Which type of seal is most commonly used to prevent leakage in aircraft hydraulic units?

The O-ring seal is widely used in aircraft hydraulic units primarily due to its efficiency in preventing leakage and its ability to maintain a reliable seal under various operating conditions. O-rings are designed to fit into a groove between two mating surfaces, creating a tight seal that effectively blocks the passage of fluids.

One of the key advantages of O-rings is their versatility; they can be made from different materials, such as nitrile or fluorocarbon, allowing them to be suitable for a range of fluids and temperatures found in hydraulic systems. Furthermore, their simple design means they can be easily installed and replaced, which is crucial in the aircraft industry where maintenance must be performed efficiently.

In hydraulic applications, the pressure exerted by the fluid can help the O-ring to expand slightly, increasing the contact force against the mounting surfaces and thus enhancing the sealing capability. This characteristic makes O-rings particularly effective in high-pressure environments, which are typical in aircraft hydraulic systems.

Other types of seals may have specific applications but do not share the same level of widespread use or effectiveness across all hydraulic applications found in aircraft systems.