Low-Cost DIY Hangar Projects: Aircraft Cabin Dehumidifier

Like so many others, we hangar the bird and treat the airplane’s wings, fuselage, and tail feathers to an internal spray corrosion treatment regimen every couple of years. I make sure to fly the airplane no less than once a week, and each time, get the engine up to operating temperature and keep it there for at least 45 minutes.

However, I wondered how I might protect our precious radio stack from the ravages of moisture and salt. 

I have had issues before with humidity and other kinds of electronic gadgets. Over the years, I found that when we left our musical instrument amplifiers idle in a humid environment, the rheostats would corrode at their contact points, resulting in a loud crackling noise when the volume was turned up or down. Thankfully, a little contact cleaner sprayed into the works, and a vigorous rotation of the volume knob usually cleared up the situation. And come to think of it, I had the same experience with the intercom volume and squelch controls on our Cessna.  

Our instrument panel contains the full spectrum of avionics history, from that 30-year-old intercom system and three light marker beacons,  to a couple of venerable King KX 155 NavComs, and more recently a digital transponder, IFR GPS, and autopilot. I noticed that each time I opened the boxes containing these new digital toys, the first thing that fell out was a little pack of silica gel commonly referred to as a desiccant. When these valuable little devices are being shipped, the manufacturers take the time to protect them from excess moisture. At this point my trusty co-owner, co-pilot, and spouse, observed that they made this kind of humidity absorbing desiccant for closets, footlockers, and even entire rooms. A trip to the hardware store was in order!

Full disclosure, what follows is not backed up by any scientific studies, rather is a product of backyard engineering and a little experience. 

Purchase number one consisted of a “closet hanging moisture absorber” designed to hang in your closet next to your clothes and catch the absorbed water. The top of the bag contains the water absorbent material, and the bottom section is a clear plastic bag to catch the water. These come in a variety of sizes and are manufactured by several companies. 

As it turned out, the plastic hook at the top of the dehumidifier was a perfect fit for the polished Cessna control yoke shaft. These come in packages of from three to eight, and usually last a couple weeks during the high humidity season. 

Purchase number two consisted of a bright red plastic bucket. Reading the instructions on the dehumidifier carton, we learned that the water catch bag would not leak, and no other precautions would be required. Having always thought that Murphy’s Law was incredibly optimistic, the $5 bucket seemed a good purchase. The rest was easy. Hang the bag on the passenger side control yoke shaft, place the bucket squarely below the bag on the floor, close the doors and let the magic happen. 

Well, not so fast.

Unless I wanted to dehumidify all of Northeast Florida, it made sense to check the door seals for a good fit, close the fresh air vents, and make sure the cabin was relatively sealed off from the elements.

The unscientific results are in. I have not had a repeat of the intercom system corrosion issues, the bag and bucket are easy to remove and replace before and after each flight, and the bag fills up on schedule as promised. Oh, and the inside of the Cardinal is much drier, and smells even better.

The cost of this unscientific dehumidifier: about $5 a bag plus the bucket. Peace of mind: priceless!