High CO readings in cockpit...

[mooneym20d]

I just bought a digital CO detector because I suspected CO in the cockpit. I confirmed my suspicions when I turned it on. The readings were as follows:

     Taxi - heat on - cowl flaps closed - 347 ppm

     Taxi - heat on - cowl flaps open - 39 ppm

     Taxi - heat off - cowl flaps open - 22 ppm

     Cruise - heat on - cowl flaps closed - 38 ppm

     Cruise - heat off - cowl flaps closed - 16 ppm

     Approach - heat off - cowl flaps closed - 44 ppm

From these readings, I deduced that a leak was occuring somewhere outside the heat shroud and coming in through the firewall. It seems the slower the air flow in the cowl, the more CO I detected. I checked the exhaust and found the tailpipe clamp had come loose. That was tightened and the remainder of the exhaust was checked. The heat shroud was removed and no cracks were found. New gaskets were installed at the flanges and the nuts were torqued to specs.

The plane was put back together and another CO check was conducted. I no longer get the 347 PPM reading, however, I do get as high as 38 PPM on the ground and 18 PPM on approach. Cruise gives me approximately 8 PPM.

Can anyone give me any insight as to wether these readings are normal? I do know that these levels are not dangerous for the duration of exposure.

I will be taping any gaps between the nose gear well and firewall that lead to the cabin. 

 

 

[jetdriven]

Also look at the boots that go under the rudder pedals.

[Mooneymite]

I, too sometimes get a 30-35 reading during taxi, but nothing in-flight.  i figured it had to do with weird airflow patterns associated with ground ops.  My cabin is hardly "airtight", so maybe the exhaust gases just swirl into any gap in the door seal, whereas, in flight, the airstream carries the exhaust down and away from the cabin door?

Such low readings for such a limited time are probably not too dangerous as long as they stay low and occur only during ground ops.

[Magnum]

I had readings up to 50ppm while taxiing, too, and resealed every gap at the firewall. Now it is ok.

[kerry]

I had a strong exhaust smell while my landing gear was extended. On this forum Jose said the tail pipe needs to be turned out. If not it causes a vacuum effect thru the nose gear bay. I turned mine out and its better. I notice a lot of mooney's on the ramp with tail pipes going straight back and not turned out.