Smart investment

As the owner of a small aircraft myself, I understand the concerns about the cost of mandated equipment, especially for something as unsatisfying as a CO detector. Pilots would much rather spend money on new avionics, lighting, performance enhancements, or new paint jobs. It’s like buying tires: necessary for safety, but not very exciting.

Why is this important? There’s an iceberg hidden in the reported statistics. From 1982 until 2020, 31 crashes resulting in 42 fatalities and four serious injuries were attributed to carbon monoxide poisoning. That isn’t a huge number but to those who lost a family member, it was life-altering. The FAA’s Service Difficulty Report (SDR) database added another 45 incidents involving a defect, leak, or failure in engine exhaust systems from 1993 to 2020. OK, another relatively small number reported by mechanics that an exhaust system had failed.

Unfortunately, not enough mechanics take the time to file a report—they just fix it. As a result, I’m certain that there are many more “almosts” where significant amounts of CO entered the cabin and the pilot was significantly compromised but was able to land safely. There is no requirement under Part 91 to submit a report, so why invite trouble? But that’s not always smart in aviation.

Most annuals do not include the FAA-recommended exhaust pressure test; you have to ask. The test is far more reliable in detecting pinhole leaks and very small cracks than a visual check, which attempts to eyeball what cannot be seen without significant disassembly.

CO is a potential problem, and let’s face it, our exhaust systems are built light, they’re generally inaccessible for a thorough visual inspection. The designs haven’t improved significantly in 40 years or longer. Much of the fleet is also getting a bit long-in-the-tooth (old), so the parts and pieces must be constantly checked and replaced.

Panel-attached passive spot CO detectors have two significant limitations: They are only effective for 90 days and the pilot has to be diligent enough to notice the small dot changing color when significantly CO-dosed. That’s betting on long odds, but the devices are cheap.

Having seen all this from the inside, when I purchased my 34-year-old aircraft, I visited the aviation aisle at the local home improvement store for an active CO detector for about $30. These devices typically alert at about 50 parts per million (ppm) depending on where they are placed in the cabin. Over a long flight, even below that alert level, let’s just say the ol’ brain will be somewhat fogged, but you may not be aware. That’s an excuse for a flubbed landing but it’s not a good long-term strategy, especially when the outcome could be a lot worse.

After considerable discussion with the NTSB specialists and taking into account the iceberg aspect of the data, the board decided to give the FAA the option of approving something that did not require a technical standard order (TSO) approval and installation by an A&P. Greater flexibility greatly reduced the price of safety. Whether the FAA decides to follow our recommendation remains to be seen.

After learning much more about carbon monoxide, I purchased another, better, commercially available unit (about $200) that is one-third the size of the home model and begins to alert at 10 ppm. Not only that, but it gives a readout of the ppm level. Nice! It then goes silent and advises you on every 10 ppm increase until it gets to about 50 ppm where it really begins to fuss. I placed it near the front seat heater duct and attached it with “aviation-approved” Velcro, easily moved if needed.

Based on a dozen flights to date, a 10- to 15-ppm alert typically occurs while taxiing and occasionally during runup. In climb, it sometimes goes to about 20 ppm and in cruise drops to zero. Using the heater does not cause any changes, which means the shroud around the muffler is still solid. But if anything changes for the worse, I’ll know it long before my in-flight decision making or my landings, if you pardon the term, are impacted.

Regardless of whether FAA gets around to requiring a reasonably priced CO monitor, which we hope it will, this is a smart investment for any piston aircraft operator or a renter who is flying the high-mileage fleet. It isn’t as much fun as a barrel of monkeys, but it will take a significant headache or much worse out of your flight operations.