the carbon monoxide indicator thing...

DKirkpatrick

DKirkpatrick

Pre-takeoff checklist
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DKirkpatrick
Hello. Two experienced pilots got very mysteriously killed here in Arkansas about a month ago. Good airplane, two good pilots. I've never used one of those panel mount cards that is supposed to indicate high carbon monoxide.
Question is, are these good, reliable, the best indicator? This problem can sneak up on you, especially in cold weather flying of course.
Would like some best practices type comment.
thanks
dan
 
i also have sensorcon. once a month or so i take to the tail of the truck to ensure its working. its been 2 years, after this winter i will send the unit back to calibrate
 
I have decided if I ever own my own plane again to install an audible carbon monoxide alarm.

I lost a dear friend about 5 1/2 years ago to CO.
 
DavidWhite said:
audible carbon monoxide alarm
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this is audible , but you can get a panel mounted one that is connected to the audio panel as well. the alarm on this one is pretty loud and if you wear a noise cancelling headset, you wont miss it.
 
i'll do my homework. thanks alot
dan
 
From https://www.guardianavionics.com/carbon-monoxide-silent-killer-in-aviation-cockpit-pilot. Of course, they want to sell you electronics, but their detection capabilities eventually expire too. (I've seen from 2-10 years. Here's one that claims 10: Carbon monoxide detector.

Chemical Spot Detectors
We see these in pilot shops and in aircraft all the time – a card placed on the instrument panel with a dot in the center that changes color or turns black in the presence of CO. These are inexpensive and do not require any sort of installation, but don’t make a judgement by the price tag. Though they are better than nothing, most pilots don’t realize that these have a useful life of only 30 to 60 days – so whether you fly the aircraft or not, you have to change these cards 6-12 times a year! Additionally, they are extremely vulnerable to other aromatics in the cabin, so cleaners, solvents, and deodorants may decrease their effectiveness even more.

But even more dangerous, these chemical detectors are incapable of detecting low levels of CO, which when exposed to for longer durations, can cause major symptoms. These chemical spots may begin to subtly change color at 100 PPM, but you may not see a major change until the 200-400 PPM range. By that time, you may be feeling the symptoms of CO poisoning already, so do you think you might be aware enough to detect if that “spot” is darker than before?
We have seen aircraft come into our shop with a spot card on the panel that is 2-3 years old… at that point, it is more of a danger than a solution… one that creates a false sense of security and complacency when it comes to CO risk.​
 
WannFly said:
i also have sensorcon. once a month or so i take to the tail of the truck to ensure its working. its been 2 years, after this winter i will send the unit back to calibrate
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My understanding was that you should never test your sensor directly on the tailpipe of your vehicle as it may well damage it.
 
CaptainXap said:
My understanding was that you should never test your sensor directly on the tailpipe of your vehicle as it may well damage it.
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well its designed to detect CO, so not sure how it will get damaged. i am not shoving it in the pipe, just close enough to get a detection
 
I know a lot of us on the Cessna Pilots Society forums have and like the Sensorcon units, same w/ the BeechTalkers. Most on CPS agree that stick on dot detectors are garbage FWIW.
Sensorcon 20% discount code: Aircraft2021
 
baboss said:
I know a lot of us on the Cessna Pilots Society forums have and like the Sensorcon units, same w/ the BeechTalkers. Most on CPS agree that stick on dot detectors are garbage FWIW.
Sensorcon 20% discount code: Aircraft2021
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+1, have a Sensorcon Inspector
 
The color-changing spot cards are useless for CO monitoring. They are not quantitative, cannot detect low concentrations of CO, and lose function fairly quickly over time without providing obvious warning. They are also difficult to interpret. Is the spot dark enough to worry about yet or not? We did not use these in the chemistry lab for any serious purpose. Home CO detectors are also not useful in an airplane. Their response times are quite long, and will not alarm until there are very high levels of CO present. For aircraft, you need a detector that can detect low concentrations of CO, has a fast response time, and will alarm at lower levels of CO. An affordable option is the Forensic Detectors Vehicle CO monitor. This is one of a class of amperometric CO detection devices that has fairly good specificity for CO, although it can be interfered with by other reducible gases like hydrogen sulfide, but this is not likely to be a factor in an airplane. It will give a digital readout of CO levels, and has a rapid response time and low alarm level. I wouldn't put too much stock in the exactness of the CO ppm values, as they will be less accurate at altitude because of the chemistry used to detect CO. However, for its intended function, alarming the pilot of potentially hazardous CO levels in flight, it will function quite well. I have one of these mounted on my center console, where I can see it and its alarm light and readout. It also has an audible alarm. When my plane was in for annual, it went off in the hangar for sustained low levels of CO coming from the propane heaters there. I occasionally see very low levels of CO during taxi with the canopy open.
 
Sensorcon here too. Spendy, but not dying of asphyxiation seems like a good plan in the Book of Steingar.
 
The Sensorcon is one of several amperometric-type CO detectors. This is the type of device you want in an aircraft, coupled with low or user-adjustable alarm levels. Home detectors don't get excited until you are around 400 ppm :eek: CO.

BTW, amperometric detectors do not have an unlimited lifetime, so they should be replaced at the expiration date listed on the device, which is usually 5 years or so.
 
WannFly said:
well its designed to detect CO, so not sure how it will get damaged. i am not shoving it in the pipe, just close enough to get a detection
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CO sensors get dirty, then will fail to work. That's also why they have a shelf life, they lose their function as the sensor ages and gets contaminated.
 
midwestpa24 said:
CO sensors get dirty, then will fail to work. That's also why they have a shelf life, they lose their function as the sensor ages and gets contaminated.
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ok that makes sense. i do periodically clean the sensor. i need to send it back for calibration after this winter is over
 
+1 SensorCon.

For the OP, I believe there is at least one ADSB-IN gadget with a CO monitor built in as well.
 
I have a Co Guardian. It’s mounted in the panel. It was installed last year right before I bought the plane. Seems to be a pretty good unit. Haven’t had any issues yet.
 
I have read that LOP operation reduces or eliminates the possibility of CO in the exhaust (This is not a joke). It does seem to make sense. Comments, data?
 
WannFly said:
well its designed to detect CO, so not sure how it will get damaged. i am not shoving it in the pipe, just close enough to get a detection
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Water vapor and residual hydrocarbon in exhaust can cook the detector. You can buy CO in a spray can on Amazon... for testing.
 
DoubleD said:
I have read that LOP operation reduces or eliminates the possibility of CO in the exhaust (This is not a joke). It does seem to make sense. Comments, data?
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that is true... if you survive the climb to altitude full rich, you should be OK... if not, well...
 
DoubleD said:
I have read that LOP operation reduces or eliminates the possibility of CO in the exhaust (This is not a joke). It does seem to make sense. Comments, data?
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Common knowledge among those who have spent their career working on emission control.
First graph that pops up from a search...

petrol_engine-emissions.gif



"Peak" is purd near at the "closed-loop mode..." line on the chart. Full rich is somewhere near the "Best Torque" range and, of course, moves to the left of that band as you climb. So, from this chart, full rich gives you 5% or more CO in the exhaust. Lean of peak is less than 1%. The exact numbers won't be right for your IO-360, but the trends will match. The biggest difference will be where the unburned hydrocarbon line starts to rise - that "corner" moves a lot depending on engine / ignition design. The HC and NOx lines will also move up and down quite a bit from engine to engine. CO not quite as much.
 
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I was thinking about a wrist wearable oxymeter instead. I've heard (unconfirmed) that if CO is displacing O2 it will show up on an oxymeter, and one that connected to an iPad (maybe via bluetooth) could possibly sound an alarm. All conjecture for me at this point.
 
I have a sensorcon keep in a little clear pocket next to left window. It’s part of my scan. In fact it helped me realize I had a leaky seal on the baggage compartment in the club 182. Little CO on climbout but did have it building 10-20 ppm level flight more in rear or plane. Replaced seals and closing door correctly dropped me to less than 10ppm.
 
kontiki said:
I was thinking about a wrist wearable oxymeter instead. I've heard (unconfirmed) that if CO is displacing O2 it will show up on an oxymeter, and one that connected to an iPad (maybe via bluetooth) could possibly sound an alarm. All conjecture for me at this point.
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Not necessarily true. The O in the CO is still registers as O2 in most pulse oxmeters, they can't tell the difference. There are some higher end models we use in EMS that can differentiate between CO and O2, but I would guess most consumer grade models can't.
 
Regardless of Sensors the; proper inspection of the system can provide peace of

mind.

In addition to Visual; I use my Leaf Blower.

Simply connect to Exhaust Stack ; turn ON and squirt soapy water.

Bubbles pinpoint defects.

If the Heater Shroud is opened it will assist in hard- to - see areas.

It has identified “scratches” that were really cracks.

Suggest do @ oil change before cold weather.
 
kontiki said:
I've heard (unconfirmed) that if CO is displacing O2 it will show up on an oxymeter, and one that connected to an iPad (maybe via bluetooth) could possibly sound an alarm.
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Not in the way you might think. CO sticks to hemoglobin just like O2 does... in fact, much more tenaciously. The CO turns the hemoglobin red, just like O2 does. The pulse oximeter checks for how red your blood is... and is easily fooled by the CO red. So there's no way to use an oximeter, even with an iPad, to determine if you're oxygenated or poisoned... You could be at the point of death, and the oximeter will show 98% saturated. But saturated with the wrong molecule.
 
I'll take Good Practices for $2000, dead Alex.

"Sensorcon, good annual / condition inspection of the exhaust system."

What is No Brainer?

"And with that, you have now passed Ken Jennings as the most successful Jeopardy Champion!"
 
kontiki said:
I was thinking about a wrist wearable oxymeter instead. I've heard (unconfirmed) that if CO is displacing O2 it will show up on an oxymeter, and one that connected to an iPad (maybe via bluetooth) could possibly sound an alarm. All conjecture for me at this point.
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If I recall from watching this, he said his pulse ox said he was fine.
 
Spend some time going over your exhaust system and plugging any/all openings in the firewall. Get a flashlight and look for telltale soot from any cracks in the tubing, bad slip joints, or failing gaskets; repair or replace as necessary.

Detectors are good, but eliminating the root cause is better.
 
midwestpa24 said:
Not necessarily true. The O in the CO is still registers as O2 in most pulse oxmeters, they can't tell the difference. There are some higher end models we use in EMS that can differentiate between CO and O2, but I would guess most consumer grade models can't.
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Carbonylhemoglobin (hemoglobin bound to CO) has nearly identical spectral properties as oxyhemoglobin, so it is not distinguished by pulse oximetry. (Low concentrations of CO are used to keep your ground beef looking nice and red.) CO poisoning will leave you looking amazingly pink. The way pulse oximeters work is by measuring the ratio of transmitted light 660 and 940 nm which can distinguish between oxy- and deoxy- hemoglobin. The ratio of transmitted light at these two wavelengths can be correlated with oxygenation state. But it cannot distinguish between carbonyl- and oxyhemoglobin. Do use a CO detector in the aircraft for monitoring CO threat levels.
 
erkmann said:
No need to purchase an 'aviation approved' $$$ CO detector. My Sunnec cost $20, has LOUD voice and bright visual alarms w a 30ppm trigger, digital ppm display, 3 AAA batteries with low battery alarm.

https://www.amazon.com/gp/product/B0742FPGCN/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
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What is the response/alarm time of this unit? The most important factor in an aviation-useful CO detector is a rapid response time to alarm-level CO concentrations. Most residential CO detectors have very long alarm/response times for low levels of CO.
 
chemgeek said:
What is the response/alarm time of this unit? The most important factor in an aviation-useful CO detector is a rapid response time to alarm-level CO concentrations. Most residential CO detectors have very long alarm/response times for low levels of CO.
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Chemgeek...so true. After a little testing I see now that my cheapo doesn’t ALARM at 30, it just DISPLAYS it, then goes on to 100 before alarming... sometimes after 90-120 seconds!!! Guess I’m going shopping. Thanks for the heads up.
 
Sensorcon $111 at their website w Discount Code Aircraft2021. Sweeet.
 
SoCal RV Flyer said:
Spend some time going over your exhaust system and plugging any/all openings in the firewall. Get a flashlight and look for telltale soot from any cracks in the tubing, bad slip joints, or failing gaskets; repair or replace as necessary.

Detectors are good, but eliminating the root cause is better.
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A CO detector is a way for you to find out you have a new issue to remedy. And to take immediate action if something has gone wrong.
 
Just got a quick reading CO detector. Started seeing 12-20 ppm CO on it. The alarm goes off at 9ppm. Found that I only get a reading if the lower heat is on, not the defroster. Looking under the cowl, the heat duct from the muffler has a designed in hole in it. That’s probably letting CO from under the cowl into the flow into the cabin floor level duct. This is probably across most Cherokees. 4781E5BE-BFC3-4A16-8638-4B1040019938.jpeg At less that 25-30 ppm you’re not likely to see any noticeable effects, looking at CO absorption. Here’s a chart:
7D0BEA61-4856-4587-A847-A3A1F4678A6C.jpeg
 
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