If the airport has only 100LL available, it is permissible, absent any limitations of the engine manufacturer, to mix 100LL and 89 octane gasoline, for use in two-stroke engines. A 50-50 ratio will boost the octane rating and limit the amount of lead available for fouling. Generally speaking, this is a reasonable compromise when 89 octane is not available.

Two-stroke engine manufacturers, and four-storke engines used on powered parachutes, typically recommend the use of 89 octane minimum auto fuel for their engines. Additives are put into auto gas primarily to reduce harmful emissions rather than boost performance. The additives are supposed to be listed at the pump, but the accuracy of this posting should be questioned.

Methanol alcohol has corrosive properties and can damage engines. Engine manufacturers do not recommend more that 3 percent methanol in fuel. Consult the POH for specifics on your engine.

Ethanol alcohol is less corrosive than methanol. However, it attracts water and is not as economical as gasoline.Ethanol does not get very good fuel economy. Avoid fuels with any more than 10 percent of ethanol in it. Consult your POH for specifics on your engine.

Manufacturers provide specific recommendations for the percentage of alcohol in fuel. The posting on the pump may not be accurate and alcohol content can vary greatly between fuel brands and stations. Additionally, higher percentages of alcohol will be added to auto gas in the future. A simple test can be conducted to measure the fuel’s alcohol content to ensure the fuel you use stays within the manufacturer’s recommendations.

Use a general aviation sump collector, which includes graduation marks. Add water to a specific mark. Then add fuel to fill the collector up to the line for gas. Cover the top and shake it vigorously. After it settles, the water and alcohol will combine and it will look like there is now more water in the sump collector. The difference between the initial amount of water you first put into the collector and the new level of combined water and alcohol equals the amount of alcohol in the fuel. Compare this amount of alcohol and the amount of fuel to determine the percentage of alcohol content in the fuel.

Methyl Tertiary Butyl Ether (MTBE) does not have the corrosive or water attractive properties of the previously mentioned additives and is added to fuel to improve air quality. It has been banned in several states because it is carcinogenic and has been found in groundwater. It does not attract water, but it is expensive, so you will find it only in some of the better grade fuels.

Clean fuel is imperative for the safe operation of a PPC. Of the accidents attributed to powerplant failure from fuel contamination, most have been traced to:

Rust is common in metal fuel containers and is a common fuel contaminant. Metal fuel tanks should be filled after each flight, or at least after the last flight of the day to prevent moisture condensation within the tank. Another way to prevent fuel contamination is to avoid refueling from cans and drums. Use a water filtering funnel or a funnel with a chamois skin when refueling from cans or drums. However, the use of a chamois will not always ensure decontaminated fuel. Worn-out chamois will not filter water; neither will a new, clean chamois that is already water-wet or damp. Most imitation chamois skins will not filter water.

Letting fuel sit for weeks without using it will cause it to go bad. Even if gas does not go bad, it will often lose its octane with time. For those that premix gasoline and two-stroke oil, there is another set of problems. Fuel and oil are normally mixed at a 50:1 ratio. If premixed gas sits in a plastic container for a while, the gas will evaporate out leaving a richer oil mixture in the container. In any case, fresh gas should be used as much as possible.

Never mix oil and fuel in an enclosed area. Not only are the fumes irritating, but with the right fuel-air mixture you can cause an explosion. Do all oil and gas mixing outside. Refueling from fuel cans should also be done outside. Never smoke while refueling.

Be careful refueling an aircraft that has just landed. There is the danger of spilling fuel on a hot engine component, particularly an exhaust system component.

Refueling should be done using only safety-approved fuel containers. The fuel containers should be marked with the type of fuel stored in them. Confusing premixed fuel and fuel that has no oil in it can be disastrous.

There are advantages to both metal and plastic containers. Metal cans won’t allow the sun’s ultraviolet rays in to harm the fuel. It also won’t develop static charges like a plastic container may. However, a metal can will be more prone to sweating when going from cool to warm temperatures on humid days. Metal cans and metal gas tanks are best kept either empty, or full of fuel to leave no room for moist air.

Plastic fuel containers are easy to handle, inexpensive, available at discount stores, and do not scratch the finish on airframes. Plastic cans also do not sweat, so they don’t need to be stored topped off. However, fuel does deteriorate a little faster in plastic. Also, plastic containers can get charged with static electricity while sliding around in the bed of a pickup truck, especially if the truck has a plastic bed liner. Many states now have laws prohibiting people from filling plastic containers unless first placed on the ground.

Static electricity can also be formed by the friction of air passing over the surfaces of a powered parachute in flight and by the flow of fuel through the hose and nozzle during refueling, if fueling at a pump. Nylon, Dacron, and wool clothing are especially prone to accumulate and discharge static electricity from the person to the funnel or nozzle. To guard against the possibility of static electricity igniting fuel fumes, a ground wire should be attached to the aircraft before the fuel cap is removed from the tank. The refueling nozzle should then be grounded to the aircraft before refueling is begun, and should remain grounded throughout the refueling process.