The International Cessna^® 170 Association

As winter is rapidly approaching, many of us are reaching over and pulling the CABIN HEATER Knob. (No I don't mean the co-pilots finger, Wingnut!) How long as it been since you used your heater? When was your muffler last pressure checked? Was it really done at the last annual? Do you have a Carbon Monoxide Detector in your plane? How old is it? Do you know the signs and symptoms of Carbon Monoxide Poisoning? If you aren't sure of the answer to any of these questions it might be time to do a little further research. I'll even help with the last one; Headache, Nausea, Vomiting, Dizziness, Fatigue, may be experienced as a result of Richard's Christmas Party or CO!

In 2005 we lost a C-170 in the Portland, OR area due to this exact problem. Lets make sure man and machine are both ready for a safe winter of flying.

Link to NTSB Report
http://www.ntsb.gov/_layouts/ntsb.aviat ... 090&akey=1




Jon "Jughead" Counsell
Safety Officer

I have pulled the knob twice now. Even though I watched them visually check the mufflers at the annual it was not pressure checked. I was checking the CO detecter frequently and paying close attention to signs and symptoms.

Funny thing is, way back when I was renting I never gave it much thought. Now that I am an owner, it has been foremost in my mind.

There are some quality battery powered CO detectors on the market that alert and display the PPM.
It would be a sound investment and velcro it between the seats on the floor.

CO disperses incredibly even thru a volume of air so you can put the detector most anywhere and still be reliable.
The one I have alerts at 15PPM which triggers on long taxies and climb outs.

If you wait until you're showing symptoms, it's probably too late.

I dislike pulling the exhaust apart every year but since its an AD to check the heat muff, I do it. The cracks I've found are often adjacent to the welds and can be hard to see, so I like the idea of the soap check but honestly I just look very closely at every weld. The good thing about doing this check frequently; the parts are covered in anti-seize and seldom does the hardware break. When I look at a plane, I look at the state of the hardware to see whether this check has really been accomplished.

I have previously asked about a source for the leadlike material that is supposed to surround where the exhaust pipes enter the heater muff. I am curious if there would be any issue with forming an aluminum "washer" type item to surround the rear exhaust pipe where it goes into the muff. This would be where the leadlike material is supposed to go?

170C wrote:I have previously asked about a source for the leadlike material that is supposed to surround where the exhaust pipes enter the heater muff. I am curious if there would be any issue with forming an aluminum "washer" type item to surround the rear exhaust pipe where it goes into the muff. This would be where the leadlike material is supposed to go?

Frank, those seals do look very much like lead, but I believe they are aluminum. I've seen them in a catalog, but for the life of me I can't remember where.

AWI and Acorn Welding list them on their website. We talked about these seals here.

I haven't pushed the heater knob in for a few months it seems. I never thought the heater did much, but on Sunday, I went to close the defrost vent to re-direct air and burned my finger! I've been getting concerned about co lately and not trusting the co card. I ordered the sensorcon detector. It's American, affordable and looks super tough in the video.
http://sensorcon.com/products/portable- ... fgodLG8OhQ

The seals mentioned by Frank do not seal against CO. They improve the efficiency of the heater muff by reducing the loss of heated air being supplied. There is no harm in their being absent otherwise.