I'm working on a 1975 Smith Aerostar 601, s/n: 61-0264-102. We have a problem with the fuel level going down in the RH wing tank. Have observed for 2 days with no fuel leak and fuel level hasn't changed. Center fuselage tank is almost full and RH wing tank very low. Question:can the fuel from the RH wing tank bleed back into the center fuselage tank? Does anybody have an inner parts break down of the fuel system, or a fuel system schematic, that they can email or fax me? Any help would be greatly appreciated. You can contact my boss, Mike Lloyd at Tri-City Aviation, ph:423-325-6275. Thank you for your help and support.