{"data":{"id":"us/14-cfr-25.939","jurisdiction":"us","citation":"14 CFR 25.939","heading":"Turbine engine operating characteristics.","body":"(a) Turbine engine operating characteristics must be investigated in flight to determine that no adverse characteristics (such as stall, surge, or flameout) are present, to a hazardous degree, during normal and emergency operation within the range of operating limitations of the airplane and of the engine.\n(b) [Reserved]\n(c) The turbine engine air inlet system may not, as a result of air flow distortion during normal operation, cause vibration harmful to the engine.","path":["Title 14—Aeronautics and Space","CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION","SUBCHAPTER C—AIRCRAFT","PART 25—AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES","Subpart E—Powerplant"],"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":"87f7cbc02da9d7a52f432f8596069b559bbaa5b9962342414caf7c5773023bf7","source_id":"us-cfr","stale":true,"prev":"us/14-cfr-25.937","next":"us/14-cfr-25.941"},"notice":"GroundRules: Original legal text. Not legal advice."}