{"data":{"id":"us/14-cfr-31.33","jurisdiction":"us","citation":"14 CFR 31.33","heading":"Materials.","body":"(a) The suitability and durability of all materials must be established on the basis of experience or tests. Materials must conform to approved specifications that will ensure that they have the strength and other properties assumed in the design data.\n(b) Material strength properties must be based on enough tests of material conforming to specifications so as to establish design values on a statistical basis.","path":["Title 14—Aeronautics and Space","CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION","SUBCHAPTER C—AIRCRAFT","PART 31—AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS","Subpart D—Design Construction"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-14.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:24:20Z","sha256":"ef17e79b067624cfe8bf829d5c9de17640d25bb5e32338a8b6600ae20cd49f93","source_id":"us-cfr","stale":true,"prev":"us/14-cfr-31.31","next":"us/14-cfr-31.35"},"notice":"GroundRules: Original legal text. Not legal advice."}