Carbon Monoxide Questions

[AdamZ]

With the cold Wx not to far away and Ted's recent post about a cracked exhaust system, I have been thinking about CO poisioning. First off a few questions:

1) Do I assume correctly that CO poisioning is more likely in aviation in winter months since we use our heat which is not used in the warmer months. I'd assume a cracked exhaust system would introduce CO into the heat exchanger.

2) CO often kills at night in homes while folks are asleeep and may not notice the effects of increased CO levels. While CO may be insideous and creep up on you it dose have signs such as incrased exhaustion and head aches before it incapacitates you. Since pilots are perhaps more aware of CO exposure that the general public and since we may carry even the cheapest $7.00 CO detector cards in our planes I'm thinking we may have the opportunity to be forwarned that we are being exposed to CO. In such a case would opening the outside airvents and the pilots mini window get enough fresh air in the cockpit to allow you time to get the plane safely on the ground?

 

[Everskyward]

1) Do I assume correctly that CO poisioning is more likely in aviation in winter months since we use our heat which is not used in the warmer months. I'd assume a cracked exhaust system would introduce CO into the heat exchanger.

The only instance I can remember of someone getting CO poisoning in an airplane happened in the summer, in a C-210. It's been too long so I don't know exactly what was broken but I think it was part of the exhaust system. They were lucky that it only gave them bad headaches.

 

[wanttaja]

...Since pilots are perhaps more aware of CO exposure that the general public and since we may carry even the cheapest $7.00 CO detector cards in our planes I'm thinking we may have the opportunity to be forwarned that we are being exposed to CO. In such a case would opening the outside airvents and the pilots mini window get enough fresh air in the cockpit to allow you time to get the plane safely on the ground?

Depends on the plane. I have a friend who got a bad case of CO poisoning in a Starduster...an open-cockpit plane. I ran a check in my own open-cockpit Fly Baby with a detector with a digital output, and got a variety of readings depending on various factors.

The cockpit is a low-pressure area, so just opening a side window might make the problem worse. If you can get ram air into the cockpit, go for it.

Ron Wanttaja

 

[jesse]

1) Do I assume correctly that CO poisioning is more likely in aviation in winter months since we use our heat which is not used in the warmer months. I'd assume a cracked exhaust system would introduce CO into the heat exchanger.

A really bad exhaust issue could potentially be an issue in the summer. In general though you need to have the cabin heat on...which permits that air to enter the cockpit.

2) CO often kills at night in homes while folks are asleeep and may not notice the effects of increased CO levels. While CO may be insideous and creep up on you it dose have signs such as incrased exhaustion and head aches before it incapacitates you. Since pilots are perhaps more aware of CO exposure that the general public and since we may carry even the cheapest $7.00 CO detector cards in our planes I'm thinking we may have the opportunity to be forwarned that we are being exposed to CO. In such a case would opening the outside airvents and the pilots mini window get enough fresh air in the cockpit to allow you time to get the plane safely on the ground?

I had it happen in a DA-20-C1 once. The sound in the cockpit sounded different and it gave me a headache and made me sleepy. I knew what it was, turned the cabin heat off, and opened up the "blow-your-toupee-off" vents.

 

[poadeleted20]

1) Do I assume correctly that CO poisioning is more likely in aviation in winter months since we use our heat which is not used in the warmer months.

Yes.

I'd assume a cracked exhaust system would introduce CO into the heat exchanger.

That's one way to do it. Another is with leakage from the engine compartment into the heater hoses leading to the cockpit. In addition, if you have a Janitrol heater, that can have failures which will introduce CO.

2) CO often kills at night in homes while folks are asleeep and may not notice the effects of increased CO levels. While CO may be insideous and creep up on you it dose have signs such as incrased exhaustion and head aches before it incapacitates you.

True, assuming that in your increasingly incapacitated state you can put it all together and identify the problem.

Since pilots are perhaps more aware of CO exposure that the general public and since we may carry even the cheapest $7.00 CO detector cards in our planes

Those cards are almost worse than nothing, since they may give you the false idea that you'll get some warning before you have big trouble. Get a good electronic detector!

In such a case would opening the outside airvents and the pilots mini window get enough fresh air in the cockpit to allow you time to get the plane safely on the ground?

Probably yes, maybe no. Depends on the nature of the failure, how much CO you've already assimilated (takes a long time to flush), what you can do to shut off the CO intake, and the clean air flow you can generate.

 

[Ted]

The Mooney had a cracked exhaust pipe on it early last winter (when the cabin heat was getting used a lot). After flying it for about 90 minutes and landing I didn't feel great. Later it turned into a really bad headache and feeling all out of sorts for a few hours. We found the exhaust stack cracked upon inspection. Neither the owner nor I had any issues previously, but we also didn't have the heater on much.

I'd agree that those little cards are useless. An electric CO detector from WalMart only costs a bit more and is far, far more useful. I should buy one for the Aztec since, as Ron pointed out, that's another potential failure mode of Janitrol heaters (my favorite engineering marvel, as we all know ). Fortunately the exhaust being cracked on the Aztec didn't introduce any CO in the cabin, so that is a plus.

From my experience, I'd say it's something pilots should be careful of. We may be more aware of our surroundings, but we still have to fly (and land) the plane.

 

[dmccormack]

I'd agree that those little cards are useless. An electric CO detector from WalMart only costs a bit more and is far, far more useful.

Interesting. I have one of those cards but this is the first I've heard that they don't work.

I supose you mean the battery powered CO detectors?

(The heat works almost too well in the Chief -- I suppose that has to do with very little volume to actually heat!)

 

[Ted]

Yeah, the little battery-powered ones that are the same size as smoke detectors are the way to go. Significantly more useful, and roughly the same price.

 

[RogerT]

I use a digital one. Preferably one that reads down to 5 ppm. This is the one
I have:

http://www.aircraftspruce.com/catalog/pspages/co300.php

I work in the hangar using a propane tube heater .. 80,000 btu ... when
it's cold out. Used it all morning this morning in fact. When it stays over
50 for long I can feel it. 25 to 30 doesn't seem to be an issue. When
it's hitting 50 I'll turn off the heater a while and let it drop.

You can get exhaust fumes in the cockpit any time .. not just from the
heater, even though that's the most common. Things like bad wing
root seals or other openings can let fumes in from the exhaust on the bottom
of the plane.

RT

 

[Geico266]

The Mooney had a cracked exhaust pipe on it early last winter (when the cabin heat was getting used a lot). After flying it for about 90 minutes and landing I didn't feel great. Later it turned into a really bad headache and feeling all out of sorts for a few hours. We found the exhaust stack cracked upon inspection. Neither the owner nor I had any issues previously, but we also didn't have the heater on much.

I'm no MD so maybe one would chime in. It is my understanding that CO saturates the body and robs the bloods ability to carry O2. You can receive a lethal dose, land, and still collapse into a coma due to the length of time it takes to expel the CO. Also, 9 times out of -10 you will not be able to detect you are having trouble. By the time you have a headache the dose may be high enough to be fatal. It's not as simple as getting fresh air, that is my understanding anyway.

Hopefully, someone with more degrees than me will chime in. This is too serious an issue for internet gossip.

I use a home CO monitor, but it uses a 9v battery. Works great for $30.

 

[twdeckard]

It is my understanding that CO saturates the body and robs the bloods ability to carry O2.

This is true, the hemoglobin has a higher affinity for CO than O-O. The blood cells won't readily surrender the monoxide.

The wikipedia article on poisoning was pretty chilling. I am going to get one of those hardware store units and stuff it in my saddle bag.

My neighbor is prone to acute migranes and after an un-managable bout they discovered a defective furnace. His family had suffered only mild symptoms but it wasn't until a doctor was musing about causes that they connected with the recent installation. Its my theory that he has a PFO and was the canary in the mine that saved his family!

 

[AuntPeggy]

Here is another source of CO detectors for the cockpit. https://www.aeromedix.com/category-exec/parent_id/1/category_id/7/nm/Carbon_Monoxide_Detectors Several reasons why you need a super-sensitive detector. At altitude, you are breathing less oxygen, so carbon monoxide works faster. At altitude, it takes awhile to get to a landing place. To say nothing of the intellectual activity of flying a plane.

My story: One evening the Fire Chief knocked on the front door, waking me up. I had fallen asleep on the sofa while watching TV and Hubby had gone upstairs to bed without waking me. The neighbors had seen smoke in our basement and called the fire department. Turns out a defective furnace was filling the house with CO. I had a very hard time waking up and when I did, felt faint, with difficulty catching my breath. Fire Chief sat on the porch with me for an hour before he would let me back into the house. Meantime, firemen turned off the furnace, brought huge fans into the house and blew all the warm air out, making sure the house got nice and cold.

 

[AdamZ]

So am I to understand that those dots on the cards aren't worth squat? I guess I could save $100 by just buying a house hold one with a 9v battery and stick it in the back seat.

 

[Rob Schaffer]

Bob and I just put a little pager sized CO detector in the plane that has it's own battery instead of the CO Detector Card. I don't know where he got it, but its a nice little unit.

 

[sba55]

1) Do I assume correctly that CO poisioning is more likely in aviation in winter months since we use our heat which is not used in the warmer months. I'd assume a cracked exhaust system would introduce CO into the heat exchanger.

Yes, that's the primary way in which it can happen. Yet another reason to fly lean of peak - if you do, you'll reduce potential CO in the exhaust by a factor of 100. Even with a leak in that case, it probably wouldn't affect you quickly enough not to be able to take counter-measures.

So am I to understand that those dots on the cards aren't worth squat? I guess I could save $100 by just buying a house hold one with a 9v battery and stick it in the back seat.

Yes, and that's exactly what I do. Works really well; and it's so loud that it's hard to miss.

 

[AuntPeggy]

Because kitchen stoves normally produce 5 to 15 PPM carbon monoxide, household detectors usually sound an alarm at levels higher than that. I think it is around 50 to 70 ppm, but I cannot say for sure. You probably want to spend the extra $100 for a sensitive detector.

 

[Areeda]

There are a couple of big differences between the aviation CO detectors and the household detectors.

This is from memory so please read the specs if you go for the cheaper home units. Most home units will not sound an alarm until CO concentration is 30-50 ppm for over 5 minutes while the aviation detectors alarm anytime CO concentration is over 5 or 10 ppm.

As to the physiology, once CO binds with hemoglobin it doesn't release. Red blood cells are completely replaced about every 120 days. My understanding is that the treatment for acute CO poisoning is a blood transfusion.

Joe

 

[RogerT]

http://www.osha.gov/OshDoc/data_General_Facts/carbonmonoxide-factsheet.pdf

 

[Let'sgoflying!]

we just happen to be discussing this topic here.

From the link above;
"The OSHA PEL is 50 parts per million (ppm).
OSHA standards prohibit worker exposure to
more than 50 parts of the gas per million parts
of air averaged during an 8-hour time period.
■ The 8-hour PEL for CO in maritime operations
is also 50 ppm."

The selling point for the CO Experts device is sensitivity below 50ppm. I suspect that
a) if a person at work can safely tolerate 50ppm for 8 hours, then I could tolerate that much in an airplane for a typical long flight of less than half that time (hence a household device would work fine as it will notify at 50ppm)
b) if an exhaust cracks, I bet the cabin (what, about 100cu ft) will likely go way over 50ppm pretty quickly (hence the household device will do fine as it will notify readily)
c) the CO Experts device I had constantly gave false alerts. This would be in the summer when I had the cabin door open during taxi. Kind of annoying. Yes, the device was working as it should.
But knowing that the exhaust is blowing in the open door is not useful information. The beeping would often not stop til climbout and besides being aggravating, I would have to pull it out and look to see I was not over 50ppm during a busy phase of flight.

I am going to go with a cheaper household device.

 

[wby0nder]

some years ago a guy was flying across MO I think, in a light single, and passed out from CO. He woke up in a corn field after the plane ran out of gas and crash landed itself. Doctors said that if it hadn't run out of gas he would have died from the CO. I remember reading about this in the papers and hearing it on regional news so I don't think it's a myth.