Which option best describes the alternate static valve operation?

Which option best describes the alternate static valve operation?

• A. External to Internal Cabin Pressure
• B. Internal to External Pressure
• C. External to External Pressure
• D. Internal to Internal Pressure

Answer: (D)

Alternate static valve operation is about providing a backup pressure source for the cabin/air data system without pulling air from or venting air to the outside. In this helicopter, the valve switches the static pressure source entirely within the aircraft’s own pressurization plumbing—an internal-to-internal path. That means the system uses another internal point for static pressure rather than using the external ambient port or venting to the exterior. The result is that the static pressure sensed by the cabin controllers and instruments stays within the aircraft’s internal network, maintaining operation when the primary external static source is unavailable. This is why it’s described as Internal to Internal Pressure.

Alternate static valve operation is about providing a backup pressure source for the cabin/air data system without pulling air from or venting air to the outside. In this helicopter, the valve switches the static pressure source entirely within the aircraft’s own pressurization plumbing—an internal-to-internal path. That means the system uses another internal point for static pressure rather than using the external ambient port or venting to the exterior. The result is that the static pressure sensed by the cabin controllers and instruments stays within the aircraft’s internal network, maintaining operation when the primary external static source is unavailable. This is why it’s described as Internal to Internal Pressure.