Normal Use

(I)

Warm up taken off and fly for the first fifteen minutes on reserve tanks. This is to provide space in the reserve tanks for the vapour return from the carburetors. Switch both engines to the left dropable tank until almost dry then shift to right dropable tank until almost dry. Determine hourly fuel consumption from the charts in Appendix II. Fuel gauges are not installed in the dropable tanks. Do not drop external tanks unless for increase range or for combat. Use up the fuel in the outer wing tanks (if inst) then use main tanks, and switch back to RESERVE for the remainder of the flight.

WARNING:

Always check the fuel level in the tank before trying to operate the engine from that tank. To check the level in the outer tank, press the low level test switch on the side of the warning light box. It is not possible to check the fuel level in the dropable tanks.

(2)

On modified airplanes the booster pumps should be operated during take-off) and landing to prevent engine failure which may result from engine-driven fuel pump failure. The booster pumps should also be operated during flight whenever necessary to maintain the required 16 to 18 lb/sq. in. fuel pressure. On modified airplanes the booster pump master switches should be on at all times. The speed control switch should be in the EMERGENCY position during take-off and landing to prevent engine failure which may result from engine-driven fuel pump failure. The booster pumps should also be operated on EMERGENCY whenever necessary during flight to maintain the desired fuel pressure of 16 to 18 lb/sq. in. The speed control switches have no effect on the dropable tank booster pumps. On modified airplanes the booster pump switches merely supply power to the booster pumps. The proper pump is turned on by contacts on the tank selector valve.

NOTE: Never exceed 250 mph indicated with 300 gallon dropable tanks installed.

(3)

To release drop tanks:

(a) Raise flaps and landing year.

(b) Turn tank selector valves to MAIN, RESERVE or OUTER WING.

(c) Move the arming switch to ARM or SAFE.

(d) Turn the selector switches ON for tank(s) to be dropped.

(e) Press the release button when flying at an angle not greater than 30.degrees from the horizontal.

(f) Full fuel tanks may be dropped without danger at airspeeds up to 400 mph. Empty 150 gallon tanks should be dropped only while flying at an airspeed of 160 mph or less. On late airplanes, dropable tanks are equipped with displacement struts which increase the safe dropping speed to 350 mph.

WARNING:

EMPTY 300 GALLON TANKS ARE TO BE DROPPED ONLY IN AN EMERGENCY as the tanks may hit the airplane when released. To drop the tanks, it is necessary to slow the airplane down to 120 mph with landing gear and flaps up to avoid serious damage.