Gear Q

[franknes]

What exactly is the shuttle valve on the Seminole used for, is it emergency extension?

 

[RiddlePilot]

Man, I should SO know this.

 

[jdflight]

If I knew what a "shuttle valve" is, I could answer this.

 

[A300Capt]

Shuttle valves are used in various systems to provide alternate means of power. They are used in pneumatic and hydraulic systems depending on what you're talking about. Think of them as "flapper" valves. When primary power (pressure) is removed, the "shuttle" or "flapper" valve moves either through hydraulic or pneumatic means to allow alternate pressure to automatically power the system. Many times this action is invisible to the pilot.

 

[jdflight]

Okay. In looking at my Seminole schematics, no, the shuttle valve is not used for emergency extension. It is used to reverse the flow of the hydraulic pressure in normal gear operation.