FUEL SYSTEMS

General: The following fuel capacity is provided:

In flight, fuel from auxiliary systems should be transferred to main system as soon as possible to improve loading conditions and reduce fire hazards.

Main Fuel System: Comprises:

1. Twelve self-sealing fuel cells in the wing center section. There are four sets of three cells each. In normal operation each engine is served by one set.

2. Four electrically-driven booster pumps with strainers (one for each set of cells). They are in the bomb bay just under the cells.

3. Four triple-port shut-off valves.

On each valve: One port leads to an engine; one port leads to a set of cells; and one port interconnects to the other three valves. The "cross-over" connection allows fuel from any set of cells to serve any engine in an emergency, and permits equalizing flow between systems. These valves are under the front spar in the bomb bay.

4. Four engine-driven pumps with strainers are located—one in each nacelle.

5. Four electrically controlled primers are located—one on each carburetor.

6. Two venting systems. One serves the six cells (two sets of three each), one fuel gauge, and the two carburetor vapor chambers on the right side of airplane centerline; the other serves similarly on the left. Two outside openings, one of scoop, near the junction of the fuselage and wing, and the other an outlet aft of the scoop serve each vent system. The scoop opening serves two purposes: it rams air into cells to keep pressure slightly above atmospheric; its relief valve allows pressure to escape when airplane is at rest and when the cell pressure reaches 0.3 p.s.i. (0.2 Kg./sq.cm.). The second valve is solely a relief valve, with a flush outlet.

SPECIAL NOTE: a. Should both valves fail, atmospheric venting (but not ramming) may be obtained by disconnecting the vent lines at the vent valves and allowing cells to vent inside fuselage.

7. On future airplanes and, as soon as possible, on present airplanes, newly designed outlets will be installed which will replace the Kenyon valves.

93. Fuel Transfer Pump Panel    94. Life Raft Cradles

7. One electrically driven transfer pump allows transfer of fuel from one set of cells through the transfer panel.

8. Wing drain and booster pump vent lines empty overboard under bulkhead at Station 5.0. Provides drainage for booster pumps and for wing cell compartments. The two shut-off valves are normally open but must be closed during combat.

9. Main fuel system supply lines and cell interconnecting, or manifold lines are self-sealing.

Auxiliary Wing Tank Fuel System: Comprises:

1. Six self-sealing fuel cells. Three in each wing, outboard of the wheel well.

2. One 2-way selector shut-off valve which may be connected to the main transfer pump. This allows auxiliary wing tank fuel from either set of 3 cells to be transferred into any one of the four sets of cells in the main system.

3. Two venting systems, one for each set of three cells, right and left. The characteristics are similar to the main venting systems, except that each vent has only one opening.

4. Auxiliary wing cell fuel supply lines are self-sealing.

Fuel System Indicators:

Pressure—Gauges measuring fuel pressure at the carburetors are mounted on the Co-Pilot's Instrument Panel. (See photo Page 2.)

93. Fuel Transfer Pump Panel    129. Fuel Gauge Drain Valves

Quantity-Sight gauges, mounted on the forward face of bulkhead at Station 4.0 show the quantity of fuel in each unit of the system. In case of damage to the gauge vent or supply lines, shut-off valves are provided on top of the gauges and at the supply take-off under the center section, to prevent the loss of fluid. (See Pages 51 and 52.)

No fuel quantity gauges are provided in either auxiliary system. A glass tube between the wing cell selector valve and the transfer pump shows flow of gasoline being transferred.

NOTE: Inclinometer on inboard side of water jug must read zero when gauge readings are taken.

81. Ammeters , 82. Voltmeter Selector Switch, 83. Generator Switches,
84. Vacuum Selector Valve, 85. Voltmeter, 86. Fuel Gauges

Bomb Bay Tanks

Bomb Bay Tanks are provided for auxiliary installation. These tanks are equipped with a single two-way valve which will take suction from either or both tanks. The outlet leads to a C-10 pump which will transfer the fuel either to a "T" on the main valve cross-connection or to the fuel transfer panel for distribution to the main tanks. Both installations are used.

September 24 2012

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