The last part of tank installation is the fuel filter, but this is not open to debate. Reality trumps anyone's opinion; use a good filter or have problems. It is that simple. Competition fliers have proven this many times throughout many years. I relearn this lesson every 200 or so flights on my competition aircraft.
    Despite triple-filtering the fuel during refueling, from a 100-mesh screen down to a 250-mesh screen, I must clean the onboard fuel filters in my competition aircraft every 200 flights or they start to clog. Alcohol-insoluble material builds up inside the filters and must be removed using paint thinner. If the filters didn't catch this material, it would eventually clog small carburetor sections or fuel-pump parts. Nothing but grief comes of this.
    It is also a good idea to install a second filter in the muffler pressure line, between the muffler and the fuel tank. This limits the amount of junk the engine blows back into the fuel tank.
    The only caveat about using filters is to make sure their sections are tight to prevent air leaks. Clean the filters every 200-300 flights for non-pumped engines or every 200 flights for pump-equipped engines.   

Click on photo to view large image with caption

The onboard fuel tank is perfectly sized, constructed, plumbed, and positioned; now we can go flying—except the fuel tank is still empty. We can't do more than test-glide the airplane without fuel, so how do we get it into the aircraft's tank?
    For several years, my early refueling system was a 2-ounce turkey baster with a fuel tube attached. It was slow, but it worked! Such systems are still available, but in larger sizes, as shown. These squeeze bulbs are convenient backups if the primary refueling system fails at the field. You may want to include one in your field box just in case.
    But more sophisticated refueling methods are the most popular by far. As shown, there are four popular types. There are various kinds of hand pumps, some of which fit on the plastic fuel jug and use a hand-crank pump. Rotate the handle one direction and the fuel flows into the aircraft. Rotate the other way and out it comes after the flying day is done.
    Some, such as the Du-Bro system shown, also hold the glow-plug igniter and spare parts. Others, such as Dave Brown Products' Pump-N-Go system, may include the fuel container as well.
    There are refueling systems that attach directly to the fuel container and resemble the hand systems but use electric pumps. They usually also contain batteries for power. Field-box fuel pumps may also contain their own batteries, but most use the 12-volt field-box battery. Some systems, such as the yellow Sullivan fuel pump in the picture, have their own on-off/directional switches, and others use the fuel-pump switch on the field box's power panel (more about that next month), as the Mark X electric fuel pump does.
    The fuel line used to plumb the refueling system is usually the same reinforced silicone line used onboard the aircraft. Many electric-fuel-pump manufacturers recommend that the large fuel line be used to reduce wear on the pump. Sometimes that requires using a short length of medium fuel line over the filling nozzle and then applying the large line over the assembly.
    The refueling system has fuel filters; be sure to clean them more often than you clean the onboard filters. Refueling filters may be used for more than one aircraft, so they require more frequent service.

Now that the aircraft is fueled and ready to go, we need to turn it over and light the glow plug to get it started. We also need to hold it in place safely during run-up and settings.
    Next month, which will be the last installment of the engine segment, I will cover field boxes, batteries, starters, glow-plug igniters, and chicken sticks.  MA