Volume: 1Date: 2024-01-01Original Date: 2024-01-01Title: Section 27.939 - Turbine engine operating characteristics.Context:
Title 14 - Aeronautics and Space. CHAPTER I - FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION. SUBCHAPTER C - AIRCRAFT. PART 27 - AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT. Subpart E - Powerplant. - Rotor Drive System.
§ 27.939Turbine engine operating characteristics.(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 rotorcraft and of the engine.(b) The turbine engine air inlet system may not, as a result of airflow distortion during normal operation, cause vibration harmful to the engine.
(c) For governor-controlled engines, it must be shown that there exists no hazardous torsional instability of the
drive system associated with critical combinations of power, rotational speed, and control displacement.
Code of Federal Regulations /
Title 14 - Aeronautics and Space /
Vol. 1 / 2024-01-01532
[Amdt. 27-1, 32 FR 6914, May 5, 1967, as amended by Amdt. 27-11, 41 FR 55469, Dec. 20, 1976]