me that last five people he took for rides got queasy or airsick in his airplane. He wanted to see if his flying style was causing the issue. During our flight together I noticed the CO monitor was indicating 15 to 20 ppm CO. Not enough to cause an alarm but may at this level exacerbate the air sickness issue with his passengers,
He is investigating this CO leak with his A&P. I am curious how this will play out.
Safe flying.