A hydraulic power supply system operates the landing gears, brakes, cowl flaps, wing flaps, blower clutches and the windshield wipers. Hydraulic fluid is supplied by gravity from the hydraulic fluid reservoir to the engine-driven hydraulic pumps (one on each engine) which supply fluid pressure for the hydraulic systems and the autopilot system. The autopilot pressure regulator automatically reduces the pressure, supplied by the engine-driven pump, to the amount required for operation of the autopilot and returns the fluid to the reservoir when the autopilot is not operating. The fluis flow from either engine-driven pump may be selected by means of the hydraulic pump selector valve, located on the hydraulic control panel.
Hydraulic pump selector valve lever:
The hydraulic pump selector valve lever provides selection of two modes of operation: TAKE-OFF POSITION and GYRO PILOT POSITION. In the TAKE-OFF POSITION, both the left and right engine pumps supply pressure for the hydraulic systems. In the GYRO PILOT POSITION, the left engine pump supplies pressure for the autopilot system and the right engine pump supplies pressure for the hydraulic system.
Note: In the current version of the VSKYLABS C-47 the hydraulic pump selector valve lever is inoperative, and the selected mode is the TAKE-OFF POSITION by default.
Hydraulic hand pump:
The hydraulic hand pump, located at the bottom of the hydraulic control panel, has a handle that extends between the pilot's and co-pilot's seats. This hand-pump is used when the engine-driven hydraulic pumps fail to supply sufficient pressure, when the hydraulic fluid supply (except the hand pump reserve) has been lost, or for ground operation of the hydraulic system when engines are not running. The hand pump may be used to supply pressure to any unit operated by the hydraulic system, except the autopilot.
Hand pump to pressure accumulator shutoff valve handle (star valve):
The hand pump to pressure accumulator shutoff valve handle is located on the hydraulic control panel. It has two placarded positions, ON and OFF.
Note: The hydraulic hand pump in the current version of the VSKYLABS C-47 is not installed nor operational.
