StacksVerified U.S. regulatory reference

14 CFR §25.939

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (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.
  2. (b)[Reserved]
  3. (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.