Cleaning Your Aircraft

If you’re going to fly airplanes, sooner or later you’re going to need to clean it. Even if you fly from someplace with ramp guys to do this for you, sooner or later you’re going to fly to someplace deserted, and if you don’t know how to do it, it isn’t going to get done and you’re going to fly looking through about a million bugs on the windscreen, often into the sun. If you own your own aircraft, you especially need to learn how to clean your aircraft.

Cleaning the windshield

First thing you need to learn is how to clean the windshield of an aircraft, which is likely Plexiglas. You NEVER want to use anything containing ammonia (common in automotive window cleaners) or anything with alcohol in it (eg automotive windshield wiper fluid) because it will damage it.

What else to use? Well, people love to use strong soaps on airplanes, but you want to avoid any strong, caustic soap on an aircraft because it can corrode the aluminum. You almost certainly don’t need to use soap on your windshield simply to remove the bugs.

Water is actually the solvent for bugs. It dissolves them nicely. In a pinch you can use sopping wet paper towels to clean your windshield, but beware – it will scratch them over time.

There are all sorts of fancy and exotic specialty windshield cleaners and treatments for aircraft, but you don’t need any of them. I don’t like using anything I can’t pick up in any small town.

The best thing to clean your windshield is some liquid/detailer car wax at your local auto parts store, which comes in a squirt bottle. That, and a large, soft fluffy towel, which you can pick up cheaply at Walmart or any decent hotel. Spray the windshield down with the liquid wax, preferably in the shade. Use the towel to gently rub off the dissolved bugs. It will leave a nice film behind which will help you take off the next layer of bugs, next time. Once you get it clean, it’s easy to keep it clean.

Same thing applies to the wing leading edges and struts and nosebowl, which also collect bugs. If the paint is in good shape, and you don’t have a year’s worth of accumulated bugs, you can use the same spray wax on these areas and the same towel. Just be careful to not get the towel oily, wiping down the lower bits.

Cleaning the belly

So now you’ve got the bugs off, but your aircraft has an oily belly from the crankcase breather tossing oil overboard. At this point, people like to reach for a really nasty soap which will corrode the aluminum, but don’t do that.

The best degreaser is mineral spirits, which you can pick up at most auto supply stores. It’s basically varsol that doesn’t stink. Buy a gallon of mineral spirits and a reusable squirt bottle, which some people use to spray water on plants, or at misbehaving cats. Fill the squirt bottle with mineral spirits and you now have the best, safest degreaser there is. Anyone with a radial engine ought to buy a 55 gallon drum of the stuff.

Mineral spirits is a petroleum-based solvent which you shouldn’t breathe, and if you’re going to use it a lot, get a box of latex gloves to avoid getting it on your skin. For Christ’s sake, don’t get it in your eyes.

The good thing about mineral spirits is that it dissolves oil and grease superbly without being corrosive, and it evaporates very slowly, so it does not pose anywhere near the fire risk that gasoline does. Remember, liquid gasoline (and liquid mineral spirits) does not burn – only the evaporated vapour, and only when mixed in the correct ratio with the oxygen in air.

The best way to clean a greasy aircraft belly is to hose it down with the mineral spirits squirt bottle, let it dissolve the oil and grease, then wipe it off. You can use paper towels for this, but I prefer rags. Either way, get rid of the used paper towels/rags after you finish using them for cleaning. They don’t want to risk burning your hangar down, so get them out of your hangar when you are done with them!

The combination of the two above – liquid wax for the bugs up top, and mineral spirits for the oil below – will do a pretty good darned job of cleaning up most airplanes. If you’re preparing an Oshkosh Grand Champion, you may want to get rid of the slight bit of slime that the mineral spirits leaves behind, with another clear squirt bottle of very gentle (eg dish) soap solution that you have mixed up from concentrate and water. Once you wipe off the soap, then you can finish it off with the liquid wax, if you want it ridiculously shiny and clean. Most people don’t bother.

Mineral spirits is also marvellous for degreasing the insides of engine cowls, firewalls, and the engines themselves. It will not hurt anything. Using an old toothbrush to get into the corners with mineral spirits and a rag – this will do wonders at cleaning and degreasing. Doesn’t cost much, and doesn’t take much time, either.

Heavily Oxidized Paint

Many aircraft that spend a lot of time outside don’t look very good, because their paint isn’t shiny any more. If it’s in really rough shape – the paint, usually many decades old, is cracking, peeling and extremely dull – you can’t do anything to fix it, except strip it down to the bare aluminum and apply brand new paint.

However, if the paint isn’t too rough – if it’s just dull – you can probably make it look a LOT better, without spending much money. It will take a little time and effort, though.

If the paint is quite dull, you need to get some “Pre-Wax Cleaner” at the local auto store. I use Mother’s in the red bottle, but the brand is unimportant. Pre-wax cleaner does a marvellous job of cleaning and removing accumulated oxidation from the paint. I don’t recommend that you use any kind of power buffer because unless you are really skilled, you will almost certainly damage the surface with swirls, burns, etc. Leave that to the real professionals. You are going to do it the old-fashioned way – with your triceps. Try not to sweat on the pre-wax cleaner. You probably need the exercise and upper body development anyways.

You apply pre-wax cleaner just like wax – with one rag to put it one, and another to take it off, I might suggest separate sets of rags for each colour, to avoid smearing them. Do the dark colours first, then the light colours.

Once you get the paint shiny, then get a new set of rags and apply “cleaner wax” which will help clean up the surface a tiny bit, but more importantly it will leave a coat of wax on the surface to help protect it against the UV in the sunlight.

Scratched Windshields

If your Plexiglas is a mess, and liquid wax doesn’t fix it, you can do better.

If the windshield is heavily crazed with internal flaws from decades of UV, there isn’t much you can do.

But if you just have some surface scratches, you can really improve them. Again, I don’t use any exotic stuff. I just “scratch remover” from the auto parts store which is really marvellous stuff – a very fine rubbing compound. You can use it on paint, and on Plexiglas to remove light surface scratches. After you’ve done what you can to repair it with scratch remover, you can use cleaner car wax and liquid squirter wax on the Plexiglas to keep it clean. Be sure to clean both the inside as well as the outside of the windshield with liquid wax!

Rubber Bits

For the rubber stuff on an aircraft, I like to just use old-fashioned Armor All from the auto parts store, and a rag. It will clean the rubber and leave it nice and shiny.

Bottom Line

It doesn’t cost a lot of money to keep your aircraft clean and shiny – just some reasonably-priced supplies from any auto parts store, and some effort on your part.

Keeping an aircraft clean is more than just some OCD fetish. You can see better out of a clean windshield, and a clean propeller and wing develop more thrust and lift. And if you keep your aircraft clean, you can see trouble developing early on and fix it before it becomes a big problem. A good example of this is metal cracking – if you catch it early on before it spreads, you can often stop drill it. But you can’t fix what you can’t see!

Cleaning an aircraft is an essential part of its annual inspection. If you do it, you save money because your mechanic doesn’t have to.

So, you really don’t have any excuse to not clean your aircraft, and plenty of reasons to do it!

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acboyd@gmail.com Sept 2011