New process to extend serviceability of hydraulic aircraft components

The Air Force Research Laboratory Materials and Manufacturing Directorate recently completed an extensive effort to help certify a maintenance process that could extend the life of aircraft hydraulic system components.

Through participation in a rapid innovation fund team led by the Air Force Life Cycle Management Center, AFRL researchers successfully helped develop, test and validate the cold spray coating process for the life extension of aircraft hydraulic lines. Cold spray is a technique by which metal particles are accelerated onto a surface through high-pressure application. The force of the impact bonds the metal to the surface without the need for temperatures as high as those typically associated with other deposition processes.

This process was identified as a potential solution for replacement B-1 aircraft hydraulic lines, which are prone to chafing damage.

B-1 hydraulic lines are made of titanium, a strong, lightweight metal that can be bent and routed around tight spaces without collapsing upon itself. These qualities make it ideal for aircraft hydraulic systems. However, titanium does have drawbacks. It is a surface-sensitive material, meaning that any nick or scratch can be detrimental to its overall material properties. Because of the proximity of the B-1 hydraulic lines to landing gear components, chafing is a common occurrence, necessitating frequent inspection and replacement of hydraulic lines. This procedure is a costly and time-consuming endeavor.

To alleviate this problem, the rapid innovation fund team began investigating the use of the cold spray process to apply a protective titanium layer to chafe-prone tubing areas. The thought behind this effort was that the sacrificial titanium layer could endure considerable wear while preventing harm to the material beneath.

Certifying the process for implementation on the aircraft hydraulic tubes was a complex and multi-faceted effort on the part of AFRL researchers and project partners.

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