Metal Versus Plastic Fuel Containers  Mixing Two-Stroke Oil and Fuel Starting System There are advantages to using both metal and plastic  containers. Metal cans will not allow the sun’s ultraviolet  rays in to harm the fuel. It also will not develop static charges  that a plastic container develops. However, a metal can is  more prone to sweating when going from cool to warm  temperatures on humid days. Metal cans and 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 fi nish on  airframes. Plastic cans also do not sweat, and do not 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.  [Figure 4-19] The passage of fuel through a chamois increases the charge  of static electricity and the danger of sparks. The aircraft must be properly grounded and the nozzle,  chamois filter, and funnel bonded to the aircraft. If a can is  used, it should be connected to either the grounding post or  the funnel. Cell phones should not be used while refueling  due to possible fi re risks. Two-stroke engines require special two-stroke oil to be mixed  into the fuel before entering the engine to provide lubrication.  In some engines, an oil injection pump is used to deliver the  exact amount of oil into the intake of the engine depending  on the throttle setting. An advantage of an oil injection  system is that pilots do not need to premix any oil into the  fuel. However, an important preflight check is to ensure the  two-stroke oil reservoir is properly fi lled. If a two-stroke engine does not have an oil injection system,  it is critical to mix the oil with the fuel before it is put into  the tank. Just pouring oil into the fuel tank does not allow  the oil to mix with the gas, and makes it difficult to measure  the proper amount of oil for mixing.  To mix two-stroke oil: Many states now have laws prohibiting people from fi lling  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 WSC aircraft 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.  Most small aircraft use a direct-cranking electric starter  system. This system consists of a source of electricity, wiring,  switches, and solenoids to operate the starter and a starter  motor. The starter engages the aircraft flywheel or gearbox,  rotating the engine at a speed that allows the engine to start  and maintain operation. Electrical power for starting is usually supplied by an on-board  battery. When the battery switch is turned ON, electricity is  • Find a clean, approved container. Pour some gas into  it to help pre-dilute the two-stroke oil. • Pour in a known amount of two-stroke oil into the  container. Oil should be approved for air-cooled  engines at 50:1 mixing ratio (check the engine  manufacturer for proper fuel to oil ratio for the WSC  aircraft). Use a measuring cup if necessary. Shake the  oil-gas mixture to dilute the oil with gasoline. • Add gasoline until the 50:1 ratio is reached. If using a  water separating funnel, ensure the funnel is grounded  or at least in contact with the fuel container. • Put the cap on the fuel can and shake the gasoline and  oil mixture thoroughly. Figure 4-19. With these translucent containers, it can be noted that  the left hand container is just auto fuel and the right hand container  shows the auto fuel is premixed with oil for a two-stroke engine. 4-16