I have a 1968 Cherokee 180D
I have been using a calibrated CO monitor for the last 6 months. It has provided some interesting results.
The good news it never indicates any CO (0 ppm) during runup, so exhaust system seems to be good.
However, it started showing some significant CO during some landings, and an occasional takeoff.
Some of the more repeatable CO indications are:
Slow flight with wind off the right (including crosswind landings with wind from the right)
Soft field takeoff (Full throttle, slow speed, nose high)
Sometimes the indications can get as high as 40 ppm temporarily, and are usually less than 20.
My best guess is that the combination of nose high and prop wash (and wind from the right) places the exhaust fumes right at the left wing fresh air inlet. When I close the left vent (I can still feel some air though) it still occurs but not as high an indication. When I open the passenger side vent with the others closed in an attempt to flush the cabin with clean air, so far no indications (0 ppm).
Just curious if anyone has had anything like this
Thanks!
