What the [Beep] is that Beep?

Well, that was interesting.

My Condition Inspection is due. The A&P knows I have a professional-type Carbon Monoxide detector, and always asks me to take a flight and log the levels before the inspection.

Popped the detector in my shirt pocket, climbed aboard, and put on my headset. I had switched back to a standard headset, and decided to do a test transmission before starting the engine.

Odd. When I hit the Push to Talk switch, I heard three beeps: beep beep beep.

Huh. Fiddle awhile, then try with the microphone plug disconnected. Beep beep beep.

Fiddled more. Then unplugged the earphone plug as well, and hit the PTT. Beep beep beep.

What the hey?

Where is the sound even COMING from. The radio speaker itself? Shouldn't, with the headphone adaptor plugged into it, even with no headset attached.

Other than the warning buzzer for my ejection seat (which sounds quite different) there were NO other devices with speaker or beepers installed.

Got out of the plane, switched headsets, and the beeping was gone. But...shoot, it was beeping WITHOUT a headset installed.

Took the flight. Turned the detector back on (it had auto-shutoff).... CO at the panel level was a max of 15 PPM during climb, cabin heater on or off. About 6 PPM at cruise, and during glide. Maximum was a momentary 22 PPM during full-power climb, measured underneath the panel between my calves. All well within margins.

Didn't hear any beeping. I tucked the meter back in my shirt and flew home. Land, park in front of the hangar and shut the engine down.

When I heard a beep. It was the CO detector doing an auto shutoff.

Then it hit. I pulled out the detector, turned it back on, and watched its display as I hit the PTT switch. Reading jumped to ~300 PPM...and the three-beep high-CO warning sounded.

The CO detector apparently has some sensitive circuitry; stray RF from the mighty Icom was messing with it. It had stopped when I'd switched headsets because it did its auto-shutdown while I was changing over, and I didn't turn it on again until I was flying.

Geeze, that was weird.

Oh, and yes, I'll be replacing the compass correction card as part of the inspection....
Attachment 8456

Ron Wanttaja

While you're at it, you might want to add an anti-rotation "tic" mark to your ASI glass. Any time the limit marks are installed on the glass, a "tic" mark that goes from the instrument glass across the bezel is required to determine if the glass has rotated, thereby moving the limit mark.

Carbon monoxide hazard in an open cockpit?

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Originally Posted by melann

While you're at it, you might want to add an anti-rotation "tic" mark to your ASI glass. Any time the limit marks are installed on the glass, a "tic" mark that goes from the instrument glass across the bezel is required to determine if the glass has rotated, thereby moving the limit mark.

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Thanks, Mel, I'll try pick that up this week.

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Originally Posted by Frank Giger

Carbon monoxide hazard in an open cockpit?

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Oh, hay-el yes. The cockpit is a low-pressure area, so exhaust fumes will tend to collect there. Think of the fuselage as a wing, with a flat bottom and an arched top (where the cabin sticks up).

Maybe not so prevalent in a WWI replica with the typical tiny windscreens they have. But here's a stab at the wind flow around a Fly Baby cockpit. The little curlicue is where the low pressure is.
http://www.bowersflybaby.com/stories/slipstream.JPG

The guy who checked me out in the Fly Baby actually got CO poisoning in a Starduster while flying to Oshkosh. He managed to land and climb out, then went to sleep under the wing.

I got hit by it as a passenger in a Mooney once, and am determined to avoid a rematch.

Ron Wanttaja

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Originally Posted by rwanttaja

Thanks, Mel, I'll try pick that up this week.

Ron Wanttaja

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The simplest way is to just extend the radial red line across the bezel.

Last time I was replacing smoke detector batteries I kept hearing a low battery chirp after I'd done them all. I couldn't localize which one was causing a problem and then I realized it was my silly parrot emulating the noise. She's a card that way, she also makes the squeaky noise my shoes make on the kitchen floor. I don't notice it until I stop walking and the squeaks continue. She also makes airplane noises. She's particularly enamored with my neighbors Seabee. She'll make the engine sound even if it is parked shutoff in front of our house and she sees it.

Yep, the one time we get CO in the Navion cockpit is with the canopy open and slower flight. When the canopy is closed the airflow comes from the tailcone and out around the canopy rails (low pressure area). With the canopy open, you're scooping the stuff swirling around the wing. It's the same reason that Navions tend to find corrosion in the left wing root sometimes.

How do you like that Pyle, Ron? Wasn't familiar with them so after seeing your pic I checked Amazon. Hmmm... mixed reviews. Price seems right. Would you be OK with one in a closed cockpit?

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Originally Posted by CarlOrton

How do you like that Pyle, Ron? Wasn't familiar with them so after seeing your pic I checked Amazon. Hmmm... mixed reviews. Price seems right. Would you be OK with one in a closed cockpit?

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Biggest drawback I see is that it's life-limited. The sensor is good for only five years.

I had trouble getting mine to work on Sunday. Kept reading zero, even when I held it in my car exhaust.

Then...for some reason....it started working. In its defense, it HAD been off for months. Possibly had to do some sort of internal reset (and yes, I did replace the battery).

Biggest drawback is that it's really awkward to hang in the cockpit. No clips or anything on it.

This is my second one (I bought it when my original one no longer worked, and I found out about the five-year-life limit. But I wanted a readout, not just a warning tone, and one consumer CO detector I bought HAD a readout, but (after buying it) found it had a minimum reading of 30 PPM (e.g., read zero unless level exceeded 30 PPM).

I'd be OK with it in a closed cockpit, and have lent it to some of my EAA chapter mates. Best indication I got once was when I was taxying on a windy day and the wind pushed a bit of exhaust smell into the cockpit. Meter immediately registered it, about 80 PPM, then dropped back to ~6 or so.

Maybe it was higher than 80 PPM, but at least it recognized the spike.

Price is pretty good ($90 via Walmart), but, again, you'll need to buy a new one every few years.

Ron Wanttaja

Your Fun Meter seems to be pegged even during a condition inspection.

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Originally Posted by DBurr

Your Fun Meter seems to be pegged even during a condition inspection.

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It's not pegged; it's at the top of the yellow arc. Enough fun to be cautious about, but not necessarily dangerous. :-)

Ron Wanttaja

Thanks, Ron. While I’m not thrilled about the sensor life, from what I understand just about all of ‘em have a limit. I’ll consider it further as I get nearer to first flight.