What is the meaning of leaks?

Answer 1

This may not be the . I have not heard of a "dynamic leak" exactly.

A hydraulic system such as the hydraulics, or fuel or brake system on an aircraft have components that have moving parts that push the fluid. The system is designed with static seals and dynamic seal.

A static seal is a simple rubber gasket or O-ring that prevents a joing from leaking. The joint may be where two lines are joined together with a B-Nut or where a Line joints to a pump. There are also static seals inside of pumps and actuators where the pieces that are sealed do not move relative to each other.

A dynamic seal is a rubber gasket or O-Ring or T-Seal that holds the pressure of the fluid at a moving surface. The pressure inside an Actuator forces it to move and it has a seal that prevents the pressure from squirting out but allows the rod of the actuator to extend/retract. This is a dynamic seal---one that has to take the forces of the fluid pressure and the friction of the moving surface.

AddendumIn the context of aircraft systems, a dynamic leak would be a leak that occurs only when the system is being operated or is otherwise under pressure. A static leak would be a leak that shows up even when the system is unpressurized. Dynamic leaks are obviously harder to detect as they might only occur during flight when a system (such as flight controls) is being operated.

Good . It would also be hard to detect because a dynamic leak may only occur when an actuator moves to a specific position which cause a leak of a dynamic(moving) seal.