Carbon monoxide ...
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Carbon monoxide ...
Wierd. Yesterday I took some friends flying. We did a couple of hours with no issues. On the way home they wanted some photos of their house, so I flew a few fairly heavily-banked orbits over the required spot.
I always carry a pretty sensitive CO detector on board (not the little paper ones, but an electronic one), and all of a sudden it went mad. It continued for some time after I'd pulled out of the orbits and continued en route.
Anyone any theories ? Ingesting my own exhaust, perhaps ?
I always carry a pretty sensitive CO detector on board (not the little paper ones, but an electronic one), and all of a sudden it went mad. It continued for some time after I'd pulled out of the orbits and continued en route.
Anyone any theories ? Ingesting my own exhaust, perhaps ?
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Ingesting my own exhaust, perhaps ?
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I bought mine in B&Q. It's perfect size to slot into the pedastal.
It used to live on the parcel shelf, until the above-mentioned incident when we decided it needed to be somewhere closer to hand. Not because it'll detect CO any better, but because it makes such an almighty racket when triggered that by the time we managed to fish the damn thing out the back we all had a headache from the noise!
It used to live on the parcel shelf, until the above-mentioned incident when we decided it needed to be somewhere closer to hand. Not because it'll detect CO any better, but because it makes such an almighty racket when triggered that by the time we managed to fish the damn thing out the back we all had a headache from the noise!
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I would suspect that you were flying pretty precise orbits, and you simply flew through your own exhaust from the previous pass. If you had cabin air or heat elected, it pulled in air with exhaust in it. Once you trigger a CO detector, they can take a while to clear, so you could have been straight and level for a while before it recognized it was in clear air.
While flying a Cessna 207 with very advanced atmospheric resaerch equipment operating on board, I flew through my own exhaust of probably 15 to 20 minutes earlier, and the sensor went wild. The polution stays in the air for a long time.
It that situation I would not worry about safety. On the other hand, CO in the cabin for a period of 15 minutes or more is a serious issue, requiring definate "clear the air" action without delay. Flying an aircraft with het muff cabin heat and no effective CO detector is very foolish.
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While flying a Cessna 207 with very advanced atmospheric resaerch equipment operating on board, I flew through my own exhaust of probably 15 to 20 minutes earlier, and the sensor went wild. The polution stays in the air for a long time.
It that situation I would not worry about safety. On the other hand, CO in the cabin for a period of 15 minutes or more is a serious issue, requiring definate "clear the air" action without delay. Flying an aircraft with het muff cabin heat and no effective CO detector is very foolish.
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Don't wait too long to see if it's a false alarm. Treat an environmental emergency in the cockpit as just that; an emergency. Carbon monoxide has a tendency to remain with a red blood cell 240 times longer than oxygen does, or more accurately put, the red blood cell has a greater affinity for CO than O2.
What this means for you is that while you can recover quickly from an oxygen-deprived state such as hypoxia, by getting good ventilation, oxygen, and pressurized air...the same isn't true of carbon monoxide poisoning. It's a slow recovery, and you may not have the time. Even with 100% oxygen in a pressurized mask delivery, it may not help. Point is, take any indication of carbon monoxide in the cockpit very seriously.
The most common source of CO in the cockpit, of course, is engine exhaust. In automobiles, cabin heat is obtained by blowing air over small radiator full of circulating engine coolant. Not so in most light airplanes. We use shrouds over the exhaust through which outside air is funneled, warmed, and put into the cabin. These shrouds are notorious for slippage, often held in place with nothing more than PK sheet metal screws, hose clamps, or both. They tend to slip out of position, admitting any leaked exhaust gas, and the tend to slip and cause wear on the support cones beneath...leading to exhaust in the cockpit. You may not smell it, and certainly you won't smell CO (carbon monoxide)...but it may be lethal all the same.
Assume that any indication you have of carbon monoxide in the cockpit is real. Ventilate as required, land as soon as practicable. You can always sort the matter out on the ground. If you wait on the assumption that it's probably not a big deal, you may reach the ground in an unintended and undesirable manner.
What this means for you is that while you can recover quickly from an oxygen-deprived state such as hypoxia, by getting good ventilation, oxygen, and pressurized air...the same isn't true of carbon monoxide poisoning. It's a slow recovery, and you may not have the time. Even with 100% oxygen in a pressurized mask delivery, it may not help. Point is, take any indication of carbon monoxide in the cockpit very seriously.
The most common source of CO in the cockpit, of course, is engine exhaust. In automobiles, cabin heat is obtained by blowing air over small radiator full of circulating engine coolant. Not so in most light airplanes. We use shrouds over the exhaust through which outside air is funneled, warmed, and put into the cabin. These shrouds are notorious for slippage, often held in place with nothing more than PK sheet metal screws, hose clamps, or both. They tend to slip out of position, admitting any leaked exhaust gas, and the tend to slip and cause wear on the support cones beneath...leading to exhaust in the cockpit. You may not smell it, and certainly you won't smell CO (carbon monoxide)...but it may be lethal all the same.
Assume that any indication you have of carbon monoxide in the cockpit is real. Ventilate as required, land as soon as practicable. You can always sort the matter out on the ground. If you wait on the assumption that it's probably not a big deal, you may reach the ground in an unintended and undesirable manner.
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SNS is right, CO indications should be taken seriously and intermittent CO warnings may be symptomatic of a slowly developing problem.
When training, there was one particular aircraft which made me feel slightly 'off colour' after using it and later gave my instructor a splitting headache by the end of the lesson.
The CFI flew it and the engineers prodded it two or three times and they all swore it was fine. Then one day the CO card went to solid black during a power check and eventually they discovered that there had been a developing crack in an exhaust manifold.
Personally, like any other odd indication on an aircraft, I would get it checked out.
When training, there was one particular aircraft which made me feel slightly 'off colour' after using it and later gave my instructor a splitting headache by the end of the lesson.
The CFI flew it and the engineers prodded it two or three times and they all swore it was fine. Then one day the CO card went to solid black during a power check and eventually they discovered that there had been a developing crack in an exhaust manifold.
Personally, like any other odd indication on an aircraft, I would get it checked out.
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I bought mine in B&Q. It's perfect size to slot into the pedastal.
It used to live on the parcel shelf, until the above-mentioned incident when we decided it needed to be somewhere closer to hand. Not because it'll detect CO any better, but because it makes such an almighty racket when triggered that by the time we managed to fish the damn thing out the back we all had a headache from the noise!
It used to live on the parcel shelf, until the above-mentioned incident when we decided it needed to be somewhere closer to hand. Not because it'll detect CO any better, but because it makes such an almighty racket when triggered that by the time we managed to fish the damn thing out the back we all had a headache from the noise!
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Carbon monoxide has a tendency to remain with a red blood cell 240 times longer than oxygen does, or more accurately put, the red blood cell has a greater affinity for CO than O2.
However, Hb has a far greater affinity for CO than for O2 so if any CO is in the air the Hb will suck that up instead. But this bond is so strong that the subtle changes in acidity won't release the CO. In effect, that particular Hb molecule can no longer be used to transport oxygen. And that effect lasts until the Hb molecule is regenerated in your body and replaced by a fresh Hb molecule. I think the average lifespan of an Hb molecule is around three-months, so it may that long to recover fully from a serious case of CO poisoning.
This is also the reason that putting someone on 100% oxygen doesn't help all that much in case of CO poisoning. It's not the lack of oxygen that's the problem, it's the lack of oxygen transport capability.
Carbon monoxide - Wikipedia, the free encyclopedia
Hemoglobin - Wikipedia, the free encyclopedia
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just a normal household detector then nothing specific for an aircraft?
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We had the same problem. After a 2 hr leg I always used to get a bit of a rough throat and headache. I mentioned this to one of the other owners and he said he had the same. There was a bit if a smell in the cockpit too, so one day we did a test flight with a CO detector. Lo and behold, 30 minutes into the flight the thing went off....I was going to borrow my plumber friends gas analyser to get a reading but then after some investigation we figured it out.
On our aircraft there is a belly panel which is removed for the annual. It should slot in above the engine cowling but when they had put it back it was not....so there was a small gap. The result was that the exhaust was seeping in between this panel and into the floor space and eventually filling the cockpit with exhaust fumes. Once this was rectified the problem stopped.
On our aircraft there is a belly panel which is removed for the annual. It should slot in above the engine cowling but when they had put it back it was not....so there was a small gap. The result was that the exhaust was seeping in between this panel and into the floor space and eventually filling the cockpit with exhaust fumes. Once this was rectified the problem stopped.
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There was a bit if a smell in the cockpit too
I feel I should point out, though that CO on its own is colourless and odourless, so people shouldn't rely on smell to detect it.
Your story is evidence enough that people need a CO detector in the cockpit.
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just a normal household detector then nothing specific for an aircraft?
I'd say that if it's sensitive enough to detect CO in a household environment, then it would be sensitive enough for the confines of a cockpit. They've always been placed near a vent and somewhere visible too.
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B&Q sell a very much cheaper version as well. Does n't have the 'opened' date bit but otherwise is the same.
For those not aware the leaner you run an enginne the less CO it produces - another benefit?
For those not aware the leaner you run an enginne the less CO it produces - another benefit?
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Trust me, you won't notice those little plastic card things start turning black. They'll sit there for ages and you'll forget all about them. You want something which makes a right racket.
When I had my little encounter, the electronic CO detector went mental at 50ppm. The little chemical plastic square hadn't even registered it.
When I had my little encounter, the electronic CO detector went mental at 50ppm. The little chemical plastic square hadn't even registered it.
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Im going to go and buy one from b and q or somewhere to keep in my flying bag. I think if a serious fault developed you would have more chance with an electronic device.