Cool mornings. Shorter days. Falling leaves. Autumn's arrival does not (generally) prompt the use of a seasonal checklist but changing weather conditions do require a shift in your preflight emphasis.
As outdoor temperatures cool, mice look for a nice, warm nest for winter, and what better place than your airplane? Rodents can damage airplanes in several ways: Their urine is corrosive to aluminum, they chew through wires, and nesting materials can jam cables.
Be extra alert during autumn preflight for the telltale signs of a rodent invasion. Look for damage to seat cushions such as torn fabric—and if you see bits of foam or insulation anywhere in the cabin or cowl, your airplane might have become a mouse condo. It’s gross, but do look for mouse droppings—these can be hard to see on a dark carpet, so use a flashlight to help spot them. And don’t assume hangared airplanes are immune to mice. Those little suckers can get in anywhere.
Meanwhile, you may find the first frost of the season on your wings this time of year, as damp air is attracted to cold metal wings like flies to…uhh…never mind. You get the idea.
Unlike ice, frost does not increase weight significantly—but it greatly increases skin friction drag, reducing a wing’s lift and increasing the stall speed. It’s like covering the aircraft’s wings with sandpaper.
Don’t attempt to remove frost with a broom or a credit card. Odds are you won’t get it all, and it takes very little frost accumulation to have a huge impact on your airplane’s performance. One alternative is to park the aircraft in a hangar to avoid frost contamination. Or you can pick up a spray bottle of TKS deicing fluid to zap the frost, but with the fluid costing almost as much as French perfume, your best option may be to wait a bit.
After sunrise, as the temperature increases, the relative humidity drops, and frost magically sublimates into the atmosphere, clearing you for departure.