231 Carbon Monoxide Problem

[tomatl]

You were right: a mechanic in Princeton removed the panel and replaced a couple of locknuts and the missing screws. Now CO is mostly back to zero in cruise.


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[carusoam]

14 hours ago, tomatl said:

You were right: a mechanic in Princeton removed the panel and replaced a couple of locknuts and the missing screws. Now CO is mostly back to zero in cruise.


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39N/Princeton?

Those guys are really getting to know Mooneys... 

Best regards,

-a-

[tomatl]

Yes, 39N. I flew to Princeton for a business meeting, my first time at the airport. They had a couple of Mooneys in their shop and also one for sale. The mechanic was really nice and knowledgable.

Best,

Thomas

[ijs12fly]

On 6/17/2019 at 9:03 PM, tomatl said:

Made some progress in solving the CO issue. I taped the edge of the wing roots with duct tape. Also, I found a belly panel screw missing under the plane right downstream of the exhaust, which I also taped (see pictures below). With this, CO dropped to 0 ppm in cruise, with both cowl flaps in or out. I still have a little before landing with gear/flaps down. Next time I fly, I‘ll remove the tape on the wing roots and see if I still get zero. I this case, the fix would be to just put a bigger screw into the worn out thread. If it‘s the roots, they would need to be removed and re-taped below. That would be quite costly. I hope, it‘s just the screw.






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Hi @tomatl  So are you saying the panel with the 2 pieces of Red tape is where all your CO problems were coming from and it had nothing to do with the wing roots?  And by repairing a few screws and tightening screws that fixed it.  I have a few holes in my rudder boots that i believe are above that panel and perhaps that is also a source of my problem.   My home airport is one airport away form 39N so I may have to visit that shop.   Do you have a contact at the shop you worked with?

I am also chasing a CO issue for 2 years now.  Mine happens under full power in climb, and even during high power in cruise.  24^2 and its usually pretty good, and that is with cabin venting on. 

 

 

 

 

 

[A64Pilot]

I believe that “Clay” someone had isn’t clay, it’s sealant used in the HVAC industry for sealing the copper lines going through buildings etc, there is also a tape that’s like a tar, both are actually not bad for this type of use, of course not forward of the firewall, and I’d try burning some even aft of the firewall, that stuff may be flammable for all I know.

Used to be you could get zinc chromate putty that woud have been excellent, but I believe it caused cancer in California and you can’t find it anymore, or I can’t anyway, if someone finds a source let me know.

Edited May 14, 2021 by A64Pilot

[PT20J]

Here’s what I used to plug the aft bulkhead penetration for the tailcone wiring. My picky IA was fine with it. https://www.homedepot.com/p/t/100212441?langId=-1&storeId=10051&catalogId=10053&N=5yc1vZ1xi0&R=100212441

In my plane the source of the CO was the door seal. If the seal is old and compressed (or has been replaced but not correctly positioned) it leaks at the lower front corner and allows outside air to enter.

Remember that CO is a product of incomplete combustion so the engine produces more CO at rich mixtures. In my case, this translated to more CO during climb. Highest I ever got with a Sensorcon clipped to the right map pocket was 40 ppm. It’s zero after replacing the door seal.

Skip

[carusoam]

Great reminder...

1) Using the CO meter... it can be moved around the cabin to narrow down the source...

2) Helps to have a helper while you fly the plane...

3) Let me know if you will be visiting 39N... that’s my home drome...

Best regards,

-a-

[skyfarer]

Ah this is why I love MooneySpace!  I'm starting to chase down a CO problem in my new to me Mooney Bravo this weekend.  It's recently had new carpet installed, a new door seal (that whistles when the wind angle is right so def needs adjustment), and new exhaust clamps.

In my case, CLOSING the cowl flaps causes the CO levels to drop from 50-100ppm to 0-10ppm.  So in cruise it's just fine, it's the climb with open cowl flaps that has me concerned.

I'm going to start with getting the door to seal better, and look at the tail bulkhead. If after this I still have high CO levels,  I'll pull the carpet out and tape up anything that looks like CO can seep through.

[LANCECASPER]

4 hours ago, skyfarer said:

Ah this is why I love MooneySpace!  I'm starting to chase down a CO problem in my new to me Mooney Bravo this weekend.  It's recently had new carpet installed, a new door seal (that whistles when the wind angle is right so def needs adjustment), and new exhaust clamps.

In my case, CLOSING the cowl flaps causes the CO levels to drop from 50-100ppm to 0-10ppm.  So in cruise it's just fine, it's the climb with open cowl flaps that has me concerned.

I'm going to start with getting the door to seal better, and look at the tail bulkhead. If after this I still have high CO levels,  I'll pull the carpet out and tape up anything that looks like CO can seep through.

In the meantime I would put 1/2" wide 3M #4516 self-adhesive seal strip on the fuselage where the door frame seal meets the cabin. It's thin enough that it won't hurt your hinges and it should at least eliminate your wind noise. It will help you to see whether the CO problem is mainly with the door seal. It will take you 10-15 minutes.

[skyfarer]

4 hours ago, LANCECASPER said:

In the meantime I would put 1/2" wide 3M #4516 self-adhesive seal strip on the fuselage where the door frame seal meets the cabin. It's thin enough that it won't hurt your hinges and it should at least eliminate your wind noise. It will help you to see where the CO problem is mainly with the door seal. It will take you 10-15 minutes.

 

 

Thanks Lance!  Definitely going to do this first since it's quick and easy.

[LANCECASPER]

8 minutes ago, skyfarer said:

Thanks Lance!  Definitely going to do this first since it's quick and easy.

If you need it quick: https://www.amazon.com/3M-Vinyl-Black-Length-Width/dp/B000SPOQ8E/ref=sr_1_2?crid=QUINZYZKQS9Z&keywords=3M+%234516+1%2F2"&qid=1650650240&s=industrial&sprefix=3m+4516+1%2F2+%2Cindustrial%2C158&sr=1-2

or this would work for less money and same specs (1/16" thick): https://www.amazon.com/dp/B08LDX2MR5/ref=syn_sd_onsite_desktop_496?pd_rd_plhdr=t&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyWU1PM1BZUllOVTdGJmVuY3J5cHRlZElkPUEwMDkzNDU3MkQ5WFZFUElFQ0laVCZlbmNyeXB0ZWRBZElkPUEwNTM5MzgyMTYxRlM5QjdGQTAxJndpZGdldE5hbWU9c2Rfb25zaXRlX2Rlc2t0b3AmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1

[Schllc]

Easier way to rule out the door is to tape it up from the inside using blue painters tape. 
I have never been in a Mooney that doesn’t have some noise from the door. 
some worse than others, and I’m not saying every single one, but the 20+ I’ve been in all made noise. 
even the two ultra’s I’ve owned (now it’s two doors to leak)

I just carry a roll of tape all the time and if I’m taking a long trip I tape ‘‘em off. 
It’s not classy but it works!

[carusoam]

When searching for CO leaks…

The CO detector company has a tube/pump attachment that makes a better tool for the hunt…

https://sensorcon.com/products/sensorcon-carbon-inspector-accessory-kit?variant=6436387588

Best regards,

-a-

[LANCECASPER]

2 hours ago, Schllc said:

Easier way to rule out the door is to tape it up from the inside using blue painters tape. 
I have never been in a Mooney that doesn’t have some noise from the door. 
some worse than others, and I’m not saying every single one, but the 20+ I’ve been in all made noise. 
even the two ultra’s I’ve owned (now it’s two doors to leak)

I just carry a roll of tape all the time and if I’m taking a long trip I tape ‘‘em off. 
It’s not classy but it works!

 

My post from a few months ago.

I have never flown in a piston single quieter than mine after the 3m seal was added. I'd rather do it once and not add blue painter's tape to my cruise checklist. 

 

[Schllc]

1 hour ago, LANCECASPER said:

 

My post from a few months ago.

I have never flown in a piston single quieter than mine after the 3m seal was added. I'd rather do it once and not add blue painter's tape to my cruise checklist. 

 

No argument for that, I just have not been as lucky sealing the door.

I have added weather stripping, I’ve changed door seals, I’ve paid a MSC to tweak the doors.  I haven’t had anyone successfully stop the minor leaking that presents in cruise. 
If I could solve it with the 3m I’d be extremely happy….

Only one of them leaked water when it rained on the ramp so I thought I was doing pretty well!

I really think it’s either the luck of the draw, a whole lot of persistence that eliminates the drafts, or maybe both….

I wouldn’t say most of them were troublesome, just something you could hear.

When you tape the doors it’s 100% effective for the noise, so on a long trip, it’s the backup plan…

[skyfarer]

@LANCECASPER you are both, a gentleman AND a scholar.  After tightening up the door latch, I could still see a bit of daylight through the door jam when closed. I applied the foam tape as you described, then took her up with the CO monitor. 0-5 ppm! And the door was quiet, no more whistling. Looked to me like you (or someone else) had already done this to 794RS because I scraped off some old foam tape left in a few spots around the bottom of the door frame.

[LANCECASPER]

31 minutes ago, skyfarer said:

@LANCECASPER you are both, a gentleman AND a scholar.  After tightening up the door latch, I could still see a bit of daylight through the door jam when closed. I applied the foam tape as you described, then took her up with the CO monitor. 0-5 ppm! And the door was quiet, no more whistling. Looked to me like you (or someone else) had already done this to 794RS because I scraped off some old foam tape left in a few spots around the bottom of the door frame.

When I bought N794RS in late 2006 I hadn't discovered the 3M tape yet, but I wish I had. I remember that door seal being very loud on that airplane. When I had the interior panels recovered by AeroComfort I put in Soundex insulation behind the interior panels hoping it would be quieter, but I've come to realize on a Mooney the first place to look is the door seal, then  next is the baggage seal. Glad it worked for you.

In flight if you are still sometimes getting 5 PPM then the next places to look are the baggage door (do the same), make sure that the belly panel isn't missing any of the camlocks. If it is then cover that hole with tape and go back up again. You could also check the firewall for any leaks to the cabin. If that's the case then you may have a bad exhaust gasket as well.

[thinwing]

On 6/5/2019 at 8:08 AM, tomatl said:

Hi all, my mechanic filled the gap with some type of putty (only from the tail cone side) after I wrapped the cables with a piece of leather (that I cut out from the underside of our couch cushion when my wife was not looking). Unfortunately, the CO levels did not change. I am at a loss here. When I flew the plane back home from the shop I got 0 on takeoff and climb out, 12-20 on cruise in the front part of the cabin (more in the back).

Perhaps the door seal is still leaking?


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more likely the entire belly pan is the issue...on approach and takeoff,AOA change from cruise is causing exaust stream to closely adhere to the belly.Edge seal gets worn and removed due to constant removal and oil exposure.It is a simple rtv or proseal bead applied during mfd.Remove belly pan and inspect