carbon monoxide in your Cabin???

[thinwing]

Today we flew to stockton to visit with topgun.My rso had recently purchased a kwj engineering model 300 co detector and we decided to test it on the heater.Stockton is reporting 700 overcast  when we departed Sacramento so I asked for a TEC to Stockton and quickly programed rnav 29r approach into the Garmin 530...right after takeoff,Jana is holding the co detector which starts flashing red and showing 230ppm co.We opened the vents and right after closing cowlflaps/gear doors the co settles down to about 30ppm and stayed there until the approach (gear doors open ,inbound about 90 kts)when it jumped back up to 140 ppm.We landed with out further ado and started monitoring this thing......taxi...down to 30.Topgun guys say...better seal off areas of the cabin where the rudder pedals exit.Ok says I but this a/c just came out of annual.....exaust system is perfect...all slip joints are good and we just finished resealing belly panels.Anybody with a Bravo has noticed a white exaust stain along the left fuselage indicating how closely the exaust stream follows entire fuselage.....so what do you guys think????We have flown this bird close to 200 hrs with no ill effects that I know of.On the drive home Co levels are 5ppm and register 60ppm when detector placed in direct line of exaust pipe from running chev silverado pickup.Are we gassing our selves out???Is 200 ppm something to worry about???...cant wait for your replys....kp couch

[peter]

The highest CO level I see in my airplane is 30 ppm, taxing on the ground with the cabin door open.  Closing the door and flying reduces the level. In cruise the level is generally below 5 ppm.  30 ppm in cruise and 140 ppm on approach are both higher than I would accept. 

[blacknchrome]

That is interesting.  Seems like something's not right.  You're right about the white exhaust on the Bravo - glad I'm not the only one.  Thought it had something to do with the operation - guess it's typical.

 

[thinwing]

Another flight to L A and back this weekend...High Co levels in cabin during takeoff and climb while cowl flaps are full open and mixture full rich during the climb...than after leaning for cruise and closing cowl flaps level disapates to practically zero...I notice a lot rumbling/turbulence by my feet while cowl flaps fully open...is this the cause...and of course of course running full rich is producing a co rich exaust...k

[KLRDMD]

Running LOP will reduce CO levels to essentially zero.

[blacknchrome]

Quote: thinwing

Another flight to L A and back this weekend...High Co levels in cabin during takeoff and climb while cowl flaps are full open and mixture full rich during the climb...than after leaning for cruise and closing cowl flaps level disapates to practically zero...I notice a lot rumbling/turbulence by my feet while cowl flaps fully open...is this the cause...and of course of course running full rich is producing a co rich exaust...k

[thinwing]

Blacknchrome...yes,but since my procedure is to lean to about 1500tit set power for 2400/32in man. and than close cowlflps for cruise,..I dont know for sure which action is reducing the co concentration....reducing power and leaning to more stoichemetric mixture,closing the cowl flaps thus reducing the turbulence arround the footwells or the change in angle of attack by levelling out.The only I am least seeing low levels in cruise...about 8 this time after an hour and a half in cruise...kpc

[sleepingsquirrel]

I was very interested in this topic now that I actually have an aircraft that doesn't take all day to get to service ceiling.  I figured I needed to be educated in use of O2 at least . These numbers in the article are for sea level . I'm going to crawl out on a limb (squirrels are good at that) and say at 18,000 ft the mixture of air is the same percentages as at sea level just about half as much  volume  of each. A little further research and verification might allow us to reasonably reduce the allowable carbon monoxide levels in this article by half if the O2 is cut by half.

Pulse oximetry does not help when hemoglobin is bound to carbon monoxide.  It could be showing proper O2 levels when in fact it ignores hemoglobin  bound to Carbon Monoxide (Carboxyhemoglobin)

  Disclaimer: One often finds that certian relationships may not be linear if one has a government grant with unlimited funding to do the studies. I'm sure that the tables exist somewhere. At what level does carbon monoxide become toxic?
For healthy adults, CO becomes toxic when it reaches a level higher than 50 ppm (parts per million) with continuous exposure over an eight hour period.. When the level of CO becomes higher than that, a person will suffer from symptoms of exposure. Mild exposure over a few hours (a CO level between 70 ppm and 100 ppm) include flu-like symptoms such as headaches, sore eyes and a runny nose. Medium exposure (a CO level between 150 ppm to 300 ppm) will produce dizziness, drowsiness and vomiting. Extreme exposure (a CO level of 400 ppm and higher) will result in unconsciousness, brain damage and death.

[thinwing]

Sleeping squirrel..thankyou for co exposure recomendations...at close as I can figure it,we are being exposed to medium levels...say 200ppm on average upon climb say 20 minutes on average...than up to 3 hours at initially at mild (50/70)tapering to zero while in cruise...than back up to 100 or so shortly after cowl flaps open on ground...none of the symptons mentioned above other than runny nose(hay fever)headache(programing my 5th reroute in 20 minutes from center)Sore eyes (that would be Jana as in sight for....)dizziness/drowiness(Im that way naturally 24/7)and last vomiting episode was at a all night kegger party in college.I think I will start at the rudder pedal panels just aft of the cowl flaps....thanks everybody..kpc

[sleepingsquirrel]

I figured you were OK after 200 hours with no fatalities. My guess is that these are time weighted average numbers as well. 200ppm for eight minutes might give the same effect as 50 to 75ppm for four hours? Everbody is different.

[ELT]

Hi Thinwing,

In the real world, I oversee the operation of EPA mandated ambient air monitoring.  Don't shoot me I fight the new lead rules.  CO is a pollutant we monitor.  Your numbers are many times the backgound and the concentrations on congested highways.  True aircraft do not have emission controlls but your numbers are still high.  CO monitors CAN be inaccurate.  First, check the accuracy of your monitor.  If your monitor is accurate then the problem needs to be found. Sleeping squirrel's data is correct.  We calibrate our equipment with 40ppm tanks and require separate safety monitors.  We do not want our techs exposed to even 40ppm concentrations for long periods of time.

[scottfromiowa]

I agree that even 50ppm is HIGHER than you want to be exposed to for CO.  I am a safety consultant and forklifts in the winter when NOT tuned release CO.  Employees dizzy, headaches and some even nausia/vomiting at levels of 50ppm...working in an enclosed area.  (warehouse for eight hour shift) You do NOT want to mess with CO in the cockpit.  If you identify continue to troubleshoot until you identify and eliminate the problem.

Be safe,

Scott

[kortopates]

Since no one mentions it, Aviation Safety has a good yet very general article on this topic in the current Jan issue. Discusses exposure level affects and looking for sources of exhaust leaks.

One other comment - One of the biggest Myths in Aviation is "it just came out of annual..... therefore my xyz system is perfect". Not only is "airworthy" a far cry from "perfect", but that was yesterday, not today.

Good luck