Revision of Hydraulic Systems Airworthiness Standards To Harmonize With European Airworthiness Standards for Transport Category Airplanes

This amendment revises the hydraulic systems design and test requirements of the airworthiness standards for transport category airplanes. The amendment adds appropriate existing Joint Aviation Requirements (JAR) standards to achieve harmonization; moves some of the existing regulatory text to a new advisory circular (AC) 25.1435-1; consolidates and/or separates certain subparagraphs for clarity; and revises airplane static proof pressure test requirements to allow a complete functional (dynamic) airplane test at the hydraulic system relief pressure. These revisions were developed in cooperation with the Joint Aviation Authorities (JAA) of Europe, Transport Canada, and the U.S. and European aviation industry through the Aviation Rulemaking Advisory Committee (ARAC). These changes benefit the public interest by standardizing certain requirements, concepts, and procedures contained in the airworthiness standards without reducing, but potentially enhancing, the current level of safety.