Building my 12iS as an EAB and working on the fuel system. The plans call for fabricating F-12127E as the Main Filter Bypass Fuel Line mounted near the fuel pump. This line has a check valve and bypasses the main fuel filter (10 micron). I am unsure why this is done. I understand that if you had a problem with the "fine filter", this would still allow fuel to "bypass" the filter and make it to the engine and therefore particulate matter greater than 10 microns into the injectors. I don't think this is routinely done on most aircraft fuel systems... Am I missing something? and should I include this on my EAB fuel system? Thanks in advance.