Aircraft Cleaning

  • E-Mail this Article
  • View Printable Article
  • Text size:

    • A
    • A
    • A

Remember the good-old days when the choices of products to clean your airplane were few? Today it seems we are overwhelmed with choices to the point of bewilderment, but AVweb has some suggestions to keep a healthy shine on your steed.

Maintenance

It used to be that a bucket of soap -- any soap -- and a rag was all you needed to clean anything. That same bucket of soap, it turns out, could be the worst thing you can use on your airplane (or your modern auto for that matter).

Why are airplanes so different? There are two factors to consider: the paint and the aluminum underneath.

Modern Paint

Paint has become more and more trouble-free (although application is still a big environmental problem). People do not want to be waxing airplanes, and they don't have to if they treat the paint properly.

Flitz Metal Polish

If you want to polish unpainted aluminum then you definitely are buying into a long-term commitment of constant care. In this case, gentle, aircraft-qualified polish is definitely called for -- not automotive stuff that could well have micro-abrasives as part of the formulation. Aircraft Spruce & Specialty offers Easy Aluminum polish as one dedicated choice. Flitz metal polish is another choice with a good reputation. Flitz also makes a fiberglass restorer and liquid wax products -- all available from Aircraft Spruce.

Today's paint is far more chemically complex and durable, but has to be treated right or it will dull and fail early -- even polyurethane. Additionally, because certain sections of the aircraft are subject to much worse dirt and oils than others, there is good reason to restrict certain heavy-duty cleaners to areas such as the belly where the paint is subject to exhaust residue and oil.

Aluminum

Paint is one reason why specialty cleaners have been developed. The second reason is that aluminum -- both the sheet metal and the castings for things such as the landing gear -- is very chemically sensitive to many common cleaning agents.

Aluminum has the wonderful properties of strength and light weight, but there is an Achilles heel of sorts. Certain chemicals found in many common cleaners have alkaline properties that can have an adverse effect on both paint and the aluminum itself. These chemicals can contribute to hydrogen embrittlement or structural weakening of highly stressed aluminum, or in the case of sheet metal, a dulling of unpainted surfaces, which promotes pitting and corrosion.

The concern is great enough that the FAA has issued an advisory circular warning of care in using common alkaline cleaning agents. The surprising thing is that some of these "harsh" chemicals have been commonly used in the past. They have undoubtedly contributed to the early dulling and destruction of aircraft paint when used by well-meaning but uninformed people.

Cleaners such as Formula 409 and regular Simple Green have no place in an aircraft cleaning kit. Note that there is now a special Simple Green designed to meet the safety standards set forth for aircraft. The container clearly indicates its different formulation. It is called Extreme Simple Green and has been completely reformulated to be safe on aircraft when properly used. It's also biodegradable.

Debugging

Mirror Glaze Plastic Cleaner and Polish

Getting bug stains off of wings is always a chore, but there are new cleaners that work on dissolving the proteins in the bugs rather than abrasive action typical of the old ways to get the wings clean. Clean wings can be good for a few knots.

Another area of concern is with Plexiglas in aircraft, which can be dulled, scratched and crazed by common household chemical use, especially with dirty rags used in cleaning the general surfaces of the aircraft. Plexiglas needs TLC and separate handling and chemicals when it comes to cleaning.

Anything other than new, cotton flannel is asking for trouble, whether during the cleaning cycle or at any time the windshield is cleaned during a fuel-up. There is no room for paper towels of any sort when it comes to cleaning Plexiglas, either. Always decline the line service offer to do the windshield if you want max. life for your windows.

Plexiglas must be cleaned in stages, with plenty of water to keep any dirt flowing off the surfaces. This is then followed by the clean (no shop rags) flannel cloth with an approved Plexiglas cleaner or polish designed expressly for the job.

My favorite brand has always been Meguiar's Mirror Glaze. Use Plastic Cleaner Number 17 for cleaning and getting rid of hairline scratches. Follow with a coat of Meguiar's Number 10 Plastic Polish.

Avoid Power Washers

Probably one of the easiest ways to clean and possibly ruin the paint or even the structure of an airplane is to use a power washer loaded up with a harsh, powerful, alkaline cleaner. These washers develop over 1000 psi of water pressure and can warp skins, peel paint, and even drive alkaline chemicals under the skin through seams -- particularly if the washer is directed from the back to the front of the aircraft and into the seams. These chemicals then sit in the seams or other areas where they can literally fester, causing corrosion.

The worst thing that you can do is to blast water up into the plane from angles never designed to protect the structure from the elements in the normal course of flying.

Use the Proper Cleaners

Extreme Simple Green for Aircraft

Catalog sources such as Aircraft Spruce have a substantial choice of cleaning agents dedicated to aircraft structures. And while they may cost a little more than an auto-store source, the long-term health of the airplane is what's at stake.

The investment does not have to be that great. A general-purpose mild cleaner is needed to clean the "sunny side" of the plane. Hand washing the aircraft skin has the benefit of enabling you to go over the entire skin, looking for any early signs of problems such as corrosion or missing paint. And regardless of the wash agent you use, there is no substitute for through and complete rinsing with the universal solvent -- water.

Never go over the Plexiglas with washrags. When you are washing the plane use your bare hands to caress the plastic clean. Once all the cleaning is done and the windows are dry, then it's time for the Plexiglas cleaner and polish.

A Dirty Belly

A belly stained with grease, oil and exhaust is par for the course, especially in older planes with tired engines. There are dedicated products for this purpose that do a good job, while leaving your paint intact. Of course, the longer you wait to attack the problem the worse it will be, so let's get to it.

If the grime is really thick your best bet is a pressure sprayer, but not the 1000-psi variety. Something as simple as a garden sprayer will work to dispense the cleaner. Shop air and a wand with a tube dipped into cleaner will also do the job. In this case the cleaner must be liquid rather than a gel cleaner. Even the new Extreme Simple Green claims to be able to do this tough job when diluted as recommended and used in a pressure sprayer.

Give it a chance to work before washing it off. This is one chore where repeating the cycle will be necessary, as will elbow grease to get the grime off. And don't forget the eye protection while you are under the aircraft.

If you want to do a really thorough job, a creeper to slide under the aircraft will be very helpful. And if the job is monumental from years of accumulation, you may want to consider an inexpensive, disposable, plastic tarp to catch the bulk of the grease to be environmentally responsible.

Most airports have designated wash areas so that the run-off will not go into the normal drainage system. All the concentrated chemicals are simply too harsh to dump into normal drains. Be sure to use these designated wash areas whenever they are available.

Suggested Cleaners

Aircraft Spruce has a large selection of cleaners and polishes to choose from. The first one that you will want to use is a gentle wash product approved for aviation. One example is Safety Wash, which meets Boeing standards. For heavy grease and oil you can try a more powerful degreaser that has a gel consistency for tough belly stains. One recommended product is Hydrasolve.

For general-purpose and spot cleaning, Extreme Simple Green will also do the trick. Follow the directions on the container for dilution.

The real secret to making the process less painful is to not wait too long between cleanings. You will find that it is well worthwhile in the long-term health of the aircraft.

Polishing

Racers Edge

If you feel that you must polish the aircraft, as we said, use an aircraft-qualified polish that does not contain any abrasives. A good choice here is Racer's Edge polish, which meets Boeing safety standards.

If the paint is faded, then you will have to get rid of oxidation with a polishing compound. There are several grades of polishing compounds with varying degrees of cutting action.


In the horizontal mode (such as on top of the wing), the weight of the orbital buffer alone is sufficient; otherwise use your body to apply modest pressure to the buffing process. Always keep the buffer moving.

This is an area where you should seek the counsel of a knowledgeable aircraft-paint care person, because it's easy to ruin paint if you get too aggressive or use the wrong polishing technique. Usually, more than one grade of compound is required, and you will best be served by staying with a polishing system such as from 3M.

Rotary electric buffers that spin under 1800 rpm or have variable speeds are the realm of the pro or knowledgeable amateur. You can burn through the paint in a heartbeat. With combination orbital buffers you have much less chance of doing harm.

The big issue is trying to go too fast and trying to use too aggressive cleaners to speed up the process. Some faded paint just cannot be saved no matter what you do because the oxidation just runs too deep. You need to know when to call it quits.



For more about maintaining general aviation aircraft, check out AVweb's Maintenance section.