50-37-01 LUSCOMBE: Applies to All Model 8C Airplanes With a Continental A-75 Carburetor Engine Installed But Not Equipped With Either Wing Fuel Tanks, or an Engine- Driven Fuel Pump and the Chevrolet AC-R1 Hand Pump.
To be accomplished prior to the next annual inspection, but in no case later than October 1, 1951.
It has come to our attention that some Luscombe 8C airplanes equipped with carburetor engines and fuselage fuel tanks are in service without appropriate modifications to the fuel system. Because of the marginal rate of fuel flow which can exist with the gravity feed fuselage fuel tank, engine failure may occur during takeoff and climb under low fuel conditions. To eliminate this hazard, the airplane should be modified to provide either an engine-driven fuel pump and a hand operated Chevrolet AC-R1 wobble pump, or two 11.5-gallon wing fuel tanks and revised fuel system replacing the 14-gallon fuselage tank system.
Another satisfactory installation is to provide one 11.5-gallon wing fuel tank. This tank must not feed through the fuselage tank but must feed the engine directly. A placard must also be placed on the instrument panel or at the fuel valve reading, "For takeoff and landing, use 11.5- gallon wing tank only".
(Luscombe Service Letter, dated August 4, 1947, titled "Method of Effecting Engine Change for Increased Horsepower" pertains to this same subject.)