High Carbon Monoxide readings

[chrisk]

A few years ago I purchased a CO detector.   Its typically had low reading, 10 or less.   Recently I have gotten slightly higher readings with full rich operations.   I took a look at the rudder boots and found one ripped.   Would this cause higher CO readings?   And is this a difficult fix?  I assume a new boot is what is needed.  Where does one find a new boot?

[ArtVandelay]

Easy enough to test, put your detector down in footwell, it should read a higher amount.

[chrisk]

16 minutes ago, teejayevans said:

Easy enough to test, put your detector down in footwell, it should read a higher amount.

That thought only occurred to me after I made it home.    I'll do that the next time I am out at the airport.

[Danb]

Try laser for the boot

[mooniac15u]

Lasar

[takair]

Depending on how high the readings are, consider having you exhaust inspected.  Lots of discussion on this in other threads.  You could have a crack starting.  When was the exhaust last inspected?

[FloridaMan]

I think I'm getting some in around the door seal at high AoA in the climb. Turning on the heat or opening vents clears it out. 

[DanM20C]

17 hours ago, chrisk said:

A few years ago I purchased a CO detector.   Its typically had low reading, 10 or less.   Recently I have gotten slightly higher readings with full rich operations.   I took a look at the rudder boots and found one ripped.   Would this cause higher CO readings? 

You can certainly have CO coming in through the torn rudder boots, @Bob_Belville found a small leak in this area in the past.

How high are your readings?  I would think that during normal operation(flying) you should have very minimal CO under the cowl unless there is a leak someplace.  With a turbo any exhaust leak should be investigated closely. 

Keeps us posted to what you find.

Cheers,

Dan

[Andy95W]

Last year my CO was usually around 4-5 in flight.  

This past summer, I installed a new interior, re-taped the floor, fabricated new rudder boots that actually fit tight, and redid the seals in the nose wheel well.  My CO now reads 2 and doesn't seem to change.  On the ground, it is less than 10.

I didnt think the work would affect the CO until I read this thread and noticed the difference myself.

[Yetti]

could come in around all that loose duct tape.   replace with aluminum tape.  duct tape can hold water.

[chrisk]

I pulled to lower cowling and took a quick look at the exhaust.  Everything looks good there.  No signs of any leakage.   To see if it is the rudder pedal boots, I taped them to close the holes.   I'll have to take another flight to see if anything changes.

As for the readings, I was seeing 45ppm when full rich and in the landing configuration.  During cruise and operating lean, I see 0ppm.   Oh, and the heat is off (and has been for  at  least 6 months), so I'm sure it is not coming from the heater.

 

[bradp]

FWIW was entraining a bunch of CO from the window and door when open during summer taxiing. Check door seals as well. 

 

[ijs12fly]

On 11/24/2018 at 12:50 PM, chrisk said:

I pulled to lower cowling and took a quick look at the exhaust.  Everything looks good there.  No signs of any leakage.   To see if it is the rudder pedal boots, I taped them to close the holes.   I'll have to take another flight to see if anything changes.

As for the readings, I was seeing 45ppm when full rich and in the landing configuration.  During cruise and operating lean, I see 0ppm.   Oh, and the heat is off (and has been for  at  least 6 months), so I'm sure it is not coming from the heater.

 

@chrisk Did you ever figure out what was causing your CO issue?   I am chasing a CO issue as well at high power level and during climb.  

[ijs12fly]

On 11/23/2018 at 1:11 PM, Andy95W said:

Last year my CO was usually around 4-5 in flight.  

This past summer, I installed a new interior, re-taped the floor, fabricated new rudder boots that actually fit tight, and redid the seals in the nose wheel well.  My CO now reads 2 and doesn't seem to change.  On the ground, it is less than 10.

I didnt think the work would affect the CO until I read this thread and noticed the difference myself.

@Andy95W Andy,   how did you fabricate the new rudder boots?   When you redid the seal in nose wheel weil what seals do you mean?  I have been chasing a CO issue for some time and looking to try all options.  

[Andy95W]

I used the old boots as a template, but the old ones had a huge hole for the pedal shaft.  It needs the big hole to get it to fit around the rudder pedal horizontal pieces.  So when I made the new ones, I designed in a Velcro seam so that the new ones wrap around the vertical shaft, Velcro together, and then get screwed to the floor and firewall.

I made the new boots from black IZIT Leather, made by Willow Tex.  I had some that was burn certified from a previous project.  Once installed, I used black ty-wraps at the top to really seal them well around the pedal shafts.

[Raymond J1]

Les bottes sont faciles à refabriquer (simili cuir classe M1), il faut s'occuper du collage sur les flasques et du laçage sur les tubes de gouvernail comme il est dit précédemment. Côté plancher, il y a un orifice à droite de la boîte de train avant (photo 3), utile pour le passage de la commande de roue avant. Avec la garniture murale, ce trou n'est pas visible, mais cela implique que la plaque de fermeture entre la boîte de vitesses et le carénage inférieur est montée de près avec le plus grand soin. En montée, volets de capot ouverts, sur les modèles à tuyau d'échappement court, un passage de CO peut être réalisé par cet orifice.

Juste un constat sur mon 67 F.

 

Edited May 14, 2021 by Raymond J
picture change

[ijs12fly]

@Raymond J Thanks for sharing the pic's.  Nice work.  The only issue I see is if CO is coming from the panel below, the holes in these boots will not restrict flow of CO into the cabin.

 

 

[Raymond J1]

45 minutes ago, ijs12fly said:

@Raymond J Thanks for sharing the pic's.  Nice work.  The only issue I see is if CO is coming from the panel below, the holes in these boots will not restrict flow of CO into the cabin.

 

 

This is absolutely correct, one should not rely on the internal seals of the cockpit and be very careful, on the right side of the aircraft (exhaust pipe environment) to the perfect assembly of the external panels and their tightness. To a lesser extent, it is also necessary to take care of the sealing of the windshield bay sheets on the old Mooney, and do not forget the gummed canvas that makes the water seal at the same time as sheet metal gasket. In another subject, there is talk of a paste that Mooney used to plug the gaps. This product is called with us "BT sealant (Low voltage)", it is butyl sealant and it is originally a sealant for sealing spot welding joints in the automotive industry, it is gray or black in color. This seal is used by Mooney on the firewall but also for the installation of glazing.

[Davidv]

The door seal can often be the culprit for CO.  Your exhaust travels down the belly of the plane and in some models right by a flap faring that has a tiny opening to the cabin.  When you have a bad door seal it creates a pressure vaccum and sucks this exhaust either through the flap faring or some other non-sealed area below the plane.  You might notice it more in climb.  If your put a piece of paper around your door seal and it sticks to it in flight this is most likely at least part of your problem. 

[larryb]

I had a missing cam lock on the belly pan just aft of the exhaust pipe that caused the CO to be noticeably higher.

[Buckeyechuck]

Just purchased set of rudder, Johnson bar, gear and aileron boots from aero comfort. Look good, haven’t installed yet. Airplane goes in for annual later this week.