A new Research Bulletin describing the evolution of the fuel system aboard NR16020is now up on the TIGHAR website. Click on the link here
-----------------
These are my two posts of today and yesterday on the "Mystery rods" thread that describe the use of the fuel system.
Contrary to modern twin engined planes the Electra had a fuel system that fed both engines from the same tank. The right valve under the throttles is a standard Electra valve, with "right engine on," "left engine on," "both engines on ," and "both engines off" positions choosing which engine is to receive fuel from the fuel system. The left valve is in series with the right valve and is also almost standard, it selects the fuel tank to use, "right 97 gal. wing tank," "left 97 gal wing tank," "right 102 gal wing tank," "left 102 gal wing fuel tank," "off," and then the added position of "fuselage tanks." When in the "fuselage tanks" position it then opens the port to a third valve that selects which of the fuselage tanks to use. If it was desired to use fuel from one of the two forward 118 gallon tanks then the third valve was turned to "off" and fourth valve was opened to chose "right" or "left."
The above description is quite straight forward and should not confuse anybody.
Now looking at the rest of the fuel plumbing diagram in the Electra we come to the confusing part. There are two additional valves, the first labeled "stripping valve" and the one just below it on the diagram labeled "...RD," the rest of the label that is cut off is "forward floor valve." This valve duplicates the left valve on the instrument panel (this is the upper left valve on the diagram that is cut off) and both of these valves are connected in parallel allowing selecting any of the fuel tanks. This second valve is used to transfer fuel INTO a selected fuel tank. The valve on the instrument panel selects the tank that fuel is drawn OUT OF to go to the engines. The forward floor valve is connected to the stripping valve and the stripping valve selects where the fuel to be transferred comes from, either from the wobble pump or from the tank selected for supplying fuel to the engine.
Two examples will make this clear. Let's say all the fuel from the number 5 fuselage tank has been used up. Earhart then switches the left fuel selector valve away from the "fuselage" position to one of the wing tank positions to keep the engines running. She then sets the stripping valve to the wobble pump position and sets the forward floor valve to one of the wing tanks positions and then pumps the handle to move the remaining fuel from the depleted fuselage tank into the selected wing tank. After this is completed she then sets both of these valves back to off. (Note, only fuel from the fuselage tanks can be moved with the wobble pump and it can only be sent to a wing tank. Also, the plane must be using a wing tank during this operation, not one of the fuselage tanks. )
gl