Page 10 - Oct22T

An Ounce of Prevention by Elliott Cox
Walk around nearly any airplane, and you’ll see a few spots of corrosion here and there if you look closely enough. If you’re willing to spend a little bit of time and money on corrosion prevention, you’ll
Osave loads of time and money on corrosion repair.
ne of the most significant factors in the corro- and 90 days in a mild environment. Frequent inspections, sion equation is the environment where your emphasizing a few corrosion-prone areas, will go a long airplane lives. An airplane tied down on an open way toward keeping your airplane squeaky clean.
ramp in Baton Rouge, Louisiana, will develop
corrosion much faster than an airplane stored in a hangar in St. George, Utah. Unfortunately, a hangar isn’t always an option, but even if your airplane spends the majority of its life tied down on the ramp, there are some things you can do to minimize the potential for corrosion.
AC 43-4B (available as a free PDF download from the FAA’s website) recommends that a “crew familiar with cor- rosion problems and treatment” perform corrosion checks every 15 days for an aircraft operating in a severe envi- ronment (see map), 45 days in a moderate environment,
The entire underside of an airplane takes a real beating and should be cleaned on a regular basis. Exhaust, oils, fuel, and whatever was scattered, spilled or spewed onto the runways and taxiways is thrown at a high velocity in the direction of the belly, and much of it stays there. Engine exhaust, whether it’s from a turbine or recipro- cating engine, quite literally creates corrosion hot spots. Because hot air holds more moisture than cold air, exhaust gas provides a steady stream of moist, hot air combined with all the contaminants of the outgas and byproducts of combustion directly onto everything behind it.
All of that nasty stuff streaks down the belly and sticks to the paint, supplying an adhesive coating that keeps cor- rosive elements lovingly sandwiched between a layer of scum and your aluminum. Thankfully, all it takes to get rid of all that crud is a little bit of quality time wiping the belly down with a good aluminum-safe degreaser from your favorite aviation supply store. Keeping a good qual- ity paint job clean and dry is the next best thing you can do for your airplane to storing it in a climate-controlled hangar. If moisture and air can’t get to bare metal, there’s no chance of corrosion.
The only part of an airplane that takes a bigger beat- ing than the belly is the landing gear, especially if it’s retractable. The gear is exposed to the same abuse as the belly, but there are more cracks, crevices, moving parts, hydraulic fluid, and grease that make the undercarriage more difficult to keep clean and protected from corro- sion. It takes more time to clean the gear than it does the belly, but time spent degreasing, cleaning and thoroughly re-greasing all those moving parts will help ensure that you’ll have three reliable legs under you every time you move the gear lever.
Some other areas that deserve a good look are under and around batteries and lavatories. Batteries are literally
8 • TWIN & TURBINE / October 2022