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AIRPLANE MANUAL - DC-3

XV. HYDRAULIC SYSTEM, LANDING GEAR AND FLAP OPERATION

A. Control Mechanism

1. Valve Levers

There are four valve controls which control landing gear and flap operation:

(a) Engine Selector Valve Lever

Each engine drives a high pressure oil pump which is connected to the four-way engine selector valve. The valve is mounted just below the fluid tank sight gauge and carries connections to the hydraulic system and to the Sperry Pilot. When the lever is straight up and down the left engine pumps to the hydraulic system and the right engine supplies the Sperry Pilot. Rotating the selector valve 60 degrees forward connects the left engine to the Sperry Pilot and the right engine to the hydraulic system.

(b) Shut-Off Valve Control

At about the middle of the hydraulic control panel there is a star type control which operates the shut-off valve. Normally this control is wired in the "OFF" position, during which time the landing gear, flaps and brakes may be operated with hand pump pressure if necessary. If it is desired to pump up the pressure tank with the hand pump, the shut-off valve control must be turned to "ON". When pumping up the pressure tank with the hand pump, the rear pressure gauge (see B-3, page 76) will register hand pump pressure. When the shut-off valve is in the "OFF" position, the gauge will not register hand pump pressure.

Below the shut-off valve control is the wing flap valve lever, mounted so that

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