
HOMEBUILTS
Homebuilders can improve the fuel system of an airplane under construction
in a number of ways to reduce the likelihood of vapor lock. NASA vents incorporated
into the vent system help provide positive pressure. Fuel pumps should be
installed in the fuel tanks, or as close to the fuel tank as possible, and
should be of the maximum pressure and flow rating allowable for the carb.
Any 90° fittings should be replaced with 45° fittings, or tubing
with very smooth gradual bends. Fittings should be made as tight as possible
to prevent air from entering the line. Lines should be secured to prevent
vibration & harmonics. Fuel lines in the engine compartment should be
insulated to prevent heat from soaking through to the fuel. Fuel lines should
not be located in close proximity to hot spots in the engine compartment.
Composite materials used for the construction of some homebuilts may react
negatively when they come in contact with fuel. The early Vari-eze homebuilts
had a tendance for the spar to come apart after fuel tank leaks dribbled
fuel onto the spar. Homebuilders should contact the kit manufacturer to
see if material used throughout the airplane is compatible with the type
of fuel you will be using and to receive other recommendations.