To wash an airplane there are many items you will need to keep in mind. The first is safety while working on the tarmac of an airfield. When moving any vehicle on the tarmac the driver should always maneuver the vehicle in square turns. The reason for this is so that the pilots of the other airplanes can predict the movement of your vehicle. A person should never drive their car or truck under the wing of larger planes. This can be dangerous because the top of the vehicle can catch a part of the plane and cause damage or if the plane is starting up. If a pilot does not see the vehicle when starting up his plane some loose part from the vehicle could come off and hit the prop or be sucked into the jet engine and besides it's just not safe.
Planes are designed with very light-weight material so that more free weight can be carried by the plane's structure. Thus, parts of a plane are easy to dent and or tear. Planes are not cheap and the parts that make them up are expensive to repair or replace if damaged, not to mention that the damage could cause problems to the plane that would make it unsafe to fly. Just remember it this way, a plane costs twice as much as a boat and a boat cost twice as much as a car. Using safety on a taxiway is very important. It's just plane smart and it shows proper etiquette to the other pilots around you.
When moving a plane into an area, if need be, to be able to wash it, there are a few parts of the plane you can use to move it by. When holding the prop you should always hold it near the center or where the spinner is. This will prevent you from possibly bending the prop, which can happen if you tried to hold it on the outer part of the prop. Another way to safely move a plane, if you absolutely have to, is to use the tow bar that is attached to the lower bracket of the front wheel. If you have to turn the plane then grab the leading edge of the wing next to the fuselage. This is where the wing is strongest.
When you are washing a plane there are some key points to remember so as not to damage any instruments or windows. The windows of a plane are made of Plexiglas. Plexiglas can be scratched very easily. To wash the windscreen and windows you need to use light up and down motions so as to cause minimal scratches. There is no way to not scratch a Plexiglas window. That is why a product called Mirror Glaze will be used after washing to remove a lot of the scratches. Do not push on the front windshield when washing. If you break a windshield on a small Cessna single prop it can cost and upward of $1000 dollars. The reason for this is that a front windshield is bolted in by rivets that are flush and it a very pain staking job to get the rivets out and put new ones in to make them all flush.
Near the rear of the plane is a hole that sticks out just about an eighth of an inch that is called the static board. When washing near these instruments never spray directly into the hole. Spray around it and when using a wash mitt wash around it not over it. Under the wing of most planes is a Pitot tube that is used for wind speed. It is an L-shaped looking tube. Water should never be sprayed directly into the hole, just as with the static board. If you have to step on a plane to get to where you can reach the higher parts so you can wash them, always make sure you are standing on a part of the plane that is designated as an area to walk on. Most planes have these areas marked. If you are using a pressure washer, then use the sprayer in such a way that you hold the trigger in one hand and hold the hose out at arm's length with the other hand so that the hose does not bang on any part of the plane. If you feel you are falling never grab onto any part of the plane to try and save yourself. A small antenna will not save you from falling and if you pull it off it will be expensive to replace. When you fall push away from the plane and fall flat so as to break your fall.
When you wash a plane make sure all leading edges (the areas of the plane that come in first contact with the air) are washed with a bug pad. Planes may be going twice as fast as cars but they do get bugs on them. When you are spraying or washing a part of the plane always be aware of areas where paint is flaking or chipping. Keep in mind that the wings have moving parts. This is important because, if you can, you want the ability to be able to move these two parts so that all the dirt and grease can be removed. When you wash ailerons, elevators, flaps, and rudder areas you can't use that much pressure to wash them or you might cause a dent in the wing. If you need to use a little more pressure then usual you should put your arm under it so as to give the area more support and aid in not running the possibility of bending or putting a dent in it.
To spray the plane, front to back motions should be made as if the plane was moving in a forward motion. The reason for this is some holes on the plane are designed so that water can pass over them in this manner but not allow any water to get in them. Most of the grease on the plane will be on the under belly of the plane. You may want to buy a creeper with metal wheels to be able to get under the plane and effectively remove the grease. For bigger planes you want to have at least a 6-8 foot ladder on hand to be able to get the top of the rear wings and the fuselage. The easiest method to get the grease off is by using a citrus degreaser. It is perfectly biodegradable but some places are still strict on the use of it. So if you can, just spray it on but if worse comes to worse you will have to spray it on a rag, wipe it on, then wipe it off. More often then not you can just spray it on and pressure wash it off.
Always keep the trigger at least two and a half feet away. This is a safe distance so that the dirt and soap will come off but at the same time the spray will not damage the plane. In order for you to dry the plane after it has been washed you should use a big towel. You can buy one at almost any store for a good price. These towels will just be for planes only. The bigger the towel the faster you can dry a plane not to mention the easier it will be. Use wide wiping motions to cover the whole plane. If a towel should ever hit the ground be sure you shake the towel so that any rocks from the ground are not in the towel and you will not scratch any part of the plane. To dry the windows you want to wipe very lightly or even dab them as if you were using a sponge to dry them. This will help reduce the scratches you put into the window.
Now if you still have energy it is time to wax!