Cold Temperature Hydraulic Seals for Aerospace Hydraulic Systems

ABSTRACT: Aircraft hydraulic systems have traditionally been required to operate down to -65F. However, with the advancement of unmanned air vehicles (UAVs), operating envelopes at high altitudes are evolving. UAVs are loitering at high altitudes for upwards of 24 hours. As a result, sections of the hydraulic system are becoming cold soaked and prone to leakage. As a consequence, the DoD is seeking new hydraulic sealing capability to reduce or eliminate leakage experienced while operating in cold soaked environments. The new seals should support UAV hydraulic system operations for components capable of operating up to 5000 psi, in MIL-PRF-83282, MIL-PRF-87257, MIL-PRF-5606 hydraulic oil and Nitrogen gas. The seals should be capable of sealing in storage down to -100F and operation from -70F to 160F (threshold) and 275F (objective). METSS proposes to meet the SBIR program requirements using o-ring configurations based on a core-shell design. The core-shell design provides greater flexibility to design a composite product that will meet the stated physical, chemical, and thermal response requirements. Polymer-polymer core-shell designs will considered, as well as designs incorporating an inner core made of a mechanical actuator (spring or otherwise) encapsulated with a outer shell to support system interfacing and surface mating requirements. BENEFIT: The technology developed under this SBIR program should be highly adaptable to other high performance DoD and industrial hydraulic fluid applications. Other candidate military platforms include NASA high altitude research vehicles and surveillance platforms for homeland security. Commercial applications include sealing on platforms used for high altitude weather surveillance, and monitoring of hurricanes and forest fires.