Right way to handle Carbon Monoxide

[201er]

Right way to handle Carbon Monoxide:

 

Wrong way (no offense, Dan’s the man!)

or

Having good detection, keeping head straight, and landing ASAP. That’s the way to go. Glad Dan is ok and has convinced the majority of us to get detectors. For those who haven’t, see above and think about how you will handle it.

[201er]

Any Mooney specific suggestions to share such as how to set the cowl flaps, power, etc in the event of a sudden high Carbon Monoxide reading?

[varlajo]

6 minutes ago, 201er said:

Any Mooney specific suggestions to share such as how to set the cowl flaps, power, etc in the event of a sudden high Carbon Monoxide reading?

Storm window: OPEN 

[201er]

9 minutes ago, varlajo said:

Storm window: OPEN 

You sure that wouldn’t act like a Venturi and suck more CO into the cabin? I’ve never opened in flight so I’m not sure if it blows in or out?

[carusoam]

Things to consider…

where the CO is getting out.

in a TC’d Mooney, the hot side of the TC… can form a crack and leak… or the V clamps have been known to let go…

it will be leaking very hot gasses and may start destroying things under the cowl…

 

in a NA Mooney, the source of CO is most often a cracked muffler allowing CO into the heater muff system… look for a sign… moisture condensing inside on the windows… and a headache…

 

anything that stops airflow into the cabin…

or dilutes the concentration of the CO that is in front of the cabin…

can be helpful…

 

next step is to get fresh air into the cabin, airscoop in the pilots window may be helpful…

our cabins are running under a slight vacuum…

but opening a door in flight, will surely cause a windstorm in the cabin…

 

either way… a sudden increase in CO is a land now situation… nearest airport will work in most cases…

a broken TC exhaust system… the land now program can include the nearest open field…  first determine if you have a fire under the cowl…

@mike_elliott has some interesting experience in this area…

I used my Mooney’s CO detector to find an exhaust leak in my firebird…

(the firebird is gone…)

remember… CO absorbed in your body takes longer to leave, than the length of your flight… 

battling the CO you have collected, it will be better to be at lower altitudes, and have O2 to help breathing…

PP thoughts only… not a mass transport phenomena guru…

Best regards,

-a-

 

[takair]

Generally the storm window sucks, it’s why it will stay close with the little latch open.  That said, I guess your point is that it may draw in more CO!  Good thought.  I guess I would close the heat and open the overhead vents and blow that in my face.

[carusoam]

Some modern Mooney overhead vents…

are supplied with air from a NACA duct at the base of the tail fin…

Don’t be surprised to find that air from the cowling somehow gets brought to the tail’s air intake…

Some CO seeking MSer… found his CO leak entering the cabin from the avionics wires running to the tail… were not adequately sealed at the penetration.

-a-

[Ragsf15e]

If not already, lean of peak might help a little as you get it on the ground.  Rich mixture makes more CO.  Either way it’s bad.

[N201MKTurbo]

I had a CO incident about 35 years ago. My muffler got a 1/4 inch crack in it. 
 

I was flying from Denver to Rapid City. When I got there I felt terrible. Like a real bad hangover. I bought a CO spot detector. It turned black in about 10 seconds. It was the middle of winter and it was very cold out side. I flew home with the heater off and all the vents open. The shivering kept me awake.
 

[Will.iam]

If you have the altitude and the CO is really bad, pulling the mixture to cutoff will eliminate the CO (no fuel no combustion thus no CO) you can always add back in the mixture to help get to a landing site once you are close to landing. 

[dkkim73]

I wonder which Mooney vents are least likely to pick up exhaust from various sites inside the cowl.  I might guess the side cowl vents are least prone (by the pilot and copilot outside legs). 

The dorsal fin vent supplies all the roof vents I believe... Wonder if the spiraling slipstream will let exhaust leak fumes in there.

What about "cabin vent" on the console pillar? Does that pull from up front? 

I know on my plane the heater is wrapped around the high side crossover pipe from the hot side of the turbos. Worth turning that off if the detector goes bonkers. 

I've only had CO warnings on the ground with door or storm window open... Usually with light crosswinds etc. Knock on wood....

[IvanP]

O2 on full flow regardless of altitude (possibly with mask if available), heater off, overhead cabin vents open to create downflow in the cabin, land as soon as practicable. 

[slowflyin]

LOP will drastically decrease the CO concentration.  On a hot day I often taxi with the door ajar.  The CO detector will go nuts without leaning.   If I lean to roughness it will decrease back down to below 10 very quickly.   I experienced the same at cruise when a shop incorrectly installed the belly panel.   All that being said, if you suspect a V-band is letting go, increasing the exhaust gas temp might not be productive.  

[Yetti]

3 hours ago, slowflyin said:

LOP will drastically decrease the CO concentration.  On a hot day I often taxi with the door ajar.  The CO detector will go nuts without leaning.   If I lean to roughness it will decrease back down to below 10 very quickly.   I experienced the same at cruise when a shop incorrectly installed the belly panel.   All that being said, if you suspect a V-band is letting go, increasing the exhaust gas temp might not be productive.  

You probably need to pull the carpet and replace all the duct tape with aluminum tape.    That said my F has a 4"x4" louvered vent out the pilot's side by the rear passenger seat.   Open up the vents.   Should clear it.

[varlajo]

13 hours ago, takair said:

Generally the storm window sucks, it’s why it will stay close with the little latch open.  That said, I guess your point is that it may draw in more CO!  Good thought.  I guess I would close the heat and open the overhead vents and blow that in my face.

Correct; if both the overhead vent and storm window are open, there is pretty dramatic down/outward airflow that should take much of exhaust-produced CO with it. 

[varlajo]

13 hours ago, 201er said:

You sure that wouldn’t act like a Venturi and suck more CO into the cabin? I’ve never opened in flight so I’m not sure if it blows in or out?

Out. Ask me how I know 

[N201MKTurbo]

13 hours ago, 201er said:

You sure that wouldn’t act like a Venturi and suck more CO into the cabin? I’ve never opened in flight so I’m not sure if it blows in or out?

You should open it. That's what it is there for. there used to be a sticker that said to not open it above 150 MPH. actually, it is OK to open it, but be careful closing it, it sucks pretty hard. Close it with your fingers around it and then slide them out. 

[Rick Junkin]

My Sensorcon alarmed just as I was entering the cloud bases at about 700 feet on departure. I had the detector clipped on my shoulder belt in the middle of my chest, and by the time I could look at it the display was climbing through 100. I immediately declared an emergency and started a climbing turn back toward the field while requesting vectors to the ILS final. I shut all of the vents, and then as I recall re-opened the overhead vents when I saw the display above 200. That was the last time I looked at it until I got on the ground. The approach controller basically gave me a turning PAR that rolled me out on short final and descended me below the weather. I was sure I was below his MVA, but he did an awesome job. The whole thing was over in a matter of minutes.

We found a loose v-band, but my door was a little wonky at that time too and I think the door wasn't shut properly and there was probably a door seal leak, considering the super high numbers. We worked the v-band and the door. I waited a day to make sure I didn't have any symptoms after that exposure and then made an uneventful flight home. I didn't see a doc, but I might do that if it happened again today.

Another thing that can help is to reduce the AOA and let the slipstream flow the exhaust around the airplane rather than dragging the airplane through it at higher AOA. So stop climbing and speed up if you can without using too much power, in addition to leaning as much as practical.

[MikeOH]

The following exposure table may be helpful:

 

[slowflyin]

2 hours ago, Yetti said:

You probably need to pull the carpet and replace all the duct tape with aluminum tape.    That said my F has a 4"x4" louvered vent out the pilot's side by the rear passenger seat.   Open up the vents.   Should clear it.

I don't get high CO unless the door is open during hot weather taxi ops but I agree, the tape and proper door seals are important.  

[N201MKTurbo]

My symptoms corresponded to the 400 PPM on the chart above. The trip to KRAP took 2 hours and I had the headache and nausea. the symptoms did not change on the trip home with the heater off. 

[dkkim73]

Was looking around at the physiology and treatment. Found an interesting bit on UpToDate (treatment ref. for docs):

 

"High-flow oxygen — In a patient with suspected or confirmed CO poisoning, we recommend initial treatment with high-flow (100 percent) normobaric oxygen via nonrebreathing face mask, regardless of pulse oximetry or arterial PO₂. Elimination of CO starts once the patient is removed from the exposure and is almost exclusively via the pulmonary circulation through competitive binding of hemoglobin by oxygen. The half-life of COHb in a patient breathing room air is approximately 250 to 320 minutes; this decreases to 75 to 90 minutes with high-flow oxygen (>15 L/minute) provided via a nonrebreathing mask [61]. Normobaric high-flow oxygen therapy is relatively safe and available, and it hastens the elimination of COHb even though evidence does not exist that, compared with breathing room air, supplemental oxygen actually limits or prevents delayed neuropsychiatric syndrome (DNS). In a trial of CO-poisoned patients, six-week cognitive sequelae were lower in patients who were treated with normobaric oxygen compared with patients not receiving supplemental oxygen (41 [60/146] versus 53 [9/17] percent), but this finding did not achieve statistical significance [62]."

Looking at those half-lifes, you would not expect to be OK on a return trip soon after fixing the problem. 

I had forgot the part about competitive binding with O2. Those facts would imply it has to do with the partial pressure of O2, which would argue for max O2 supplementation in flight and probably a descent. Interesting that they will also "dive" sicker patients using a hyperbaric chamber. I don't have much personal experience in this problem so just passing on for interest. 

BTW your standard pulse oximeter will not work normally (it sees the carboxyhemoglobin similarly and will think that "color" of blood is carrying oxygen). So don't put on a pulse ox in the presence of an alarm and think "oh I'm ok now". OTOH if the pulse ox is low, you might have a second problem (too high, O2 system not working, etc). as well. 

 

 

[N201MKTurbo]

So, I was not OK per se. But I didn't get worse. I didn't get better for three days after. 

I think with anything less than 800 PPM, a normal landing should be fine. Even at 800 PPM you have 45 minutes until you get sick, and 2 hours until you become incapacitated. 

Turning things into an emergency and doing unusual approaches when they are not necessary is probably more dangerous than the CO poisoning.

[201er]

16 minutes ago, N201MKTurbo said:

Turning things into an emergency and doing unusual approaches when they are not necessary is probably more dangerous than the CO poisoning.

Not if you pass out...

When's the last time you've had your CO detector calibrated? I wouldn't get overly confident about the reading and chart to decide how much time I have. Get on the ground ASAP. But it's true, the airplane isn't on fire and the engine isn't quit so get down safely without wasting time.

[Rick Junkin]

25 minutes ago, N201MKTurbo said:

I think with anything less than 800 PPM, a normal landing should be fine. Even at 800 PPM you have 45 minutes until you get sick, and 2 hours until you become incapacitated. 

The important thing to consider here is that everyone is affected at different rates and as with hypoxia, judgement can be affected almost immediately. Also if you have a CO problem, the source of the CO could be the more serious problem and that could devolve quickly.

I agree that getting on the ground as soon as practical is more appropriate than as soon as possible without indications of other issues. No need to rush into anything without "winding the clock" and making a considered assessment of the situation. But make an early decision on a course of action and get it in motion and communicated as soon as possible, just in case you start losing the ability to make your best decisions. Whether or not to declare an emergency is a PIC call left to his/her judgement and assessment of the situation.